Evidence review. Oesophageal multichannel intraluminal. measurement CEP10028

Transcription

1 Evidence review Oesophageal multichannel intraluminal impedance and ph measurement CEP10028 March 2010

2 Contents 2 Summary... 3 Introduction... 5 Methods... 9 Evidence review Economic issues Conclusions Acknowledgements Glossary References Appendix 1: Supplier contact details Author and report information... 24

3 Summary 3 Oesophageal Intra-luminal Impedance-pH devices Oesophageal multichannel intra-luminal impedance and ph (MII-pH) devices have been developed to measure the incidence and severity of gastro-oesophageal reflux. They consist of a wired catheter containing a ph sensor and impedance channels connected to a data storage system. The catheter is inserted through the nose to the required position and impedance-ph measurements are recorded on an out-patient basis typically over a period of 24 hours. Oesophageal MII-pH devices also have software which allows manual and automatic evaluation of the impedance-ph measurements and correlation to patient symptoms. This allows the diagnosis of non-acid reflux that cannot be detected using conventional methods. Field of use Gastro-oesophageal reflux disease (GORD) is a chronic condition that occurs when the stomach contents reflux into the oesophagus causing troublesome symptoms such as heartburn and potential complications. It is estimated that approximately % of the western population have troublesome reflux symptoms at least once a week. National guidance NICE guidelines published in August 2004 (Management of dyspepsia in adults in primary care) recommend the long term treatment of GORD using proton pump inhibitor (PPI) drugs. Diagnosis of suspected GORD is largely undertaken in primary care based on the symptoms of the patient. The British Society of Gastroenterology (BSG) produced guidelines in 2006 on The use of oesophageal manometry and ph monitoring, but did not include guidelines on the use of MII-pH as it was concluded that the clinical role of MII-pH had yet to be defined. Evidence reviewed This evidence review assesses the capability and appropriate diagnostic use of oesophageal MII-pH devices for patients who have persistent troublesome symptoms while being treated for GORD. A systematic literature search was undertaken and information was requested from three UK based suppliers of MII-pH devices. CEP s verdict No high quality evidence was found to support the use of MII-pH measurements in patients who have persistent symptoms whilst being treated for GORD. The remaining studies, while of poor quality, suggest that there may be a role for MII-pH

4 Summary 4 measurements. Good quality studies by early adopters of the technology are required to confirm its efficacy and determine optimum testing protocols prior to widespread use.

5 Introduction 5 Current clinical practice GORD is a chronic, common condition and one of the most frequent causes of heartburn. GORD is due to the stomach contents backwashing into the oesophagus and can cause significant quality of life impairment and other complications such as oesophagitis (inflammation of the oesophagus) or Barrett s oesophagus (abnormal changes in the cells at the lower end of the oesophagus) (figure 1). It is estimated that approximately % of the western population have reflux symptoms at least once a week [1]. Figure 1. Reflux into the oesophagus Diagnosis of suspected GORD is usually made in primary care by a general practitioner based on the patient s symptoms and is rarely confirmed using endoscopy. Endoscopy is a technique used in GORD to examine the internal surface of the oesophagus by passing a viewing instrument through the nose and down into the oesophagus. In the absence of a confirmed diagnosis, NICE recommends trials of proton pump inhibitor (PPI) drugs to suppress gastric acid secretion as a first line treatment, along with lifestyle advice aimed at reducing the patient s symptoms [2]. While PPI drugs and lifestyle advice can be effective in controlling symptoms for many patients, some will remain symptomatic while on treatment. A recent UK cross-sectional survey concluded that 61% of patients on long term PPI drugs (longer than 12 months) suffered continuing moderate or severe symptoms [3]. With an estimated 1 2% of the western population on long term PPI drugs [3], this equates to potentially 1 million people in the UK suffering from significant quality of life impairment. Excluding patients who do not take their medication, the three most likely reasons for continuing symptoms are: poor suppression of gastric acid by medication; reflux of non-acid gastric content; symptoms being unrelated to reflux. Patients with poor suppression of gastric acid may be treated by increasing the dose of PPI or with alternative medication, those with non-acid reflux may require surgery, and patients whose symptoms are not caused by reflux may require further investigations.

6 Introduction 6 Further medications for GORD are recommended by NICE for patients unresponsive to PPI drugs. It is difficult to improve the symptoms of patients who do not respond to medication and lifestyle advice in the absence of further diagnostic testing. In these patients, it is often unclear whether symptoms are caused by inadequate treatment of GORD or other functional disorders. NICE advises that In some patients with an inadequate response to therapy or new emergent symptoms, it may become appropriate to refer to a specialist for a second opinion [2]. Once in secondary care a patient may undergo an endoscopy as a first step to confirming a diagnosis of GORD. In 40 to 60% of patients who undergo endoscopy off PPI drugs, there are no obvious signs of damage to the mucosa of the oesophagus, and they are diagnosed as having endoscopy negative reflux disease [4]. While on PPI drugs, a much higher proportion of patients will have no endoscopically detectable mucosal damage. The British Society of Gastroenterology states that Patients who continue to have heartburn or acid regurgitation despite a high dose proton pump inhibitor may benefit from ambulatory oesophageal ph monitoring [5]. This procedure involves placing either a wired catheter or a wireless probe with a ph sensor in the lower oesophagus to measure the acidity of any reflux over a period of hours. The measurements are recorded on a data storage system and the acidity of the oesophagus can be linked to the patient s symptoms. Intra-luminal oesophageal ph monitoring off medication is considered the gold standard for diagnosis of GORD, but there are limitations to this method as it does not allow assessment of non-acidic or gaseous reflux. The use of ph monitoring while on PPI drugs has not been validated to the same extent as monitoring while off PPI drugs, and normal criteria have yet to be formally defined. This may lead to patients with non-acid reflux being mistakenly given a diagnosis of other functional disorders. Oesophageal MII-pH devices Oesophageal MII-pH devices are an alternative to the existing oesophageal ph devices and have been considered by a panel of experts to be superior to oesophageal ph devices for the detection and categorisation of GORD [6]. Although similar in general appearance and size, oesophageal MII-pH devices include six or more impedance channels, between two electrodes, on the oesophageal catheter in addition to the ph sensor. The impedance channels measure electrical impedance, in ohms. The potential advantage of MII-pH over ph monitoring is the ability to determine if acid, non-acid or gaseous reflux are the cause of the patients symptoms and to differentiate between reflux and other functional disorders.

7 Introduction 7 When the catheter is placed within the oesophagus, the electrical impedance of the oesophageal mucosa is measured for each of the channels. Liquids either swallowed or refluxed from the stomach reduce the impedance when the gap between the two electrodes of a channel is bridged. The direction of the liquid transit can be found by the time delay between the drop in impedance at each successive channel. Reflux of a liquid causes a reduction in impedance at the lowest channel before moving up successive channels. The distance that the liquid reflux passes up the oesophagus is indicated by the number of channels that display a reduction in impedance. Gaseous reflux can be identified by an increase in impedance when one or more gas bubbles bridge the electrodes between each channel. The ph within the oesophagus is measured using a ph sensor. The normal ph of the oesophageal mucosa is approximately seven. A consensus report on reflux monitoring recommends that when the ph falls below four, this is considered an acidic reflux episode. If the ph falls more than one ph unit to between four and seven, then this is considered a weakly acidic reflux and if the ph rises above seven, then this is described as a weakly alkaline reflux episode [6]. The procedure for oesophageal MII-pH is similar to that for oesophageal ph monitoring. Investigations are usually undertaken on an outpatient basis for a period of 24 hours or potentially longer. The ph sensor on the catheter must be calibrated before each use and in addition the impedance channels quality checked to ensure the correct response in liquid. The catheter is inserted through the nose into a fasting patient. The ph sensor on the catheter is typically placed five centimetres above the upper border of the lower oesophageal sphincter (figure 2), although positioning requirements vary between catheters depending on design. The position of the lower oesophageal sphincter is usually found by manometry, a test which is also used to assess the motor activity of the oesophagus. The catheter is held in place by taping to the patient s nose and cheek. The catheter is connected to a data storage system and the patient is shown how to press certain buttons to indicate the occurrence of such events as eating, drinking, lying down, taking medication, or the onset of symptoms. The patient is also instructed to keep a paper diary to ensure all relevant information is captured. Figure 2. Location of the MII-pH catheter within the oesophagus

8 Introduction 8 After the investigation period the patient returns to the out-patient clinic and the catheter is removed. The measurements from the data recorder are downloaded onto a PC using the manufacturer s software. The paper diary and recordings are manually checked to ensure all relevant information has been recorded. Data can be reviewed by the operator and an electronic report issued, detailing the number and type of reflux episodes (acidic, weakly acidic, weakly alkaline or gaseous) and any association with the patient s symptoms. Normal values for the number and type of reflux episodes have been published for volunteers without GORD symptoms [7] and can be used as a standard to compare with the patient s results. Normal frequency and type of reflux may still be associated with the patient s symptoms. GORD can only be discounted as a cause of the patient s symptoms if there is no correlation between symptoms and reflux episodes. National guidance There is no reference to oesophageal MII-pH measurements in the NICE guidelines [2] as they are a relatively new technology and are unlikely to be used as a diagnostic tool in primary care. As with oesophageal ph measurements, the clinical application is likely to be in secondary care, mainly within the hospital setting. Scope While oesophageal MII-pH devices may have beneficial applications for oesophageal function testing [8], the purpose of this evidence review is to clarify the capability and appropriate diagnostic use of oesophageal MII-pH measurements in patients with persistent troublesome symptoms while receiving treatment for GORD.

9 Methods 9 Search strategy A systematic literature search was undertaken to identify published and un-published English language studies detailing the usefulness of either oesophageal MII-pH or ph measurements in relation to GORD. Sources Papers describing the use of oesophageal MII-pH and ph alone were identified using the databases Medline, EMBASE, CINAHL, Cochrane Reviews and Web of Science. Search terms The following search terms were employed for OvidSP to search MEDLINE and EMBASE. 1. exp Gastroesophageal Reflux/ 2. exp Esophageal ph Monitoring/ 3. exp Electric Impedance/ 4. (GORD or GERD).tw. 5. $esophageal reflux.tw. 6. persistent reflux.tw. 7. ambulatory ph.tw. 8. ((intraluminal or intra-luminal) and ph).tw. 9. ambulatory impedance.tw. 10. ((intraluminal or intra-luminal) and impedance).tw. 11. multichannel impedance.tw. 12. (ph and Impedance).tw. 13. ((intraluminal or intra-luminal) and impedance and ph).tw. 14. (ambulatory impedance and ph).tw. 15. (MII-pH or ph-mii).tw or 4 or 5 or or 7 or or 9 or 10 or 11 or 12 or 13 or 14 or and and 18

10 Methods or remove duplicates from limit 22 to (human and English language) The same search terms were employed for the other databases with slight changes to account for different database search conventions. No date restrictions other than those implememented by each database were applied to the search results. Inclusion criteria Only studies relating to adult patients over the age of 18 years were included for review. Apart from controls, all participants had a provisional diagnosis of GORD and their symptoms were not adequately controlled using either PPI drugs or other medication. Oesophageal MII-pH measurements either alone or compared with ph measurements within the same study were considered. Exclusion criteria Although there are published papers investigating the usefulness of MII-pH measurements in babies and young children, these were not included within the scope of this evidence review. Search results The search identified 2229 references, reduced to 298 after the removal of duplicates and clearly irrelevant articles. The criteria above were applied to the titles and abstracts to select the remaining 7 papers cited in this evidence review. Limitations of the review None of the articles cited in the evidence review are of meta-analysis or randomised controlled trial (RCT) design. Studies that are not meta-analysis or RCTs are open to bias and are considered lower quality evidence. The remaining studies are of multiple case study design and as such are of the lowest order in the evidence hierarchy. The studies cited in this evidence review are all peer reviewed original articles.

11 Evidence review 11 Diagnostic yield of MII-pH A number of studies [9-15] suggest that MII-pH can detect both acid and non-acid reflux. MII-pH also allows symptom association indices (SI) to be measured for all types of liquid reflux [9,11,12,14]. One of the potential advantages of MII-pH over ph alone is the detection of non-acid reflux. Between 37% and 39% of the patients undergoing MII-pH investigations had a positive symptom association for non-acid reflux [9,11,14]. For MII-pH testing the number of patients with a positive association between reflux and symptoms is higher than when using ph data alone [10]. Patients with no association between symptoms and reflux may potentially be identified more confidently using MII-pH than using ph monitoring [9,11,12,14]. Between 46% and 58% of patients on PPI treatment [11,12,14] and18% of patients not taking PPI [9] had no association between their symptoms and reflux events. MII-pH testing on or off medication Centres considering the introduction of MII-pH testing must decide whether to test patients while they are taking PPI medication, or when they are off medication. The majority of studies report MII-pH measurements while the patient continues to take medication. The total number of reflux events is similar for patients taking or not taking PPIs [10], but reflux appears to be predominantly non-acid for patients receiving PPI treatment [11,12,14] and acid for patients not receiving PPI treatment [9]. More patients were found to have a symptom association with reflux when tested off PPIs than on (50% versus 37%) [10]. One study [13] compares MII-pH measurements done on therapy and ph measurements off therapy. An abnormal MII-pH investigation based on the study criteria was associated with a 93% likelihood that the patient would have an abnormal ph study off therapy. Conversely, if the MII-pH investigation was normal, then this corresponded to a lower likelihood of an abnormal ph test. There is insufficient evidence to recommend whether testing should be performed while the patient is taking PPI medication or off medication. Training and interpretation Procedures for calibration, placement and removal of oesophageal MII-pH catheters are similar to those for ph catheters. The only exception is the additional quality check of the impedance channels to ensure they are all functioning correctly.

12 Evidence review 12 The interpretation of the results is more complex than for ph devices, but manufacturers supply software to aid interpretation. It is recommended that a manual assessment of the data is undertaken to ensure that there are no incorrectly assigned events caused by artefacts on the recording. The software will usually report one or more SIs to aid in the interpretation of the investigation. For each study, there are three possible outcomes - acid reflux,non-acid reflux, or no reflux that may be linked to patient symptoms. Due to the extra impedance data that need to be checked, reporting is more time consuming than for ph investigations. Reporting times for a ph study are typically of the order of 10 minutes, whilst a MII-pH study takes four times longer at around 40 minutes [16]. Workforce MII-pH measurements are likely to be carried out and reported by existing staff within the gastroenterology department and arrangements vary from hospital to hospital. In some departments, a gastrointestinal physiologist or a healthcare scientist undertakes the investigations. The individual should be appropriately trained, either by the supplier of MII-pH equipment or through secondment to another department. As the evidence base is weak, it is particularly important that procedures are in place for clinical audit. National guidelines recommend that clinicians undertaking oesophageal manometry and ambulatory oesophageal ph monitoring should be registered with the Association of Gastrointestinal Physiologists [5] and it would be prudent in the absence of specific guidance to apply this equally to those undertaking MII-pH measurements. Considering the four-fold increase in reporting times, extra staff may be required to change existing services from ph alone to MII-pH, especially in a busy department. Limitations of MII-pH One of the main limitations of MII-pH devices is the invasive nature of the catheters, as with conventional ph catheters. There is at least one catheterless ph sensor on the UK market that allows hour oesophageal ph monitoring [17]. Interventional procedure guidance issued by NICE supports the use of catheterless oesophageal ph monitoring [18] and cites evidence of reduced patient discomfort with the catheterless ph probe. In patients who cannot tolerate catheter based monitoring there could be a role for wireless monitoring. At present, there are no catheterless MII-pH devices on the market.

13 Evidence review 13 Table 1. Summary of published studies Reference Methods On/off therapy Results Limitations Kline et al, 2008 [9] MII-pH measurements in 37 GORD patients with persistent symptoms despite medication. All had previous negative endoscopy findings and a negative 24 hour ph test (defined as total ph<4 time <4.5%). MII-pH off therapy (medication stopped two weeks before) 16% had a retrospective positive standard ph test for acid reflux. 27% had positive symptom index (SI) for acid reflux. 38% had a positive SI for general reflux (acid, minor-acid and nonacid). 18% had no association between symptoms and reflux. Small study size. Not all patients on the same medication before the study. Original ph test did not have symptom association correlation. Hemmink et al, 2008 [10] Multicentre randomised cross-over study. 30 patients recruited with typical reflux symptoms despite PPI bid therapy twice a day. Random order of testing MII-pH on therapy MII-pH off therapy: medication stopped for between 1 4 weeks Classified reflux as acidic, nonacidic and weakly alkaline. On therapy: 37% had positive symptom association. Off therapy: 50% had positive symptom association. The addition of the impedance measurements increased the number of patients with a positive symptom association in 4 of the 16 patients on therapy and from 7 to 11 of those off therapy. Small number of participants Symptom association. frequency not statistically significant between measurements on or off therapy.

14 Evidence review 14 Reference Methods On/off therapy Results Limitations Sharma et al, 2008 [11] Retrospective review of 218 consecutive patients with persistent symptoms while on PPIs (twice daily) MII-pH on PPI therapy 18 patients non-symptomatic. Of the remaining symptomatic patients, 58% had a negative SI for all symptoms and 42% had positive SI for one or more symptom types. For patients with a positive SI, 83% were positive for non-acid reflux, 8% positive for acid reflux, and 8% positive for mixed acid and nonacid reflux. Retrospective study. Iwakiri et al, 2009 [12] 13 consecutive patients recruited with persistent symptoms despite taking PPIs (twice daily) MII-pH on PPI therapy 46% of patients had a negative SI for all symptoms. Acid reflux which was related to symptoms was 6.3%. Non-acid reflux which was related to symptoms was 55.7%. Very small number of participants. Exclusively Japanese patients. Double dose PPI equivalent to single dose PPI in UK.

15 Evidence review 15 Reference Methods On/off therapy Results Limitations Pritchett et al, 2009 [13] 39 patients recruited with persistent symptoms despite taking PPIs (twice daily) 24 hour MII-pH on PPI therapy 48 hour BRAVO Wireless ph monitoring off PPI therapy Off PPIs, 28% had normal acid exposure and 72% had abnormal exposure (%time ph>4 5.3%). On PPIs, 100% of patients had a normal acid exposure. Patients with abnormal impedance parameters (>48 reflux events) had significantly higher acid exposure off PPIs (93% vs 40%) than those with normal impedance parameters. Only the number reflux events were documented and no correlation with patient symptoms. Maine et al, 2006 [14] Multcentre study of 168 patients with persistent symptoms despite PPIs twice a day MII-pH on PPI therapy 14% of patients had no symptoms. 48% of patients had a positive SI and 52% had a negative SI. 23% of patients with a positive SI were for acid reflux. 77% of patients with a positive SI were for non-acid reflux.

16 Evidence review 16 Reference Methods On/off therapy Results Limitations Becker et al, 2007 [15] 143 patients recruited with persistent symptoms despite PPI therapy MII-pH on PPI therapy 40% of patients on PPIs had abnormal MII-pH investigation (based on >73 impedance detected reflux events or ph<4 for 4% time). Abnormal findings were found only on ph in six and only on impedance for 36. Patients that had an abnormal MIIpH investigation offered either surgery or escalation of PPIs. Of all patients who had the operation (4), 100% reported symptom relief. Of the patients where PPIs were escalated (33) 91% reported significant symptom relief. The symptom relief of the normal MII-pH patients with escalation of PPIs (30) was 42.4%. No randomisation Investigators not blinded to patient status

17 Economic issues 17 Economic issues There is no published economic analysis detailing the costs and benefits of using MII-pH devices. A full economic analysis is outside the scope of this report. Compared with ph devices, the costs of MII-pH devices are higher. Additional costs arise from increased staff time in interpretation of the results (estimated by one manufacturer to be of the order of four times higher). The results of published studies [9,11,14] indicate that 37-39% of patients undergoing MII-pH investigations (on therapy) had results suggesting non-acid reflux is the cause of their symptoms. In these patients continued PPIs and further medication or surgery may be required to bring their symptoms under control. There is also a significant sub-set of patients with suspected GORD whose symptoms are not associated with reflux [9,11,12,14]. The continued use of PPI drugs in patients whose symptoms are not reflux related is questionable and they are likely to need further investigation. Stopping PPI treatment for these patients could result in a considerable cost saving to the NHS, but this has to be considered in the context of the cost of further investigation and treatment of non-reflux symptomatic patients.

18 Conclusions 18 Conclusions MII-pH is a recent and emerging technology for diagnostic use in patients who have troublesome symptoms on treatment and has the potential to be used for other applications [8]. MII-pH devices incorporate ph measurement and may be regarded as a development of these devices, providing additional potentially useful diagnostic information. Experts in the field of GORD now consider MII-pH devices to be superior in the detection and categorisation of GORD compared with oesophageal ph devices [6]. At present, there are three suppliers of MII-pH devices in the UK (appendix 1). All manufacturers offer some form of training in the application of the devices and the interpretation of the results. Depending on the workload of the department, existing staffing levels may be sufficient, but there is an estimated four-fold increase in the reporting times of each investigation (10 minutes for ph alone versus 40 minutes for MII-pH) [16]. In a busy department this may necessitate the recruitment of additional staff. Although there is some evidence to support the use of MII-pH measurements, the quality of the studies is generally poor. Most of the studies do not have any case controls and there is variation between studies in the equipment and criteria used for assigning patients into different sub-groups. High quality studies are required to determine the optimum testing protocol, on or off therapy. Only one poor quality study discussed the outcome of changing patient management following MII-pH investigation [15]. At present the evidence is inconclusive for the use of MII-pH devices in patients with persistent symptoms while being treated for GORD.

19 Acknowledgements 19 We would like to thank the following for their contribution to this evidence review. Melanie Counter, Clinical Physiologist, University Hospital of Wales, Cardiff Robert Heading, Consultant Gastroenterologist, Association of GI Physiologists Gareth Thomas, Consultant Gastroenterologist, University Hospital of Wales, Cardiff Ardmore Healthcare Ltd. Sandhill Scientific UK Ltd. Synmed UK Ltd.

20 Glossary 20 Electrical impedance Endoscopy Heartburn Intra-luminal Lower oesophageal sphincter Manometry Oesophageal mucosa Oesophagus A measure of the opposition to the flow of current within a material A procedure for examining the internal body cavities by inserting a viewing instrument with a light source through a natural opening such as the nose or through a surgical opening. A painful burning sensation in the oesophagus. Within a tubular cavity. Muscular valve at the junction between the oesophagus and the stomach. A failure in the sphincter results in reflux of the stomach contents into the oesophagus. Test to assess the motor activity of the oesophagus and to locate the position of the lower oesophageal sphincter for catheter positioning. Inner surface of the oesophagus. The tube leading from the throat to the stomach. ph Symptom Index (SI) A scale representing the relative acidity of a solution. A value of seven is neutral, below seven is acidic and above seven is alkaline. ph is an abbreviation for potential hydrogen. A symptom association index. The number of symptoms associated with a reflux event divided by the total number of symptom episodes. The SI is usually considered positive if more than 50% of symptoms are associated with reflux within a short period of time.

21 References 21 [1] Dent J, El-Serag HB, Wallander MA, et al. Epidemiology of gastro-oesophageal reflux disease: a systematic review, Gut 2005;54: [2] National Institute for Health and Clinical Excellence. Management of dyspepsia in adults in primary care: Guidance Available at [3] Raguhunath AS, Hungin APS, Mason J, Jackson W. Symptoms in patients on long-term proton pump inhibitors: prevalence and predictors. Alimentary Pharmacology & Therapeutics 2009;29: [4] Armstrong D. Endoscopic Evaluation of Gastro-Esophageal Reflux Disease. Yale Journal of Biology and Medicine 1999;72: [5] Bodger K, Trudgill N. Guidelines for oesophageal manometry and ph monitoring, British Society of Gasteroenterology Available at [6] Sifrim D, Castell D, Dent J et al. Gastero-oesophageal reflux monitoring: review and consensus report on detection and definition of acid, non-acid, and Gas reflux. Gut 2004;53: [7] Shay S, Tutuian R, Sifrim D, Vela M, Wise S, Balaji N et al. Twenty Four hour ambulatory impedance-ph monitoring: review of normal volunteers. American Journal of Gastroenterology 2004;99: [8] Srinivasan R, Vela MF, Katz PO, Tutuian R, Castell JA, Castell DO. Esophageal function testing using multichannel intraluminal impedance. American Journal of Physiology Gastrointestinal and Liver Physiology 2001;280: [9] Kline MM, Ewing M, Simpson N, Laine L. The utility of intraluminal Impedance in Patients with Gastroesophageal Reflux Disease-Like symptoms But Normal Endoscopy and 24-Hour ph Testing. Clinical Gastroenterology and Hepatology 2008;6: [10] Hemmink GJM, Bredenoord AJ, Weusten BLAM, Monkelbaan JF, Timmer R, Smout AJPM. Esophageal ph-impedance Monitoring in Patients with Therapy- Resistant Reflux Symptoms: On or Off Proton Pump Inhibitor? American Journal of Gastroenterology 2008;103:

22 References 22 [11] Sharma N, Agrawal A, Freeman J, Vela MF, Castell D. An analysis of Persistent Symptoms in Acid-Suppressed Patients Undergoing Impedance-pH monitoring. Clinical Gastroenterology and Hepatology, 2008;6: [12] Iwakiri K, Kawami N, Sano H, Tanaka Y, Umezawa M, Kotoyori, M. et al. Acid and Non-acid reflux in Japanese patients with non-erosive reflux disease with persistent reflux symptoms, despite taking a double dose of proton pump inhibitor: a study using combined ph-impedance monitoring. Journal of Gastroenterology 2009;44: [13] Pritchett JM, Aslam M, Slaughter JC, Ness RM, Garrett CG, Vaezi M. Efficacy of Esophageal Impedance/pH Monitoring in Patients with Refractory Gastroesophageal Reflux Disease, on and off Therapy. Clinical Gastroenterology and Hepatology 2009;7: [14] Mainie I, Tutuian R, Shay S, Vela M, Zhang X, Sifrim D, et al. Acid and non-acid reflux in patients with persistent symptoms despite acid suppressive therapy: a mulitcentre study combined ambulatory impedance-ph monitoring. Gut 2006;55: [15] Becker V, Bajbouj M, Waller K., Schmid RM, Meining A. Clinical Trial: persistent gastro-oesophageal reflux symptoms despite standard therapy with proton pump inhibitors a follow up study of intraluminal-impedance guided therapy. Alimentary Pharmacology & Therapeutics 2007;26: [16] Ardmore Healthcare. correspondence. Received 01/02/2010 [17] Bravo wireless ph monitoring from Synectics Medical. Available at [18] National Institute for Health and Clinical Excellence. Catheterless oesophageal ph monitoring Available at

23 Appendix 1: Suplier contact details 23 Manufacturer Medical Measurement Systems Sandhill Scientific Inc Sierra Scientific Instruments Supplier Ardmore Healthcare Ltd Sandhill Scientific UK Ltd Synmed UK Ltd Address 25 South Road Amersham Bucks HP6 5LU Oakfield Industrial Estate Stanton Harcourt Road Eynsham Witney Oxon OX29 4AN SynMed House Unit 7, The Pavillions 6 Kinetic Crescent Innova Park Enfield EN3 7XH Telephone +44 (0) (+44) (0) (0) Fax +44 (0) (+44) (0) (0) Website

24 Author and report information 24 Evidence review: Oesophageal multichannel intraluminal impedance and ph measurement Matthew Talboys, Grace Carolan- Rees, Joelle Williams, Megan Dale, Andrew Cleves Clinical Engineering Device Assessment and Reporting (CEDAR) Cardiff Medicentre Cardiff CF14 4UJ Tel: Fax: mark FAO CEDAR For more information on CEDAR and our earlier reports visit About CEP The Centre for Evidence-based Purchasing (CEP) is part of the NHS Purchasing and Supply Agency. We underpin purchasing decisions by providing objective evidence to support the uptake of useful, safe and innovative products and related procedures in health and social care. CEP publications since 2002 are available from our website Crown Copyright 2010