Suicide in prisons: an international study of prevalence and contributory factors

BACKGROUND: Prison suicide rates, rate ratios, and associations with prison-related factors need clarification and updating. We examined prison suicide rates in countries where reliable information was available, associations with a range of prison-service and health-service related factors, how these rates compared with the general population, and changes over the past decade. METHODS: We collected data for prison suicides in 24 high-income countries in Europe, Australasia, and North America from their prison administrations for 2011-14 to calculate suicide rates and rate ratios compared with the general population. We used meta-regression to test associations with general population suicide rates, incarceration rates, and prison-related factors (overcrowding, ratio of prisoners to prison officers or health-care staff or education staff, daily spend, turnover, and imprisonment duration). We also examined temporal trends. FINDINGS: 3906 prison suicides occurred during 2011-14 in the 24 high-income countries we studied. Where there was breakdown by sex (n=2810), 2607 (93%) were in men and 203 (7%) were in women. Nordic countries had the highest prison suicide rates of more than 100 suicides per 100 000 prisoners apart from Denmark (where it was 91 per 100 000), followed by western Europe where prison suicide rates in France and Belgium were more than 100 per 100 000 prisoners. Australasian and North American countries had rates ranging from 23 to 67 suicides per 100 000 prisoners. Rate ratios, or rates compared with those in the general population of the same sex and similar age, were typically higher than 3 in men and 9 in women. Higher incarceration rates were associated with lower prison suicide rates (b = -0·504, p = 0·014), which was attenuated when adjusting for prison-level variables. There were no associations between rates of prison suicide and general population suicide, any other tested prison-related factors, or differing criteria for defining suicide deaths. Changes in prison suicide rates over the past decade vary widely between countries. INTERPRETATION: Many countries in northern and western Europe have prison suicide rates of more than 100 per 100 000 prisoners per year. Individual-level information about prisoner health is required to understand the substantial variations reported and changes over time. FUNDING: Wellcome Trust and the UK National Institute for Health Research (NIHR).