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Treatment of irritable bowel syndrome: a review of randomised controlled trials |
Akehurst R, Kaltenthaler E |
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Authors' objectives To review and assess published randomised controlled trials (RCTs) examining the clinical effectiveness of interventions for irritable bowel syndrome (IBS) treatments.
Searching The Cochrane Library, DARE, MEDLINE and EMBASE were searched (search dates unclear) using the keywords 'colonic diseases', 'functional' and 'clinical trials'. General reviews, meta-analyses and references from published RCTs were also used. Trials published in peer-reviewed journals between 1987 and 1998, in either English, French, German, Italian or Spanish, were included.
Study selection Study designs of evaluations included in the reviewRCTs. Both placebo-controlled trials and trials that compared different treatments were eligible for inclusion. Studies that were not clearly randomised were excluded.
Specific interventions included in the reviewThe interventions included bulking agents, anticholinergics/antispasmodics, antidiarrhoeals, prokinetic drugs, antidepressants/psychotropic drugs, serotonergic antagonist drugs, combinations of drugs, and recent or miscellaneous drugs. Trials with a high-fibre diet or a fibre supplementation taken in all groups were also included. Drugs with only a pharmacological effect on motility were excluded.
Participants included in the reviewPatients with IBS. No further details of the participants were reported.
Outcomes assessed in the reviewA range of outcome measures were reported including the following: nausea, vomiting, abdominal pain, bowel habit, distension, overall symptom scores, depression, well-being and pain relief.
How were decisions on the relevance of primary studies made?The authors do not state how the papers were selected for the review, or how many of the reviewers performed the selection.
Assessment of study quality The studies were assessed according to the criteria of Jadad et al. (see Other Publications of Related Interest). The RCTs were assessed for sample size, number of drop-outs, blinding, intervention and outcomes. The authors do not state how many of the reviewers performed the validity assessment.
Only studies of adequate quality were included in the synthesis. These studies used an appropriate method of randomisation, were double-blind, and described withdrawals and drop-outs.
Data extraction The authors do not state how the data were extracted for the review, or how many of the reviewers performed the data extraction.
Data were extracted for the following categories: author and year; treatments compared; diagnostic criteria; study design; number of patients entered into the trial; number of drop-outs; treatment period; outcome measures; and results.
Methods of synthesis How were the studies combined?A narrative synthesis was undertaken.
How were differences between studies investigated?Differences between the studies were discussed, and the results were grouped according to intervention type.
Results of the review Forty-five RCTs met the inclusion criteria, of which only 6 studies were of adequate quality and were reported.
Bulking agents (2 RCTs).
There was some evidence that bulking agents may be effective in treating constipation associated with IBS, although there is little reason to believe that they are effective for the entire IBS symptom complex.
Antispasmodics/anticholinergic drugs (2 RCTs).
Two studies compared cimetropium bromide with placebo. In the first, whole gut transit time was significantly shortened in the cimetropium group (p<0.01), and the global clinical condition was improved(p=0.029). The second study found a significant reduction in pain and the number of pain episodes (p<0.01). Compared with the placebo group, a greater proportion of those receiving cimetropium considered themselves to be globally improved (p=0.039).
Antidepressant/psychotropic drugs (2 RCTs).
One study compared amineptine with placebo in patients who scored at least 15 out of 24 on the Hamilton depression scale. Amineptine produced a significantly greater improvement in the Hamilton score than the placebo did. Amineptine was also more effective in treating depressed mood, retardation and cognitive dysfunction. The second study looked at a combination of buzepide metiodide and haloperidol. This found an improvement in the frequency of symptoms and intensity of the most frequent symptoms, abdominal pain and distension, compared with placebo. Patients also reported a greater global improvement than the placebo group.
Authors' conclusions The literature review of treatments for IBS identified few RCTs, and the research overall was of poor quality. The majority of the published trials failed to meet even simple criteria for acceptability. Despite this, a variety of interventions were shown to be clinically effective in the treatment of symptoms of IBS, although no drug was effective in treating all the symptoms. A variety of outcome measures were used, thus making it difficult to compare the results of trials.
CRD commentary This was a poor review of the area. The literature search was limited, and the review was restricted to those studies published in peer-reviewed journals. The results may, therefore, be subject to publication bias. Very few details of the review process were described. The authors failed to report how many authors were involved in the various review processes, i.e. assessing the studies for inclusion, data extraction and quality assessment. An appropriate quality assessment was performed and adequate study details were tabulated. A narrative synthesis was appropriate given the heterogeneity of the studies in terms of the interventions and outcomes.
The main limitation of this review was that only the results of studies of very high quality (adequate randomisation, double-blind with description of withdrawals and drop-outs) were discussed. This reduced the number of included studies from 45 to 6. The results of the other studies were tabulated, but these were not synthesised in any way. Given the wide variety of interventions used to treat IBS and the nature of this condition, the inclusion of only 6 trials does not provide much information on the effectiveness of the various treatments for IBS. The review would have been considerably more informative had the results of all 45 studies been discussed. These were all randomised trials, and the majority were double-blinded with a description of the drop-outs. Most were excluded from the review because they did not provide a description of the randomisation process.
The conclusions were not supported by the results presented, and should be interpreted with caution due to the limitations highlighted.
Implications of the review for practice and research Practice: No recommendations for clinical practice can be made because of the poor quality of this review.
Research: The authors state that 'it is essential that RCTs are conducted of consistently identified patients with clearly defined outcome measures. These outcome measures should not only deal with symptom relief but also improvement in quality of life and associated measures such as time off work'.
Bibliographic details Akehurst R, Kaltenthaler E. Treatment of irritable bowel syndrome: a review of randomised controlled trials. Gut 2001; 48(2): 272-282 Other publications of related interest Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJ, Gavaghan DJ, et al. Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 1996;17:1-12.
Indexing Status Subject indexing assigned by NLM MeSH Colonic Diseases, Functional /therapy; Double-Blind Method; Gastrointestinal Agents /therapeutic use; Humans; Psychotropic Drugs /therapeutic use; Randomized Controlled Trials as Topic; Research Design /standards; Treatment Outcome AccessionNumber 12001000437 Date bibliographic record published 30/06/2002 Date abstract record published 30/06/2002 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
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