Effect of anxiolytic and hypnotic drug prescriptions on mortality hazards: retrospective cohort study

摘要

The main reason for caution is confounding by indication—study drugs may be given more often to those who are seriously ill. This was explored in the main analysis by controlling for a large number of physical and psychiatric morbidities as well as prescriptions of other drugs, and in subgroup analysis restricted to people who survived the first year (when confounding is more probable). These procedures resulted in appropriately conservative estimates, but still showed increased mortality in those prescribed study drugs. There also remains potential for residual confounding by unmeasured or incompletely measured factors, such as socioeconomic status and disease severity. These results add to evidence of an association with mortality, but must be treated with caution.