Gambling-related harm is a global public health concern. Suicide mortality is increased among people who experience gambling harm, and people who die by suicide often have contact with mental health treatment services in the months preceding their death.

To assess via a case–control study how gambling diagnosis predicts suicidal death and mental healthcare utilisation using linked routinely collected healthcare data.

We linked the Welsh Longitudinal General Practice Dataset, Annual District Death Extract, Patient Episode Database for Wales, and Outpatient Appointments Dataset Wales using the Secure Anonymised Information Linkage (SAIL) Databank. A sample of individuals with gambling diagnosis who died by suicide and an age- and sex-matched comparator group of all-cause decedents between 1993 and 2023 were extracted. Predictors of suicidal death, including mental health diagnosis and treatment contacts, were analysed using binary logistic regression models and chi-squared tests.

A matched cohort of 92 individuals diagnosed with a gambling diagnosis (mean age 61.5 years, s.d. 13.1; 71% male) who died by suicide and 2990 comparators were identified. Gambling diagnosis status was a significant predictor of suicide (odds ratio 30.94; 95% CI 3.57–268.28; P = 0.002). Individuals with gambling disorder had significantly more mental health treatment contacts (P < 0.001), particularly in-patient contacts (P < 0.001). No difference in out-patient contacts was found.

Historical diagnosis of gambling harm is a significant predictor of suicidal death and mental health treatment utilisation. Improved screening and coding practices would facilitate greater data linkage research on gambling-related suicide and suicide prevention.