Associations of treatment with hypnotics with suicide and attempted suicide: A nationwide cohort study.

Background: Hypnotics have been linked to suicidal behaviors. While existing evidence has established findings of associations, more knowledge is needed regarding benzodiazepine (BZD) and non-benzodiazepine (n-BZD) hypnotics.

Aim: To examine whether individuals in treatment with hypnotics had higher rates of suicide and suicide attempts than those not in treatment.

Methods: A longitudinal nationwide cohort design was applied to individual-level register data, including all individuals aged 15+ years who lived in Denmark from 1995 to 2021. Incidence rate ratios (IRR) for suicide and suicide attempts were estimated using Poisson regression models. Using the National Prescription Registry, individuals who redeemed prescriptions for hypnotics at pharmacies were identified. Death by suicide was identified in the Cause of Death Register.

Results: A total of 7,311,630 individuals were observed over 122,681,369 person-years. In all, 678 males and 553 females died by suicide while in treatment with BZD, resulting in respective adjusted IRRs of 2.1 (95% CI: 1.9-2.4) and 2.6 (95% CI: 2.3-3.0), when compared to those not in treatment. A total of 1774 males and 1212 females died by suicide while in treatment with n-BZD and the adjusted IRRs were 3.4 (95% CI: 3.1-3.7) and 3.6 (95% CI: 3.4-3.9), respectively.

Conclusions: While confounding by indication is likely to be a major contributor, the fact that individuals in treatment with BZD or n-BZDs had higher rates of suicide and suicide attempts when compared to those not in treatment emphasizes the need to carefully monitor their mental state.