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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.
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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.
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Objective
To determine whether placebo responses can be explained by characteristics of the patient, the practitioner, or their interpersonal interaction.
Methods
We performed an analysis of videotape and psychometric data from a clinical trial of IBS patients treated with placebo acupuncture in either a warm empathic interaction (Augmented, n=96), a neutral interaction (Limited, n=97), or a waitlist control (Waitlist, n=96). We examined the relations between placebo response and: (1) patient personality and demographics; (2) treating practitioner; and (3) the patient-practitioner interaction as captured on videotape and rated by the Psychotherapy Process Q-Set (PQS).
Results
Patient extraversion, agreeableness, openness to experience, and female gender were associated with placebo response, but these effects held only in the augmented group. Regression analyses controlling for all other independent variables suggest that only extraversion is an independent predictor of placebo response. There were significant differences between practitioners in outcomes, and this effect was twice as large as the effect attributable to treatment group assignment. Videotape analysis indicated that the augmented group fostered a treatment relationship similar to a prototype of an ideal healthcare interaction.
Conclusions
Gender and personality influenced placebo response, but only in the warm, empathic, augmented group. This suggests that to the degree a placebo effect is evoked by the patient-practitioner relationship, personality characteristics of the patient will be associated with placebo response. This finding may explain why consistent predictors of the placebo response have been difficult to detect. In addition, practitioners differed markedly in effectiveness, despite standardized interactions. We propose that the quality of the patient-practitioner interaction accounts for the significant difference between the groups in placebo response.
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Objective To investigate whether a sham device (a validated sham acupuncture needle) has a greater placebo effect than an inert pill in patients with persistent arm pain.
Design A single blind randomised controlled trial created from the two week placebo run-in periods for two nested trials that compared acupuncture and amitriptyline with their respective placebo controls. Comparison of participants who remained on placebo continued beyond the run-in period to the end of the study.
Setting Academic medical centre.
Participants 270 adults with arm pain due to repetitive use that had lasted at least three months despite treatment and who scored ≥3 on a 10 point pain scale.
Interventions Acupuncture with sham device twice a week for six weeks or placebo pill once a day for eight weeks.
Main outcomemeasures Arm pain measured on a 10 point pain scale. Secondary outcomes were symptoms measured by the Levine symptom severity scale, function measured by Pransky's upper extremity function scale, and grip strength.
Results Pain decreased during the two week placebo run-in period in both the sham device and placebo pill groups, but changes were not different between the groups (−0.14, 95% confidence interval −0.52 to 0.25, P = 0.49). Changes in severity scores for arm symptoms and grip strength were similar between groups, but arm function improved more in the placebo pill group (2.0, 0.06 to 3.92, P = 0.04). Longitudinal regression analyses that followed participants throughout the treatment period showed significantly greater downward slopes per week on the 10 point arm pain scale in the sham device group than in the placebo pill group (−0.33 (−0.40 to −0.26) v −0.15 (−0.21 to −0.09), P = 0.0001) and on the symptom severity scale (−0.07 (−0.09 to −0.05) v −0.05 (−0.06 to −0.03), P = 0.02). Differences were not significant, however, on the function scale or for grip strength. Reported adverse effects were different in the two groups.
Conclusions The sham device had greater effects than the placebo pill on self reported pain and severity of symptoms over the entire course of treatment but not during the two week placebo run in. Placebo effects seem to be malleable and depend on the behaviours embedded in medical rituals.
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