Patient and practitioner influences on the placebo effect in irritable bowel syndrome.
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 patients with irritable bowel syndrome who were 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 relationships between the placebo response and a) patient personality and demographics; b) treating practitioner; and c) the patient-practitioner interaction as captured on videotape and rated by the Psychotherapy Process Q-Set.


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; 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
Personality and gender influenced the 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 the placebo response. 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.
Kelley
John M
JM
Psychology Department, Endicott College, 376 Hale Street, Beverly, MA 01915, USA. JohnKelley@Post.Harvard.Edu
Lembo
Anthony J
AJ
Ablon
J Stuart
JS
Villanueva
Joel J
JJ
Conboy
Lisa A
LA
Levy
Ray
R
Marci
Carl D
CD
Kerr
Catherine E
CE
Kirsch
Irving
I
Jacobson
Eric E
EE
Riess
Helen
H
Kaptchuk
Ted J
TJ
D015670:Acupuncture Therapy; D000328:Adult; D000368:Aged; D005120:Extraversion, Psychological; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000523:psychology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D010555:Personality Inventory / Q000706:statistics & numerical data; D010817:Physician-Patient Relations; D015990:Placebo Effect; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data; D012044:Regression Analysis; D017678:Sex Distribution; D016896:Treatment Outcome; D014741:Video Recording; D014850:Waiting Lists