Psychiatrist density and risk of suicide: a multilevel case-control study based on a national sample in Taiwan.

Aim: No previous studies, to our knowledge, have investigated the association between psychiatrist density and suicide, accounting for individual- and area-level characteristics.

Methods: We investigated all suicide cases in 2007-2017 identified from the national cause-of-death data files, with each suicide case matched to 10 controls by age and sex and each suicide case/control assigned to one of the 355 townships across Taiwan. Our primary outcome was the odds ratio (OR) of suicide and its 95% confidence interval (CI) estimated via multilevel models, which included both individual- and area-level characteristics. Townships with no psychiatrists were compared with the quartiles of townships with psychiatrists (density per 100,000 population): quartile 1 (Q1) (0.01-3.02); quartile 2 (Q2) (3.02-7.20); quartile 3 (Q3) (7.20-13.82); and quartile 4 (Q4) (>13.82).

Results: A total of 40,930 suicide cases and 409,300 age- and sex-matched controls were included. We found that increased psychiatrist density was associated with decreased suicide risk (Q1: adjusted OR [aOR], 0.95 [95% CI, 0.90-1.01]; Q2: aOR, 0.90 [95% CI, 0.85-0.96]; Q3: aOR, 0.89 [95% CI, 0.83-0.94]; Q4: aOR, 0.89 [95% CI, 0.83-0.95]) after adjusting for individual-level characteristics (employment state, monthly income, physical comorbidities, and the diagnosis of psychiatric disorders) and area socioeconomic characteristics.

Conclusions: The psychiatrist density-suicide association suggests an effect of increased availability of psychiatric services on preventing suicide. Suicide prevention strategies could usefully focus on enhancing local access to psychiatric services.