Background: The American Cancer Society's Cancer Prevention Study II was a large survey designed primarily to examine cancer risks such as cigarette smoking. From the same survey and methods, data on usage of "prescription sleeping pills" in 1982 were examined.
Methods: Standardized mortality ratios were computed. Because sleeping pill use could be a proxy for other risk factors, cox proportional hazards models were computed to control for possible confounding factors as extensively as the data permitted.
Results: Men and women who reported taking prescription sleeping pills 30+ times in the past month had standardized mortality ratios of 3.18 and 2.82, respectively; controlling for 10-year age groups (p < 0.001). The standardized mortality ratios for usage 1-29 times/month were 1.8 and 1.48, respectively (p < 0.001). In proportional hazards models that controlled for 30 other risk factors and comorbidities simultaneously, the excess mortality risk associated with usage 30+ times per month remained significant, but hazard ratios were reduced to 1.35 for men and 1.22 for women.
Conclusions: Use of hypnotics was associated with excess mortality. This methodology could not determine if hypnotic compounds caused the risks associated with their use, nor could the risks of individual compounds be determined. Since millions of Americans are currently taking hypnotics, long-term controlled trials are urgently needed to further guide both patients and physicians.