Background Both the rates of self-reported mental ill-health and the number of individuals in receipt of psychotropic medications are increasing across the UK. Research suggests that poor mental health is a major predictor of death by suicide, but measuring individual level mental ill-health can be difficult. Population-wide prescription medication records are available in many countries and could provide useful information on indicators of suicide risk, however, the association between self-reported mental health, medication record and suicide has not been well explored. This study aimed to assess if self-reported mental health, psychotropic medication record, or both in combination better predict risk of death by suicide.

Methods Data from the 2011 Northern Ireland Census on all individuals living in the community aged 18–74 years (n=1,098,967) were linked to the Enhanced Prescribing Database (EPD) and death registrations and followed up until end of 2015. Mental health status was ascertained through a single-item self-reported mental health question from the Census and/or a record of psychotropic medication in the EPD. Deaths by suicide were identified using ICD-10 codes. Logistic regression models were used to examine the association between measures of mental health and death by suicide, with adjustment for census-based individual attributes known to be associated with mental ill-health and suicide.

Results A total of 857 out of the 1,098,967 individuals died by suicide during the study period. The proportion who died by suicide was 0.05% in those without mental ill-health, 0.21% in those who self-reported poor mental health, 0.16% in those in receipt of psychotropic medication, and 0.38% in those with both self-report and psychotropic medication record. In the unadjusted logistic regression model, having both self-report and psychotropic medication record was the strongest predictor of suicide (OR=8.23, 95%CI: 6.97–9.72). Upon adjustment for sociodemographic characteristics and physical health morbidities, having both self-report and psychotropic medication record remained the strongest suicide predictor (OR=6.13, 95%CI: 4.94–7.61), followed by psychotropic medication record only (OR=4.00, 95%CI: 3.28–4.88) and self-report only (OR=2.88, 95%CI: 2.16–3.84).

Conclusion Individuals with both self-reported poor mental health and receipt of psychotropic medication had the highest likelihood of death by suicide. Of the two measures individually, receipt of psychotropic medication was associated with a higher likelihood of suicide mortality compared to self-reported mental health. Understanding which measures are the best indicators of suicide risk is vitally important for the effective targeting of interventions.