5-Fluorouracil for glaucoma surgery(review)

Transcription

1 Cochrane Database of Systematic Reviews 5-Fluorouracil for glaucoma surgery(review) GreenE,WilkinsM,BunceC,WormaldR GreenE,WilkinsM,BunceC,WormaldR. 5-Fluorouracil for glaucoma surgery. Cochrane Database of Systematic Reviews 2014, Issue 2. Art. No.: CD DOI: / CD pub Fluorouracil for glaucoma surgery(review) Copyright 2014 The Cochrane Collaboration. Published by John Wiley& Sons, Ltd.

2 T A B L E O F C O N T E N T S HEADER ABSTRACT PLAIN LANGUAGE SUMMARY SUMMARY OF FINDINGS FOR THE MAIN COMPARISON BACKGROUND OBJECTIVES METHODS RESULTS Figure Figure Figure Figure ADDITIONAL SUMMARY OF FINDINGS DISCUSSION AUTHORS CONCLUSIONS ACKNOWLEDGEMENTS REFERENCES CHARACTERISTICS OF STUDIES DATA AND ANALYSES Analysis 1.1. Comparison 1 Regular-dose postoperative 5-Fluorouracil (5-FU) versus control, Outcome 1 Failure at 12 months Analysis 1.2. Comparison 1 Regular-dose postoperative 5-Fluorouracil (5-FU) versus control, Outcome 2 Mean intraocular pressure at 12 months Analysis 2.1. Comparison 2 Regular dose intraoperative 5-Fluorouracil (5-FU) versus placebo or control, primary trabeculectomy, Outcome 1 Failure at 12 months Analysis 2.2. Comparison 2 Regular dose intraoperative 5-Fluorouracil (5-FU) versus placebo or control, primary trabeculectomy, Outcome 2 Mean intraocular pressure (IOP) at 12 months Analysis 3.1. Comparison 3 Comparison of subgroups: intraoperative versus postoperative 5-Fluorouracil (5-FU) in primary trabeculectomy, Outcome 1 Failure at 12 months Analysis 3.2. Comparison 3 Comparison of subgroups: intraoperative versus postoperative 5-Fluorouracil (5-FU) in primary trabeculectomy, Outcome 2 Intraocular pressure at 12 months ADDITIONAL TABLES APPENDICES WHAT S NEW HISTORY CONTRIBUTIONS OF AUTHORS DECLARATIONS OF INTEREST SOURCES OF SUPPORT DIFFERENCES BETWEEN PROTOCOL AND REVIEW INDEX TERMS i

3 [Intervention Review] 5-Fluorouracil for glaucoma surgery Elspeth Green 1, Mark Wilkins 2, Catey Bunce 3, Richard Wormald 3,4 1 Norfolk and Norwich University Hospital, Norwich, UK. 2 Moorfields Eye Hospital NHS Foundation Trust, London, UK. 3 Research and Development Department, Moorfields Eye Hospital NHS Foundation Trust, London, UK. 4 Cochrane Eyes and Vision Group, ICEH, London School of Hygiene & Tropical Medicine, London, UK Contact address: Richard Wormald, Cochrane Eyes and Vision Group, ICEH, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. r.wormald@ucl.ac.uk. Editorial group: Cochrane Eyes and Vision Group. Publication status and date: New search for studies and content updated (conclusions changed), published in Issue 2, Citation: Green E, Wilkins M, Bunce C, Wormald R. 5-Fluorouracil for glaucoma surgery. Cochrane Database of Systematic Reviews 2014, Issue 2. Art. No.: CD DOI: / CD pub2. Background A B S T R A C T Trabeculectomy is performed as a treatment for many types of glaucoma in an attempt to lower the intraocular pressure. The surgery involves creating a channel through the sclera, through which intraocular fluid can leave the eye. If scar tissue blocks the exit of the surgically created channel, intraocular pressure rises and the operation fails. Antimetabolites such as 5-Fluorouracil (5-FU) are used to inhibit wound healing to prevent the conjunctiva scarring down on to the sclera. This is an update of a Cochrane review first published in 2000, and previously updated in Objectives To assess the effects of both intraoperative application and postoperative injections of 5-FU in eyes of people undergoing surgery for glaucoma at one year. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMED- LINE (January 1946 to July 2013), EMBASE (January 1980 to July 2013), the metaregister of Controlled Trials (mrct) ( ClinicalTrials.gov ( and the WHO International Clinical Trials Registry Platform (ICTRP) ( We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 25 July We also searched the reference lists of relevant articles and the Science Citation Index and contacted investigators and experts for details of additional relevant trials. Selection criteria We included randomised trials of intraoperative application and postoperative 5-FU injections compared with placebo or no treatment in trabeculectomy for glaucoma. Data collection and analysis Two authors independently assessed trial quality and extracted data. We used standard methodological procedures expected by The Cochrane Collaboration. We contacted trial investigators for missing information. Data were summarised using risk ratio (RR), Peto odds ratio and mean difference, as appropriate. 1

4 The participants were divided into three separate subgroup populations (high risk of failure, combined surgery and primary trabeculectomy) and the interventions were divided into three subgroups of 5-FU injections (intraoperative, regular dose postoperative and low dose postoperative). The low dose was defined as a total dose less than 19 mg. Main results Twelve trials, which randomised 1319 participants, were included in the review. As far as can be determined from the trial reports, the methodological quality of the trials was not high, including a high risk of detection bias in many. Of note, only one study reported low-dose postoperative 5-FU and this paper was at high risk of reporting bias. Not all studies reported population characteristics, of those that did mean age ranged from 61 to 75 years. 83% of participants were white and 40% were male. All studies were a minimum of one year long. A significant reduction in surgical failure in the first year after trabeculectomy was detected in eyes at high risk of failure and those undergoing surgery for the first time receiving regular-dose 5-FU postoperative injections (RR 0.44, 95% confidence interval (CI) 0.29 to 0.68 and 0.21, 0.06 to 0.68, respectively). No surgical failures were detected in studies assessing combined surgery. No difference was detected in the low-dose postoperative 5-FU injection group in patients undergoing primary trabeculectomy (RR 0.93, 95% CI 0.70 to 1.24). Peroperative 5-FU in patients undergoing primary trabeculectomy significantly reduced risk of failure (RR 0.67, 95% CI 0.51 to 0.88). This translates to a number needed to treat for an additional beneficial outcome of 4.1 for the high risk of failure patients, and 5.0 for primary trabeculectomy patients receiving postoperative 5-FU. Intraocular pressure was also reduced in the primary trabeculectomy group receiving intraoperative 5-FU (mean difference (MD) -1.04, 95% CI to -0.43) and regular-dose postoperative 5-FU (MD -4.67, 95% CI to -2.73). No significant change occurred in the primary trabeculectomy group receiving low-dose postoperative 5-FU (MD -0.50, 95% CI to 1.96). Intraocular pressure was particularly reduced in the high risk of failure population receiving regular-dose postoperative 5-FU (MD , 95% CI to ). No difference was detected in the combined surgery population receiving regular-dose postoperative 5-FU (MD -1.02, 95% CI to 0.37). Whilst no evidence was found of an increased risk of serious sight-threatening complications, other complications are more common after 5-FU injections. None of the trials reported on the participants perspective of care. The quality of evidence varied between subgroups and outcomes, most notably the evidence for combined surgery and low-dose postoperative 5-FU was found to be very low using GRADE. The combined surgery postoperative 5-FU subgroup because no surgical failures have been reported and the sample size is small (n = 118), and the low-dose postoperative 5-FU group because of the small sample size (n = 76) and high risk of bias of the only contributing study. Authors conclusions Postoperative injections of 5-FU are now rarely used as part of routine packages of postoperative care but are increasingly used on an ad hoc basis. This presumably reflects an aspect of the treatment that is unacceptable to both patients and doctors. None of the trials reported on the participants perspective of care, which constitutes a serious omission for an invasive treatment such as this. The small but statistically significant reduction in surgical failures and intraocular pressure at one year in the primary trabeculectomy group and high-risk group must be weighed against the increased risk of complications and patient preference. P L A I N L A N G U A G E S U M M A R Y 5-Fluorouracil compared with placebo or no intervention during or after surgery for glaucoma Background Glaucoma involves a loss of vision that may be associated with raised pressure inside the eye. When glaucoma is diagnosed, it is common to try to reduce that pressure with medical, laser or surgical procedures (trabeculectomy). Surgery does not immediately restore vision, and may involve extra vision loss in the short term. Drugs can be used to modify wound healing to improve the likelihood of the success of surgery. Study characteristics 2

5 This is a summary of a Cochrane review that looked at the effect of using one of these drugs, 5-Fluorouracil (5-FU). We gathered evidence from 12 trials involving 1319 participants. The evidence is current to July FU injections after glaucoma surgery For patients who have never had eye surgery before, 5-FU injections after surgery can slightly reduce the pressure in the eye after one year and also the risk of having more surgery in the first year. For patients having both cataract surgery and glaucoma surgery at the same time, no difference has been detected between injections and no injections. Some people are at higher risk of having problems following trabeculectomy, for instance people that have had previous surgery on the eye. For this group, the 5-FU injections can reduce the pressure in the eye a little and also reduce the risk of having more surgery in the first year. Low-dose 5-FU injections after glaucoma surgery Only one study has investigated the effect of using lower than normal doses in the injections. No benefit was found when compared to a control group who had no injections. 5-FU during surgery If 5-Fluorouracil was applied to the eye during the surgery, there was less chance of having to have more surgery within the year and the pressure in the eye was also reduced slightly at one year. Side effects and complications of 5-FU during or after surgery Complications such as damage to cells at the front of the eye or a leak from the wound seem more common when 5-FU is used. Quality of evidence The methodological quality of the trials was not high in general. In many of the studies that contributed to the evidence about 5-FU after glaucoma surgery the researchers were aware of whether the participant had received the dummy injection or the 5-FU injection. This may have introduced bias into the results. Importantly the only study contributing information about low dose 5-FU was of low methodological quality so our conclusions on low dose 5-FU must be cautious. The studies that contributed evidence about 5-FU during surgery was largely very good, the studies were designed and reported to a standard we would expect of modern trials. Conclusions We concluded that the main benefit is for people at high risk of problems. There may be a smaller benefit for people at low risk of problems if 5-FU is given either as injections after surgery or during the operation. However, 5-FU was found to increase the risk of serious complications and so may not be worthwhile for the small benefit gained. 3

6 S U M M A R Y O F F I N D I N G S F O R T H E M A I N C O M P A R I S O N [Explanation] Regular- dose postoperative 5- FU versus control for glaucoma surgery Patient or population: participants with glaucoma surgery Settings: ophthalmic surgery Intervention: regular-dose postoperative 5-FU versus control Outcomes Illustrative comparative risks* (95% CI) Relative effect (95% CI) Assumed risk Corresponding risk Control Regular- dose postoperative 5- FU versus control Failure at 12 months 286 per per 1000 (74 to 166) M ean intraocular pressure at 12 months RR 0.39 (0.26 to 0.58) No of Participants (studies) 469 (6 studies) Quality of the evidence (GRADE) low 1 Comments See comment See comment Not estimable - See comment Due to heterogeneity among studies, results were not pooled. Complications - wound leak Follow-up: 12 months 143 per per 1000 (133 to 291) RR 1.38 (0.93 to 2.04) 469 (6 studies) low 1 Complications - hypotonous maculopathy See comment See comment Not estimable - See comment Only reported in 1 study (Goldenfeld 1994). Complications - shallow anterior chamber Follow-up: 12 months 30 per per 1000 (23 to 135) RR 1.84 (0.76 to 4.46) 469 (6 studies) low 1 4

7 Complications - epithelial toxicity Follow-up: 12 months 433 per per 1000 (589 to 771) RR 1.56 (1.36 to 1.78) 469 (6 studies) * The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). 5- RU: fluorouracil; CI: confidence interval; RR: risk ratio. low 1 GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. M oderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. 1 The quality is reduced by the high or unclear risk of bias in a large number of the trials. 5

8 B A C K G R O U N D Description of the condition Lowering intraocular pressure (IOP) was established as a treatment for glaucoma more than 100 years ago. The lack of evidence that lowering IOP is effective in preventing continued loss of visual function in glaucoma documented by the first systematic review on eye health (Rossetti 1993), led to several definitive studies - the Ocular Hypertension Treatment Study (Kass 2002), the European Glaucoma Prevention Study (Miglior 2005), and the Early Manifest Glaucoma Trial Group (Heijl 2002). These, and subsequent systematic reviews (Maier 2005; Vass 2007), provide evidence that lowering IOP can prevent ocular hypertension and reduce the risk of progression of glaucoma. A review by Burr et al. comparing medical with surgical treatment was inconclusive but the National Institute for Health and Clinical Excellence (NICE) guidelines published in 2009 recommend initial treatment with topical medications (Burr 2012; NICE 2009). However, if more than two medications are insufficient to control the pressure and prevent progression, then trabeculectomy augmented by antimetabolites is recommended though the augmentation itself is not specified (NICE 2009). Trabeculectomy offers no immediate improvement in vision and indeed is often associated with the loss of some detailed vision in the short term. This usually recovers, although in some people there may be a small but permanent reduction in the visual potential of the operated eye. Glaucoma surgery of this type can be conducted under local or general anaesthesia as a day case procedure, but practice varies widely according to local resources and access to follow-up care. The operation involves separating the conjunctiva from the sclera by making an incision at the junction of the cornea and the sclera (on the part of the eye normally hidden under the upper eyelid), to form a conjunctival flap that is folded back to expose the underlying sclera. A half-thickness incision is made into the sclera (usually 4 x 4 mm) at the corneo-scleral junction. The half-thickness scleral flap is raised towards the limbus and a small section of the sclera under the flap is removed (sclerostomy) allowing aqueous to leave the anterior chamber of the eye. The scleral flap is repositioned and loosely sutured. The flap guards the sclerostomy, preventing excessive egress of aqueous, which could result in hypotony (a very soft eye). Finally, the conjunctiva is replaced. Aqueous passes through the sclera and collects under the conjunctiva as a bleb. Fluid in the bleb is absorbed by capillaries and lymphatics within the conjunctiva, or evaporates across the conjunctiva. Final IOP is determined by many factors including the size of the bleb, the thickness of the conjunctiva and how adherent the conjunctiva around the bleb is to the sclera. If the conjunctiva overlying the operation site scars down onto the scleral flap then no aqueous can leave the eye, resulting in the return of raised IOP. Optimum success rates for trabeculectomy are achieved when the eye has not been exposed to previous interventions, either surgical or medical (Lavin 1990). Risk factors for failure of trabeculectomy to control IOP include previous exposure to topical medication (especially sympathomimetic agents such as adrenaline), previous surgical manipulation of the conjunctiva or other injury. Age is inversely related to risk, and being of black African ethnic origin is thought by some surgeons to be a risk factor (Broadway 1994). Other risk factors for failure of first-time trabeculectomy include diabetic status, a diagnosis of pigmentary glaucoma, grade of surgeon, position of traction suture, technique of local anaesthetic and IOP at listing (Edmunds 2004). Description of the intervention 5-Fluorouracil (5-FU) is an antimetabolite that can be applied during or after surgery to prevent the conjunctiva scarring down onto the sclera. Peroperative (intraoperative) 5-FU is usually administered to the sclera before or after the half-thickness scleral flap incision is made often using sponges soaked in the 5-FU solution applied for between two and five minutes. There is some variation in the technique used to deliver 5-FU. Postoperative 5- FU is administered as subconjunctival injections, the dose and regimen varies widely. The patient s experience of glaucoma surgery is not thought to be influenced by the intraoperative use of antimetabolites, although this has not been formally assessed. The addition of a regimen of postoperative injections will significantly affect the patient s experience in terms of numbers of visits and sustained discomfort or pain from the injections. How the intervention might work The investigation of the use of agents to modify the wound-healing process began in the early 1980s with work on 5-FU and Mitomycin C beginning almost simultaneously in different parts of the world. 5-FU is a pyrimidine analogue antimetabolite that blocks deoxyribonucleic acid (DNA) synthesis through the inhibition of thymidylate synthesis. In vitro experiments on these agents are summarised by Blumenkranz The first successful animal model demonstrating the effectiveness of 5-FU in bleb formation in the owl monkey was also reported in 1984 (Gressel 1984). The same group published the findings of a pilot study in humans of the use of 5-FU in glaucoma filtering surgery (Heuer 1984). Shortly thereafter, the Fluorouracil Filtering Surgery Study Group (FFSSG) was established and the first large-scale randomised controlled trial initiated (FFSSG 1992). Subsequent laboratory research indicated that a single intraoperative application of 5-FU might be sufficient to control postoperative proliferation of scar tissue at the drainage site (Khaw 1992). 6

9 Why it is important to do this review There have been no systematic reviews undertaken to summarise the totality of the evidence of the effectiveness of 5-FU. Skuta and Parrish reviewed the role of agents in the modification of wound healing in 1987 in which numerous reports, almost all uncontrolled case series, of outcomes of different drainage techniques in different populations were summarised (Skuta 1987). Parrish s editorial in 1992 called for more randomised controlled trials on the use of antimetabolites in filtering surgery in order to answer important questions on who should and should not receive these agents (Parrish 1992). In reviewing combined glaucoma and cataract surgery in a perspectives article, Shields suggested that antimetabolites might be useful in improving the success of this procedure but again called for more evidence of effectiveness (Shields 1993). A more recent editorial raised valid concerns that the widespread use of antimetabolites in glaucoma surgery had the potential to do as much harm as good and urged caution (Higginbotham 1996). However, Chen s survey in the US and Japan revealed wide variation in practice reflecting the underlying uncertainty over the indications for their usage (Chen 1997). Since this review was originally published, a number of randomised controlled trials have been conducted to examine the effectiveness of this method of application. Consequently the scope of this review was expanded to include intraoperative application of 5- FU as a subgroup in the 2013 update. Clinicians now prefer the intraoperative application of agents for the modification of wound healing and routine postoperative injections of 5-FU are now rarely used. They are, however, used by some people on an ad hoc basis if there are signs of imminent failure of the drainage procedure. Postoperative injections of 5-FU were the first of a planned series of reviews on the use of antimetabolites in glaucoma surgery. We have now divided the reviews according to the intervention tested as follows. 1. Postoperative 5-FU injections versus control; intraoperative 5-FU versus control; indirect comparison of postoperative and intraoperative 5-FU in the absence of any head-to-head comparisons. 2. Intraoperative Mitomycin C versus control (Wilkins 2005). 3. Intraoperative Mitomycin C versus postoperative or intraoperative 5-FU. This review assessed the effects of postoperative 5-FU injections compared with control and intraoperative 5-FU versus control. Peroperative 5-FU was planned as a separate review initially but, in 2012, we decided that it should be included in the postoperative review to create an overall review of 5-FU use with trabeculectomy. O B J E C T I V E S To assess the effects of both postoperative 5-FU injections and the intraoperative application of 5-FU on the success rate of trabeculectomy and to examine the balance of risk and benefit at one year of follow-up. M E T H O D S Criteria for considering studies for this review Types of studies We included only randomised controlled trials. We excluded studies with follow-up less than 12 months. Types of participants We included people with glaucoma and placed no further limitations on participant eligibility. We considered three separate subgroup populations: high risk of failure - people who have had previous glaucoma drainage surgery or surgery involving anything more than trivial conjunctival incision including cataract surgery, glaucoma secondary to intraocular inflammation, congenital glaucoma and neovascular glaucoma; combined surgery - people undergoing trabeculectomy with extracapsular cataract extraction and intraocular lens implant; primary trabeculectomy - people who have received no previous surgical intervention as defined above. This group may include people who have had previous laser procedures. Types of interventions We included trials in which injections of 5-FU were administered at any dose and compared with placebo injections or no injections. We divided the intervention into three subgroups. Postoperative regular-dose 5-FU - greater than 19 mg administered by injection in total in the five weeks following the operation. Postoperative low-dose 5-FU - less than 19 mg administered by injection in total in the five weeks following the operation. Peroperative regular-dose 5-FU (hereafter referred to as intraoperative 5-FU) - greater than 19 mg administered by injection during the operation. Postoperative low-dose 5-FU is considered separately because these are doses lower than are commonly used in clinical practice and the only study using these doses specified a low dose postoperative series (Chaudhry 2000). 7

10 Types of outcome measures Primary outcomes The primary outcomes were the proportion of failed trabeculectomies at 12 months after surgery, and the mean IOP at 12 months. Failure was defined as the need for repeat surgery or uncontrolled IOP (usually more than 22 mm Hg) despite additional topical or systemic medications. Secondary outcomes The secondary outcomes were adverse event rates in either group with reference to: wound leaks - the presence of a positive Seidel test (visible aqueous flow with the tear film stained with fluorescein); hypotony - the IOP is below 5 mm Hg or associated with complications such as macular oedema and sight loss or choroidal detachments; late endophthalmitis - an infection of the globe contents that even with prompt aggressive treatment often results in substantial loss of visual function. Late here implies infection arising from organisms gaining access to the globe through thinwalled drainage blebs or frank breaks in the conjunctival epithelium after the immediate postoperative period when infectious agents may have entered the eye during the surgical procedure; expulsive haemorrhage - choroidal haemorrhage, usually during the early postoperative period while the eye is still soft, leading to a marked rise in IOP; shallow anterior chamber - prolonged shallowing of the anterior chamber giving rise to concern over possible contact of the lens with the cornea and occurring as a result of excessive drainage or choroidal effusions or both leading to anterior displacement of the ciliary body, iris and lens; corneal and conjunctival epithelial erosions - punctate or confluent epithelial staining with fluorescein due to damage to the ocular epithelial surface; other complications reported in individual trials. Other definitions for general eye-related terms can be found in the glossary contained within the Eyes and Vision Group module of The Cochrane Library. Search methods for identification of studies Electronic searches We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 6, part of The Cochrane Library. (accessed 25 July 2013), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMED- LINE (January 1946 to July 2013), EMBASE (January 1980 to July 2013), the metaregister of Controlled Trials (mrct) ( ClinicalTrials.gov ( and the WHO International Clinical Trials Registry Platform (ICTRP) ( We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 25 July See: Appendices for details of search strategies for CENTRAL (Appendix 1), MEDLINE (Appendix 2), EMBASE (Appendix 3), mrct (Appendix 4), ClinicalTrials.gov (Appendix 5) and the ICTRP (Appendix 6). Searching other resources We searched the reference lists of identified trials to find additional trials. We used the Science Citation Index to find studies that had cited the identified trials. We contacted the investigators of the identified trials and practitioners who are active in the field to identify additional published and unpublished studies. Data collection and analysis Selection of studies Two authors independently screened the titles and abstracts resulting from the searches. We obtained the full copies of any report referring to possibly or definitely relevant trials. We assessed all full copies according to the definitions in the Criteria for considering studies for this review. We assessed only trials meeting these criteria for methodological quality. Data extraction and management We independently extracted data using a form developed by the Cochrane Eyes and Vision Group (available from the editorial base). We resolved any discrepancies by discussion. Assessment of risk of bias in included studies In the 2013 update, we included Risk of bias tables and figures and Summary of findings tables. We assessed risk of bias for each trial according to Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Risk of bias did not determine inclusion in the synthesis. We assessed sequence generation, allocation concealment, masking, loss to follow-up and selective outcome reporting bias for each trial as being at high, unclear or low risk of bias. We contacted study authors for clarification when the risk of bias was unclear in the trial report. 8

11 Unit of analysis issues The unit of analysis was not limited provided that each eye was randomised separately. Injected 5-FU and peroperative 5-FU is not thought to act systemically. The unit of analysis for each study is documented in the Characteristics of included studies section. Dealing with missing data Where information regarding results or methodology was missing or unclear, we contacted the original authors. If they did not respond the authors evaluated what data could be included on a case by case basis. The inclusion and exclusion of studies is detailed in the Results of the search section. Assessment of heterogeneity We assessed heterogeneity using the Chi 2 test and the I 2 statistic as described in Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011), where a rough threshold of I 2 > 50% represents substantial heterogeneity. Subgroup analysis was not conducted to explore heterogeneity as none were prespecified and would be of limited value. Assessment of reporting biases Funnel plots were not created to assess reporting bias because there were too few studies in each subgroup (fewer than 10) (Higgins 2011). We considered possible sources of reporting bias including funding, publication of articles and affiliation of study authors with manufacturers. Where sources of bias were identified, we reported this in the Risk of bias table. Sensitivity analysis In 2013, we updated the sensitivity analyses following new recommendations in Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011) and consequently deviated from the protocol. We conducted a sensitivity analysis to analyse the effect of including studies with any aspect of high or unknown risk of bias using the new Risk of bias assessment method described above. Summary of findings The findings of the review were summarised using the recommendations in Chapter 10 of the Cochrane Handbook for Systematic Reviews of Interventions (Sterne 2011). Each Summary of findings table is limited to one population group and reports the primary outcomes and key secondary outcomes. For each outcome, we reported the quality of the evidence, determined using GRADE. This classifies the evidence as high, moderate, low or very low, an explanation of the broad significance of each grade is found at the bottom of each Summary of finding table (Summary of findings for the main comparison). This grade of evidence is reduced if there are limitations to the design or implementation of studies, heterogeneity, imprecision of results (wide confidence intervals (CIs)) or a high probability of publication bias. If the evidence is graded less than high, an explanation is provided in the comments or footnotes. R E S U L T S Description of studies Data synthesis We summarised data for the probability of failure and common side effects using risk ratios (RR). We summarised data for mean IOP using the mean difference (MD). We used the Peto odds ratio to summarise data for rarer events such as complications. We provide 95% confidence intervals (CIs) for all results. We conducted separate analyses for regular-dose and low-dose 5- FU trials as defined above and calculated summary estimates for each of the three subgroup populations. We used the random-effect model unless there were too few studies to estimate an effect in which case a fixed-effect model was used. In the absence of any head-to-head comparison of postoperative and intraoperative 5-FU a post-hoc indirect comparison between subgroups was conducted according to Borenstein 2008 using the I 2 statistic to determine if any difference was due to subgroup differences or sampling error. Results of the search The original electronic searches revealed more than 70 studies. Two trials were excluded because reported follow-up was less than 12 months (Hennis 1991; Lamba 1996). A further three trials were found not to meet the inclusion criteria when the full report was assessed, and were, therefore, excluded (Hefetz 1994; Lee 1996; Oh 1994). Seven randomised controlled trials met the review inclusion criteria. Scanning the reference lists of the reports revealed one further study (Loftfield 1991), which was published only as an abstract. As attempts to contact the authors were fruitless and no further information could be obtained about the study, Loftfield 1991 was excluded from the review s analysis. However, we have reported the complications described by Loftfield 1991 below because of the paucity of other research at low-doses of 5-FU and to highlight the risk of complications at lower doses. One further trial was identified in the update search in 2001 (Chaudhry 2000). Contact with the authors of identified trials and with researchers 9

12 who are active in the field did not identify any further relevant studies. Communication with practitioners in 2005 revealed an abstract in the proceedings of the American Academy of Ophthalmology (Baez 1993). The abstract reported a trial in which 72 patients undergoing combined cataract and trabeculectomy were randomised to receive postoperative 5-FU or nothing. The abstract reported no difference in outcome with increased adverse events in the intervention arm. We have been unable to find a subsequent published report of this trial and our attempts to contact the authors have been unsuccessful and it has, therefore, been excluded. Buzarovska 2005 was also identified in 2005 but it did not randomise patients and so was excluded. Gandolfi 1997 was excluded because it matched participants undergoing combined cataract and trabeculectomy before randomisation. An updated search was done in October 2008, which yielded a further 90 reports of studies. The Trials Search Co-ordinator scanned the search results and removed any references that were not relevant to the scope of the review. The search did not identify any references that met the inclusion criteria for the review. With the revision of the review in 2013, we included trials that used 5-FU both intraoperatively and postoperatively. We redesigned and re-ran the searches to reflect the change in the scope of the review and have included a PRISMA flow diagram showing the amended status of the review (Figure 1). There are currently 12 included studies in the review and 13 excluded studies. There are three studies awaiting classification (see Characteristics of studies awaiting classification for details). During this update, we also obtained a full copy of Donoso 1998, which had previously been unavailable. The report of the trial has been translated and included in the review. 10

13 Figure 1. Update results combining searches for intraoperative and postoperative use of 5-Fluorouracil. 11

14 Included studies The following is a summary of the main features of the eight included studies for postoperative 5-FU and the five trials for intraoperative 5-FU. Further details can be found in the Characteristics of included studies table. Altogether, the 12 trials randomised 1023 eyes of 1319 participants. One peroperative study (Leyland 2001) included both eyes of four participants, each eye was randomised separately, two participants received 5-FU and placebo, one received 5FU only, and one received placebo only. POSTOPERATIVE 5-FLUOROURACIL INTRAOPERATIVE 5-FLUOROURACIL Types of participants Five trials randomised 770 patients (Donoso 1998; Khaw 2002 (the Moorflo trial); Leyland 2001; Wong 2009; Yorston 2001). These trials were all related to each other through a collaborative network. They were all conducted on patients undergoing primary trabeculectomy for either chronic open-angle glaucoma or chronic-angle closure glaucoma. Two trials were conducted in the UK, one in Chile, one in Tanzania and one in Singapore. Types of participants The seven postoperative trials randomised 549 participants. Trials reported participants from three subgroups: those at high risk of failure (FFSSG 1989; Ruderman 1987), those undergoing combined cataract and trabeculectomy (O Grady 1993; Wong 1994), and those undergoing trabeculectomy for the first time after failure to control IOP with medical intervention (Chaudhry 2000; Goldenfeld 1994; Ophir 1992). Six of the studies were conducted in the USA and one in Israel. Types of intervention 5-FU was administered in 5 mg injections in 0.1 or 0.5 ml saline solution. The schedule for injections varied across the trials with a mean total of five injections administered postoperatively. The schedule of injections for respective studies is presented in Table 1. Chaudhry 2000 reported the use of lower doses of 5-FU with three 5 mg postoperative injections or fewer. Data for trials are presented separately according to whether regular dose or low dose 5-FU was used. All studies compared 5=FU with no intervention. None used placebos. Types of outcome measure All of the trials reported success rates at between 12 and 25 months follow-up. The exact definitions of success varied across trials but control of IOP at or below 21 mm Hg with or without medications is an inclusive definition. All but one trial (FFSSG 1989), reported mean and standard deviation IOP pressure at 12 months. Complications reported in the trials included corneal epithelial toxicity, wound leaks, choroidal effusions, supra choroidal haemorrhage, hypotony and hyphaema. None of the trial reports has provided any outcomes from the participants perspective. Types of intervention Yorston 2001 and Leyland 2001 published small studies on using 5-FU intraoperatively during trabeculectomy at a dose of 25 mg per ml for five minutes after exposure of the sclera. Both of these were placebo controlled with the surgeons unaware whether the moistened sponge applied to the sclera contained 5-FU or normal saline. Khaw 2002 published a report of the largest trial as an Association for Research in Vision and Ophthalmology (ARVO) abstract in 2002 but there is, as yet, no peer-reviewed published report of this trial in the literature. Unpublished data from this trial have been obtained however. The Singapore 5-FU trial first reported its results in an ARVO abstract in 2005 and the results were published in 2009 (Wong 2009). Both of these latter studies and Donoso 1998 used a higher dose of 50 mg 5-FU for five minutes and were also double blinded placebo controlled. Types of outcome measure Various outcome measures were reported but through contact with the authors, it has been possible to retrieve outcomes included in this review. Excluded studies See Characteristics of excluded studies for further details. Risk of bias in included studies The risk of bias assessment is summarised in Figure 2 and Figure 3 and the details of each decision are described in the Characteristics of included studies section. 12

15 Figure 2. Risk of bias graph: review authors judgements about each risk of bias item presented as percentages across all included studies. 13

16 Figure 3. Risk of bias summary: review authors judgements about each risk of bias item for each included study. 14

17 We have attempted to contact trialists to obtain further information where there was insufficient information to determine the risk of bias. To date, we have received a response from Chaudhry 2000 and FFSSG 1989, and this information has been integrated into the risk of bias assessment. We have been unsuccessful in contacting Donoso 1998; O Grady 1993; Ophir 1992; Ruderman 1987; and Wong Allocation The allocation concealment was thought to be adequate only in Chaudhry 2000; Donoso 1998; FFSSG 1989; Khaw 2002; Leyland 2001; Wong 2009; and Yorston Allocation concealment was unclear in the remaining five. In the absence of information about the randomisation process, O Grady 1993; Ophir 1992; and Ruderman 1987 have been categorised as unclear risk of bias. Blinding Masking was often inconsistent, in Chaudhry 2000, surgeons were masked to the treatment allocation during the operation to reduce performance bias; however, there was no masking of assessors when the outcomes were recorded introducing possible detection bias. There was no record of masking in Goldenfeld 1994; O Grady 1993; Ophir 1992; Ruderman 1987; or Wong This omission is interpreted by the authors to indicate that it probably did not occur and consequently it is thought that both performance and detection bias could have occurred. It was thought that there was a low risk of performance or detection bias in studies that took precautions by masking the surgeons and outcome assessors. Some particularly well-designed studies also masked patients (Khaw 2002; Leyland 2001). Others only masked assessors and did not mask patients (Donoso 1998; FFSSG 1989; Yorston 2001), these studies were still classed as low-risk because the objective outcomes make it difficult for a patient to introduce bias. No study described whether researchers were masked during analysis. Selective reporting Insufficient information was provided to judge whether prespecified outcomes had been reported in Donoso 1998; O Grady 1993; Ophir 1992; Ruderman 1987; and Wong 1994, therefore we judged these to be at an unclear risk of bias. However, the reported outcomes appeared appropriate and in keeping with the intervention and aims of the studies. The risk was low in all other studies. Other potential sources of bias The FFSSG study was terminated early by an independent ethics committee. This may have introduced bias in either direction but most likely an overestimate of effect (according to Briel 2012). Effects of interventions See: Summary of findings for the main comparison Regulardose postoperative 5-Fluorouracil versus control for glaucoma surgery; Summary of findings 2 Regular-dose postoperative 5-Fluorouracil versus control for glaucoma surgery - high risk of failure subgroup; Summary of findings 3 Regular-dose postoperative 5-Fluorouracil versus control for glaucoma surgery - combined surgery subgroup; Summary of findings 4 Regulardose postoperative 5-Fluorouracil versus control for glaucoma surgery - primary trabeculectomy subgroup; Summary of findings 5 Low-dose postoperative 5-Fluorouracil versus control for glaucoma surgery; Summary of findings 6 Intraoperative 5-Fluorouracil versus placebo or control for glaucoma surgery Regular-dose postoperative 5-Fluorouracil versus control Failure at 12 months (Analysis 1.1) Incomplete outcome data It is known that patients with unfavourable results were excluded from Chaudhry 2000 and Ophir The risk of attrition bias could not be determined in O Grady 1993 or Ruderman A substantial number were lost to follow-up in Donoso 1998 and Yorston 2001, and, although this seemed to be distributed equally between the control and intervention group, there is a possible risk of attrition bias. The reason for these losses is unclear, although, in both cases, it is thought to reflect the research environment in these countries (Chile and Tanzania). High risk of failure Two trials randomised 239 participants (FFSSG 1989; Ruderman 1987). The results show an apparent benefit of 5-FU injections (RR 0.44, 95% CI 0.29 to 0.68) or a point estimate of a 56% reduction in the risk of failure. A larger effect was observed in the Ruderman study despite a smaller overall dose being given. The CIs for this study are much wider as a result of the small sample size (Analysis 1.1). 15

18 Combined surgery Two trials randomised 118 participants (O Grady 1993; Wong 1994). No failure at 12 months was reported in either the control or treatment arm by O Grady 1993 or Wong Primary trabeculectomy Two trials randomised 112 participants (Goldenfeld 1994; Ophir 1992). The point estimate of RR for failure in the 5-FU group was 0.21 (95% CI 0.06 to 0.68), a 79% reduction in risk of failure and statistically significant. The individual studies found no statistically significant effect, but when the results are pooled, a significant effect was observed (Analysis 1.1). Mean intraocular pressure at 12 months (Analysis 1.2) High risk of failure Only one study reported the mean and standard deviation of IOP and so meta-analysis could not be performed. Ruderman 1987 found a mm Hg difference between treatment and control arms (95% CI to 18.63). Combined surgery The pooled estimate of effect for the two trials was a reduction of 1.02 mm Hg in the 5-FU group (95% CI 0.37 to 2.40), but the CI crosses the line of no effect. Primary trabeculectomy Mean IOP reduction in the two trials is similar. The pooled estimate of effect is a reduction of 4.67 mm Hg in the 5-FU group (95% CI 2.74 to 6.60) (Analysis 1.2). Wound leak The risk of wound leak was increased for the high risk of failure 5-FU group (RR (random-effects) 1.64, 95% CI 1.04 to 2.58). The CI crosses the line of no effect for the combined surgery and primary trabeculectomy groups (Table 2). Hypotonous maculopathy Hypotonous maculopathy was reported as a complication in one participant in one trial in the higher dose primary trabeculectomy group (Goldenfeld 1994). The estimated risk is raised for the 5- FU treated participants at approximately a three-fold increase (RR 2.82, 95% CI 0.12 to 66.62). However, these events are rare and the CIs around this estimate are wide (Table 2). Late endophthalmitis Late endophthalmitis was not reported in any of the trials within 12 months follow-up; therefore, the risk cannot be estimated. Expulsive haemorrhage Expulsive haemorrhage was reported only in trials on participants in the high risk of failure group. Similar numbers were seen in both treatment groups in both studies. This is probably an underlying risk of the surgical procedure on eyes that were already damaged from previous surgery or inflammation or may reflect the higher baseline IOP in this group (Table 2). Shallow anterior chamber Shallow anterior chamber was inconsistently reported in the trials as a complication. The definition varied from study to study. No consistently increased risk was observed for people receiving 5-FU (Table 2). Epithelial toxicity Epithelial toxicity was observed in all studies and the risk was always greater in the 5-FU group and the RR was statistically significant in several studies. The size of the effect varied considerably, which may reflect differences in the site and method of injection and the overall dose given. None of the trials reported a lasting ocular surface disturbance so that the use of the antimetabolite does not appear to be a serious complication. However, the discomfort caused by this adverse effect is likely to have had a major impact on the participants experience of treatment. As already stated, participants experience of treatments were not reported in any of the studies (Table 2). Numbers needed to treat to obtain an additional beneficial outcome There was a statistically significant reduction in the risk of failure for the high-risk group of 24% (95% CI 13% to 35%) and 20% (95% CI 7% to 33%) for the primary trabeculectomy group. This translates to a NNTB of 4.1 for the high risk of failure patients, and 5.0 for primary trabeculectomy patients. There were no events in the combined surgery group. Lower-dose postoperative 5-Fluorouracil versus control Chaudhry 2000 only included participants undergoing primary trabeculectomy. 16

19 Main outcome measures Chaudhry 2000 found no evidence of a difference in failure rates or a difference in the mean number of postoperative pressure controlling medications used in either group (Table 3). Mean reduction in IOP was very similar in both groups (11.5 ± 9.1 mm Hg 5-FU, 10.2 ± 8.7 mm Hg control) and this was not statistically significant. Wound leak One instance of wound leak occurred in the control group, this difference was not statistically significant, (RR 0.33, 95% CI 0.01 to 7.93). Additional complications The other secondary outcomes of hypotonous maculopathy, late endophthalmitis, expulsive haemorrhage and epithelial toxicity were not reported. Chaudhry 2000 did, however, report cataract, choroidal drainage (presumably for persistent choroidal detachment) and bleb encapsulation (Table 3). None reached statistical significance although the point estimate for cataract was large (RR 6.00, 95% CI 0.76 to 47.49; risk difference 13%, 95% CI 0% to 26%; number needed to treat for an additional harmful outcome (NNTH) 8). Although only published as an abstract and not included in this review s analysis it is noteworthy that Loftfield 1991 reported a substantial but not statistically significant increase in risk of hypotonous maculopathy in the 5-FU group (RR 7.88, 95% CI 0.45 to 137.8; risk difference 17%, 95% CI 0.0% to 34%; NNTH 6). Loftfield 1991 also reported a substantial increased RR of epithelial toxicity of (95% CI 1.14 to ; risk difference 43%, 95% CI 23% to 64%; NNTH 2). Intraoperative 5-Fluorouracil versus control Main outcome measures (Analysis 3.1; Analysis 3.2) The point estimate risk reduction of failure at one year was quite substantial at 0.67 (95% CI 0.51 to 0.88) (Analysis 2.1), and this effect is mainly due to the Khaw 2002 results. The difference in effect estimates of the different trials did not reflect the lower dose of 5-FU used in Leyland 2001 and Yorston For the mean differences in IOP at one year, there was a small overall reduction in IOP of 1.04 mm Hg (95% CI 0.43 to 1.65), which is probably not clinically significant but is nevertheless statistically different. There was no heterogeneity (Analysis 2.2). Wound leak 5-FU caused a 50% increase in the RR of wound leak, which is just significant with the summary estimate with no statistical heterogeneity or apparent dose-related response (Table 2). Hypotonous maculopathy Only Khaw 2002 reported hypotonous maculopathy, which was slightly more common in the 5-FU arm. Late endophthalmitis and expulsive haemorrhage The secondary outcomes of late endophthalmitis and expulsive haemorrhage were not reported by any study of intraoperative 5- FU and, therefore, risk cannot be estimated. Shallow anterior chamber 5-FU significantly increased the risk of anterior chamber shallowing (Table 2). However there was heterogeneity observed with the Singapore trial observing an opposite risk (Wong 2009). Epithelial toxicity Only reported in the Leyland 2001 and Wong 2009 trials and in only the latter was it commonly reported being slightly more frequent in the 5-FU arm (Table 2). Number needed to treat for an additional beneficial effect There was a statistically significant reduction in the risk of failure in the intraoperative 5-FU subgroup of 9% (95% CI 15% to 3%), which translates into an NNTB of 11. Intraoperative 5-Fluorouracil versus postoperative 5- Fluorouracil In the absence of any head-to-head trials a post-hoc indirect comparison was conducted (Analysis 3.1; Analysis 3.2; Figure 4). Postoperative 5-FU reduces IOP more than intraoperative 5-FU when used in an equivalent population, in this case primary trabeculectomy, mean difference (95% CI to -2.74) and (95% CI to -0.43) respectively (I 2 = 63%). The confidence intervals do not overlap and so it is statistically significant. The large I 2 statistic confirms that this is likely to be due genuine subgroup differences rather than sampling error (Borenstein 2008). Postoperative and intraoperative 5-FU have a similar reduction on risk of failure however, risk ratio 0.21 (95% CI 0.06 to 0.68) and 0.67 (95% CI 0.51 to 0.88) respectively (I 2 = 27%). This should be interpreted cautiously as it was a post-hoc calculation. 17