Placebo Group Improvement in Trials of Pharmacotherapies for Alcohol Use Disorders: A Multivariate Meta-Analysis Examining Change Over Time

• Published in: Journal of clinical psychopharmacology Vol. 33; no. 5; pp. 649 - 657
• Main Authors: DEL RE, A. C, MAISEL, Natalya, BLODGETT, Janet C, WILBOURNE, Paula, FINNEY, John W
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01-10-2013
• Subjects: Addictive behaviors; Adult and adolescent clinical studies; Alcohol-Related Disorders - diagnosis; Alcohol-Related Disorders - drug therapy; Alcoholism; Alcoholism and acute alcohol poisoning; Biological and medical sciences; Controlled Clinical Trials as Topic - methods; Controlled Clinical Trials as Topic - trends; Humans; Medical sciences; Multivariate Analysis; Neuropharmacology; Pharmacology. Drug treatments; Placebo Effect; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Research Design - trends; Severity of Illness Index; Time Factors; Toxicology; Treatment Outcome; Human; Alcoholic beverage; Treatment; Social group; Alcoholism; Ingroup; Placebo; Pharmacotherapy; Substance abuse; Review; Multivariate analysis; Metaanalysis
• ISSN: 0271-0749; 1533-712X
• DOI: 10.1097/JCP.0b013e3182983e73

Placebo group improvement in pharmacotherapy trials has been increasing over time across several pharmacological treatment areas. However, it is unknown to what degree increasing improvement has occurred in pharmacotherapy trials for alcohol use disorders or what factors may account for placebo group improvement. This meta-analysis of 47 alcohol pharmacotherapy trials evaluated (1) the magnitude of placebo group improvement, (2) the extent to which placebo group improvement has been increasing over time, and (3) several potential moderators that might account for variation in placebo group improvement.
Random-effects univariate and multivariate analyses were conducted that examined the magnitude of placebo group improvement in the 47 studies and several potential moderators of improvement: (a) publication year, (b) country in which the study was conducted, (c) outcome data source/type, (d) number of placebo administrations, (e) overall severity of study participants, and (f) additional psychosocial treatment.
Substantial placebo group improvement was found overall and improvement was larger in more recent studies. Greater improvement was found on moderately subjective outcomes, with more frequent administrations of the placebo, and in studies with greater participant severity of illness. However, even after controlling for these moderators, placebo group improvement remained significant, as did placebo group improvement over time.
Similar to previous pharmacotherapy placebo research, substantial pretest to posttest placebo group improvement has occurred in alcohol pharmacotherapy trials, an effect that has been increasing over time. However, several plausible moderator variables were not able to explain why placebo group improvement has been increasing over time.