Benzodiazepines and zolpidem for chronic insomnia: a meta-analysis of treatment efficacy.

OBJECTIVE To evaluate the efficacy of benzodiazepines and zolpidem tartrate in chronic insomnia based on a quantitative review of literature. DATA SOURCES Articles from 1966 to 1996 were identified using MEDLINE, by a manual review of relevant journals, and from bibliographies of identified articles. STUDY SELECTION Studies using randomized, double-blind, placebo-controlled, parallel or crossover designs with benzodiazepines or zolpidem in adults younger than 65 years with chronic insomnia (modified Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for primary insomnia) were selected for review. Self-report and polysomnographic measures of sleep-onset latency, total sleep time, number of awakenings, and sleep quality were selected as outcomes. DATA EXTRACTION Twenty-two studies met the selection criteria. A combined test of Pvalues was performed, pooling broadly from the 22 studies to determine whether medication was superior to placebo. A combined test of effect sizes was performed on the subset of studies that reported effect size information to determine the magnitude of medication effect. DATA SYNTHESIS A homogeneous sample of studies summarized 1894 patients treated for a median duration of 7 days. The combined test of P values demonstrated that medication was superior to placebo in all 4 outcome measures. Treatment response was moderate in magnitude by the combined test of effect sizes. CONCLUSIONS Benzodiazepines and zolpidem produced reliable improvements in commonly measured parameters of sleep in patients with chronic insomnia. Relative to the chronic and recurring course of insomnia, both the limited duration of treatments studied and the lack of follow-up data from controlled trials represent challenges for developing evidence-based guidelines for the use of hypnotics in the management of chronic insomnia.