Cost-utility of routine cataract surgery Rasanen P, Krootila K, Sintonen H, Leivo T, Koivisto A M, Ryynanen O P, Blom M, Roine R P

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1 Cost-utility of routine cataract surgery Rasanen P, Krootila K, Sintonen H, Leivo T, Koivisto A M, Ryynanen O P, Blom M, Roine R P Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology The authors studied routine cataract surgery. Type of intervention Treatment. Economic study type Cost-utility analysis. Study population The study population comprised patients presenting initially to an ophthalmologist and who were later referred for routine cataract operation. To maintain a real world setting, the authors did not define specific inclusion and exclusion criteria but instead used the "individual ophthalmologists' assessment of the patients' subjective seeing problems and objective signs concerning visual acuity (VA) and presence of signs of cataract". Setting The setting was secondary care (Helsinki University Eye Hospital). The economic study was carried out in Finland. Dates to which data relate The effectiveness and cost data related to the period 2002 to Link between effectiveness and cost data The costing was carried out prospectively on the sample same of patients as that used in the effectiveness study. Study sample The authors did not report that power calculations were carried out to estimate the optimal number of patients to be included within the trial. Instead, they included all patients scheduled for routine cataract operation within the study setting between August 2002 and June Of 386 patients, 88% agreed to participate and returned baseline questionnaires. A total of 219 cataract patients were finally analysed for the study. The patients were divided into three sub-groups for within-group comparisons. Group A comprised 87 patients (56% female) with one eye operated. Group B comprised 73 patients (71% female) with both eyes operated. Group C comprised 59 patients (71% female) whose first eye had been operated on earlier. The mean age of the patients was 69 years in group A, 70 years in group B and 75 years in group C. Study design The authors designed a before-and-after (within-group) study. The analysis was carried out at a single centre. Blinding Page: 1 / 5

2 was not relevant as there was no actual comparison group of patients. Questionnaires were completed at baseline and 6 months after the cataract operation. A total of 282 patients completed a follow-up questionnaire and were available for analysis. Seven cases were removed for incomplete data, 32 for filling in the questionnaire after the operation, 6 for completing the follow-up questionnaire after the operation of the second eye, 7 for receiving more complicated surgery, and 11 because their final principle diagnosis was not cataract. Analysis of effectiveness VA and health-related quality of life (HRQoL) were used as measures of health benefit. VA was measured as bestcorrected visual acuity before the operation using the Snellen notation at 6 metres. Quality of life was measured by the 15D HRQoL questionnaire (see the 'Measures of Benefit Used in the Economic Analysis' section below for further details). Effectiveness results VA was measured only before the trial; measurements afterwards were taken by the referring ophthalmologists and so were not included in the trial results. VA measured by the Snellen index was converted into the logarithm of minimum angle of resolution (LOGMAR). There were no significant differences between groups in the mean best-corrected VA in the surgical eye. There was a significant difference between groups A and B and between groups B and C for the mean best-corrected VA in the non-surgical eye. Clinical conclusions The authors did not draw conclusions about the VA results. In part this was due to the inability to collect postoperative results. However, while VA data represent a measure of health status, they do not reflect the patients' true HRQoL. Measure of benefits used in the economic analysis Quality of life, as measured by the HRQoL questionnaire, was used as the summary measure of health benefit. The 15D HRQoL questionnaire is a generic, 15-dimensional (moving, seeing, hearing, breathing, sleeping, eating, speech, eliminating, usual activities, mental function, discomfort and symptoms, depression, distress, vitality, and sexual activity) standardised and self-administered instrument. It was completed by patients in the trial. Data from patients on their health states were applied to utility weights for the HRQoL taken from the general public. Any HRQoL gain associated with treatment was assumed to last until the end of the patient's remaining statistical life expectancy. This enabled quality-adjusted life-years (QALYs) to be estimated. The QALYs were discounted at a rate of 5%. Direct costs The costing was carried out from the perspective of the secondary health care provider. It centred on all costs incurred by the patient whilst in hospital, including both pre- and postoperative outpatient visits to the eye hospital. These data were sourced from the Econmed clinical patient administration system (Datawell Ltd., Finland), which stores all treatment costs for each patient in the hospital. The cost data were collected for 2002/03. The authors explicitly noted that the costs of visits to the referring ophthalmologist were not included in this analysis. The costs were discounted at a rate of 5%. Statistical analysis of costs The cost results were presented as mean values with standard deviations (SDs), mean values with 95% confidence intervals (CIs), or as median values. Continuous cost variables were compared using a one-way analysis of variance and post-hoc comparisons with independent sample t-tests. Page: 2 / 5

3 Indirect Costs Productivity costs were not relevant to the perspective adopted. Currency Euros (EUR). Sensitivity analysis The authors used a sensitivity analysis to explore the impact of uncertainty in the discount rate, the effectiveness rate and costs on the results. The discount rate was varied between 1 and 5%, while the effectiveness and costs were limited by the upper and lower values of their 95% CIs. The authors used bootstrapping with 10,000 resamples to understand the impact of uncertainty on cost-utility. Estimated benefits used in the economic analysis For group A, the HRQoL was 0.85 (SD=0.13) at baseline and 0.85 (SD=0.14) at 6 months after surgery. The difference was 0.00 (SD=0.14), (p=0.852). For group B, the HRQoL was 0.80 (SD=0.13) at baseline and 0.83 (SD=0.14) at 6 months after surgery. The difference was 0.03 (SD=0.14), (p=0.001). For group C, the HRQoL was 0.82 (SD=0.11) at baseline and 0.81 (SD=0.13) at 6 months after surgery. The difference was (SD=0.07), (p=0.279). The mean QALYs gained were (SD=0.9421) for group A, (SD=1.1966) for group B and (SD=0.7424) for group C. Cost results The mean costs at 6 months were EUR 1,318 (SD=184) for group A, EUR 2,289 (SD=266) for group B and EUR 1,323 (SD=361) for group C. Synthesis of costs and benefits The mean cost per QALY gained was EUR 8,212 for group A, EUR 5,128 for group B, and could not be established due to the fall in QALYs for group C. The results were shown to be relatively robust to variations in the discount rate and cost and effect when varied within the limits of the 95% CIs. However, the authors reported more sensitivity when parameters were varied using their median values. Authors' conclusions "The utility gain observed as the results of routine cataract surgery was small and confined mainly to an improvement in seeing only." The cost per quality-adjusted life-year (QALY) was higher than had previously been estimated. CRD COMMENTARY - Selection of comparators The authors assessed cataract eye surgery. As there was no comparator technology, they compared this with the hypothetical scenario of no treatment. Readers must consider whether no treatment represents a realistic comparator in their own setting. It may be that deferred treatment represents a more realistic alternative, in which case the authors' stratification of the results according to degree of visual impairment symptoms is an especially useful analysis. Page: 3 / 5

4 Validity of estimate of measure of effectiveness The authors used a before-and-after analysis rather than a randomised controlled trial because they wanted the trial, as far as possible, to reflect the nature of treatment in a true clinical setting. Therefore, rather than attempting to control for possible confounding factors, the authors allowed factors that might influence treatment in the real world setting to also influence treatment outcomes in their trial. The study sample included patients referred for cataract surgery and so was an accurate reflection of the study population. There were some patients in whom cataract was not the primary diagnosis and the authors noted the importance of this in their discussion. Loss to follow-up was clearly explained to the reader, thereby improving the validity of the study. An appropriate statistical analysis of the clinical data was carried out to help understand and interpret the uncertainty in the clinical results. However, gathering and reporting postoperative VA data would have greatly improved the usefulness of the results, both for this study and for interpretation by others. Validity of estimate of measure of benefit The authors used HRQoL to measure the impact of surgery on quality of life. The data were measured directly during the clinical study and applied to published utility data. The use of a generic measure facilitates comparisons with a broad range of health-related technologies. Validity of estimate of costs The costing analysis was carried out from the perspective of the secondary care provider. The source of the data ensured that costs relevant to this perspective were included. However, it was unclear whether such costs included overhead costs as well as more direct costs. The sensitivity analysis around the cost estimate improves the readers' understanding, and hence confidence in the results presented, and also improves the generalisability of the results. The costs were appropriately discounted. The authors could have provided a more detailed breakdown of the costs to facilitate the understanding of the main cost drivers. Other issues The authors made useful comparisons of their results with those from other studies. They also noted the real world nature of this study as being an explanation for some of the observed differences. In particular, the authors found cataract surgery to be less cost-effective than had previously been observed. Differences in the methodology underlying the estimation of utility gain were offered as a further explanation of differences. Although the generalisability of the study was not explicitly discussed, the use of extensive sensitivity analyses will have greatly improved the relevance of the results from this study. The authors reported their results thoroughly, providing an appropriate breakdown for different patient sub-populations. This additional information may help to inform policy on the optimal timing of cataract surgery. Several limitations were discussed, these included the assumption that utility gain from surgery lasts until the end of the patient's life, which may lead to an underestimate of the true cost per QALY. Implications of the study The authors agued that "to justify resource use on cataract surgery, the patient has to have definitive medical indications for the surgery or its cost-effectiveness needs to be proven with clear paybacks in the form of improved quality of life". Source of funding Funded by grants from the Helsinki and Uusimaa Hospital Group. Bibliographic details Rasanen P, Krootila K, Sintonen H, Leivo T, Koivisto A M, Ryynanen O P, Blom M, Roine R P. Cost-utility of routine cataract surgery. Health and Quality of Life Outcomes 2006; 4(74) PubMedID Page: 4 / 5

5 Powered by TCPDF ( DOI / Other publications of related interest Because readers are likely to encounter and assess individual publications, NHS EED abstracts reflect the original publication as it is written, as a stand-alone paper. Where NHS EED abstractors are able to identify positively that a publication is significantly linked to or informed by other publications, these will be referenced in the text of the abstract and their bibliographic details recorded here for information. The 15D(C) health-related quality of life (HRQoL) instrument. Available at: URL: lt;url/& gt; Indexing Status Subject indexing assigned by NLM MeSH Aged; Aged, 80 and over; Cataract Extraction /economics /psychology /utilization; Cost-Benefit Analysis; Female; Finland; Hospital Costs; Hospitals, Special /economics; Humans; Male; Middle Aged; Ophthalmology /economics; Outcome Assessment (Health Care) /statistics & numerical data; Prospective Studies; Quality of Life; Quality-Adjusted Life Years; Surveys and Questionnaires; Uncertainty; Visual Acuity AccessionNumber Date bibliographic record published 31/07/2007 Date abstract record published 31/07/2007 Page: 5 / 5