0342 A META-ANALYSIS OF PLACEBO EFFECTS ACROSS HYPNOTIC RCTS: A FIRST PASS ANALYSIS

Abstract

Introduction: While there have been at least three meta-analyses on the subject of placebo effects in insomnia and several theory papers addressing the factors that may account for such effects, little is known about the relative magnitude of placebo effects on sleep continuity as assessed both objectively (PSG) and subjectively (Sleep Diaries). The prior studies notwithoutstanding, it is generally assumed that placebo effects disproportionately affect self-report outcomes. In order to address this issue, placebo effects (in terms of pre-post treatment outcome) were independently evaluated as part of a larger meta-analytic study on the relative efficacy of pharmacologic treatments for insomnia. Method(s): PubMed searches, 1967-June 2016, yielded 327 possible articles of RCTs evaluating BZs, BZRAs, SADs, DORAs, or melatonin agonists [MELA]). Of these investigations, 30 studies met the inclusion and exclusion criteria for the present sub-analysis. Average change, average percent change and weighted effect sizes (ES) were computed for SL, WASO and TST from the studies that provided data on acute treatment (studies that were between 1 and 14 days in duration). Result(s): Pre-to-post change on PSG measures across all medication studies were as follows: SL (-19.2 min. -29.8%, ES=0.43); WASO (-16.9 min, 15.7%, ES=0.35); and TST (36.1 min, 11.1%, ES=0.62). Pre-to-post change on Sleep Diary measures across all medication studies were as follows: SL (-19.5 min, -23.8%, ES=0.28); WASO (-12 min, -13%, ES=0.55); and TST (37 min, -10.5 %, ES=0.42). Conclusion(s): The acute effects of placebo administration corresponded to between 10% and 30% pre-to-post change in the various sleep continuity measures with corresponding effect sizes of between 0.28 and 0.62. The overall average ESs for PSG measures and Sleep Diaries appeared to be comparable (PSG=0.47 vs. SD=0.42), although the ESs for PSG measures on SL and TST were larger than the corresponding Sleep Diary measures.