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OBJECTIVES: Adequate relief (AR) of irritable bowel syndrome (IBS) symptoms (IBS-AR) has been used as a primary end point in many randomized controlled trials of IBS and is considered by the Rome III committee to be an acceptable primary end point. However, controversy exists on whether baseline severity confounds the effect of the treatment outcome. The aim (1) is to compare a subjective report of IBS-AR with global assessment of improvement (IBS-GAI), change in IBS symptom severity scale (IBS-SSS), and IBS quality of life (IBS-QOL); (2) to explore whether initial IBS symptom severity influences the ability of these outcome measures to detect differences post treatment; and (3) to determine whether psychological symptoms influence the sensitivity of these measures, in a randomized controlled treatment trial. METHODS: A total of 289 adult IBS patients were recruited to a treatment trial. Baseline IBS-SSS scores were used to classify IBS severity as mild (<175), moderate (175–300), or severe (>300). Questionnaires were completed at baseline and after 3 weeks of treatment with sham acupuncture or wait-list control. RESULTS: IBS baseline severity (IBS-SSS) significantly affected the proportion of patients who reported IBS-AR at 3 weeks (mild, 70%; moderate, 49.7%; severe, 38.8%) (P<0.05). However, once the patients who reported IBS-AR at baseline (28.0%) were excluded from the analysis, baseline severity no longer affected the proportion of patients reporting IBS-AR. Baseline severity did not have a significant effect on patients reporting moderate or significant improvement on the IBS-GAI (mild, 30%; moderate, 25.3%; severe, 18.8%) (P=NS). Psychological symptoms had no significant correlations with responders after adjusting for baseline severity. CONCLUSIONS: These data suggest that IBS-AR as an end point is inversely related to baseline symptom severity. However, if patients who report AR at screening were excluded from study participation, baseline symptom severity was no longer confounded with a report of AR at the study end point.
Objective To investigate whether placebo effects can experimentally be separated into the response to three components—assessment and observation, a therapeutic ritual (placebo treatment), and a supportive patient-practitioner relationship—and then progressively combined to produce incremental clinical improvement in patients with irritable bowel syndrome. To assess the relative magnitude of these components. Design A six week single blind three arm randomised controlled trial. Setting Academic medical centre. Participants 262 adults (76% women), mean (SD) age 39 (14), diagnosed by Rome II criteria for and with a score of ≥150 on the symptom severity scale. Interventions For three weeks either waiting list (observation), placebo acupuncture alone (“limited”), or placebo acupuncture with a patient-practitioner relationship augmented by warmth, attention, and confidence (“augmented”). At three weeks, half of the patients were randomly assigned to continue in their originally assigned group for an additional three weeks. Main outcome measures Global improvement scale (range 1-7), adequate relief of symptoms, symptom severity score, and quality of life. Results At three weeks, scores on the global improvement scale were 3.8 (SD 1.0) v 4.3 (SD 1.4) v 5.0 (SD 1.3) for waiting list versus “limited” versus “augmented,” respectively (P<0.001 for trend). The proportion of patients reporting adequate relief showed a similar pattern: 28% on waiting list, 44% in limited group, and 62% in augmented group (P<0.001 for trend). The same trend in response existed in symptom severity score (30 (63) v 42 (67) v 82 (89), P<0.001) and quality of life (3.6 (8.1) v 4.1 (9.4) v 9.3 (14.0), P<0.001). All pairwise comparisons between augmented and limited patient-practitioner relationship were significant: global improvement scale (P<0.001), adequate relief of symptoms (P<0.001), symptom severity score (P=0.007), quality of life (P=0.01).Results were similar at six week follow-up. Conclusion Factors contributing to the placebo effect can be progressively combined in a manner resembling a graded dose escalation of component parts. Non-specific effects can produce statistically and clinically significant outcomes and the patient-practitioner relationship is the most robust component. Trial registration Clinical Trials NCT00065403.
Little is known about placebo effects with scientific precision. Poor methodology has confounded our understanding of the magnitude and even the existence of the placebo effect. Investigating placebo effects presents special research challenges including: the design of appropriate controls for studying placebo effects including separating such effects from natural history and regression to the mean, the need for large sample sizes to capture expected small effects, and the need to understand such potential effects from a patient's perspective. This article summarizes the methodology of an ongoing NIH-funded randomized controlled trial aimed at investigating whether the placebo effect in irritable bowel syndrome (IBS) exists and whether the magnitude of such an effect can be manipulated to vary in a manner analogous to “dose dependence.” The trial also uses an innovative combination of quantitative and qualitative methods.
Patients in the placebo arms of randomized controlled trials (RCT) often experience positive changes from baseline. While multiple theories concerning such “placebo effects” exist, peculiarly, none has been informed by actual interviews of patients undergoing placebo treatment. Here, we report on a qualitative study (n = 27) embedded within a RCT (n = 262) in patients with irritable bowel syndrome. Besides identical placebo acupuncture treatment in the RCT, the qualitative study patients also received an additional set of interviews at the beginning, midpoint, and end of the trial. Interviews of the 12 qualitative subjects who underwent and completed placebo treatment were transcribed. We found that patients (1) were persistently concerned with whether they were receiving placebo or genuine treatment; (2) almost never endorsed “expectation” of improvement but spoke of “hope” instead and frequently reported despair; (3) almost all reported improvement ranging from dramatic psychosocial changes to unambiguous, progressive symptom improvement to tentative impressions of benefit; and (4) often worried whether their improvement was due to normal fluctuations or placebo effects. The placebo treatment was a problematic perturbation that provided an opportunity to reconstruct the experiences of the fluctuations of their illness and how it disrupted their everyday life. Immersion in this RCT was a co-mingling of enactment, embodiment and interpretation involving ritual performance and evocative symbols, shifts in bodily sensations, symptoms, mood, daily life behaviors, and social interactions, all accompanied by self-scrutiny and re-appraisal. The placebo effect involved a spectrum of factors and any single theory of placebo—e.g. expectancy, hope, conditioning, anxiety reduction, report bias, symbolic work, narrative and embodiment—provides an inadequate model to explain its salubrious benefits.
BACKGROUND: Despite the apparent high placebo response rate in randomized placebo-controlled trials (RCT) of patients with irritable bowel syndrome (IBS), little is known about the variability and predictors of this response. OBJECTIVES: To describe the magnitude of response in placebo arms of IBS clinical trials and to identify which factors predict the variability of the placebo response. METHODS: We performed a meta-analysis of published, English language, RCT with 20 or more IBS patients who were treated for at least 2 weeks. This analysis is limited to studies that assessed global response (improvement in overall symptoms). The variables considered as potential placebo modifiers were study design, study duration, use of a run-in phase, Jadad score, entry criteria, number of office visits, number of office visits/study duration, use of diagnostic testing, gender, age and type of medication studied. FINDINGS: Forty-five placebo-controlled RCTs met the inclusion criteria. The placebo response ranged from 16.0 to 71.4% with a population-weighted average of 40.2%, 95% CI (35.9-44.4). Significant associations with lower placebo response rates were fulfillment of the Rome criteria for study entry (P=0.049) and an increased number of office visits (P=0.026). CONCLUSIONS: Placebo effects in IBS clinical trials measuring a global outcome are highly variable. Entry criteria and number of office visits are significant predictors of the placebo response. More stringent entry criteria and an increased number of office visits appear to independently decrease the placebo response.
Abstract Background: Despite the apparent high placebo response rate in randomized placebo-controlled trials (RCT) of patients with irritable bowel syndrome (IBS), little is known about the variability and predictors of this response. Objectives: To describe the magnitude of response in placebo arms of IBS clinical trials and to identify which factors predict the variability of the placebo response. Methods: We performed a meta-analysis of published, English language, RCT with 20 or more IBS patients who were treated for at least 2 weeks. This analysis is limited to studies that assessed global response (improvement in overall symptoms). The variables considered as potential placebo modifiers were study design, study duration, use of a run-in phase, Jadad score, entry criteria, number of office visits, number of office visits/study duration, use of diagnostic testing, gender, age and type of medication studied. Findings: Forty-five placebo-controlled RCTs met the inclusion criteria. The placebo response ranged from 16.0 to 71.4% with a population-weighted average of 40.2%, 95% CI (35.9–44.4). Significant associations with lower placebo response rates were fulfilment of the Rome criteria for study entry (P = 0.049) and an increased number of office visits (P = 0.026). Conclusions: Placebo effects in IBS clinical trials measuring a global outcome are highly variable. Entry criteria and number of office visits are significant predictors of the placebo response. More stringent entry criteria and an increased number of office visits appear to independently decrease the placebo response.
OBJECTIVES: This study aimed to compare the effects of true and sham acupuncture in relieving symptoms of irritable bowel syndrome (IBS). METHODS: A total of 230 adult IBS patients (75% females, average age: 38.4 years) were randomly assigned to 3 weeks of true or sham acupuncture (6 treatments) after a 3-week "run-in" with sham acupuncture in an "augmented" or "limited" patient–practitioner interaction. A third arm of the study included a waitlist control group. The primary outcome was the IBS Global Improvement Scale (IBS-GIS) (range: 1–7); secondary outcomes included the IBS Symptom Severity Scale (IBS-SSS), the IBS Adequate Relief (IBS-AR), and the IBS Quality of Life (IBS-QOL). RESULTS: Although there was no statistically significant difference between acupuncture and sham acupuncture on the IBS-GIS (41 vs. 32%, P=0.25), both groups improved significantly compared with the waitlist control group (37 vs. 4%, P=0.001). Similarly, small differences that were not statistically significant favored acupuncture over the other three outcomes: IBS-AR (59 vs. 57%, P=0.83), IBS-SSS (31 vs. 21%, P=0.18), and IBS-QOL (17 vs. 13%, P=0.56). Eliminating responders during the run-in period did not substantively change the results. Side effects were generally mild and only slightly greater in the acupuncture group. CONCLUSIONS: This study did not find evidence to support the superiority of acupuncture compared with sham acupuncture in the treatment of IBS.