What are the sociodemographic and gender determinants of non-fatal self-harm in older adult users and non-users of antidepressants? A national population-based study.

Background: Late-life self-harm (SH) is often linked to depression. However, very few studies have explored the role of other factors and their interaction with depression in the occurrence of late-life SH. The objective of this research was to examine sociodemographic and gender factors associated with non-fatal SH, in older adults with and without antidepressant therapy.

Methods: We used national longitudinal register data from a total cohort of all Swedish residents aged ≥75 years between 2006 and 2014 (N = 1,413,806). Using personal identity numbers, we linked individuals' data from numerous national registers. We identified all those with at least one episode of non-fatal self-harm (regardless of level of intent to die) and matched 50 controls to each case. A nested case-control design was used to investigate sociodemographic factors associated with non-fatal SH in the total cohort and among antidepressant users and non-users. Risk factors were analysed in adjusted conditional logistic regression models for the entire cohort and by gender.

Results: In all, 2242 individuals had at least one episode of a non-fatal SH (980 men and 1262 women). Being unmarried was a risk factor for non-fatal SH in men but not in women. Among users of antidepressants, higher non-fatal SH risk was observed in those born outside the Nordic countries (IRR: 1.44; 95% CI: 1.11-1.86), whereas in AD non-users increased risk was seen in those from Nordic countries other than Sweden (IRR: 1.58; 95% CI: 1.08-2.29). Antidepressant users with higher education had an increased risk of non-fatal SH (IRR: 1.34; 95% CI: 1.12-1.61), in both men and women.

Conclusions: Foreign country of birth was associated with increased risk for non-fatal SH in older adults with and without AD therapies. Being married was a protective factor for non-fatal SH in men. The complex association between sociodemographic factors and use of antidepressants in the occurrence of self-harm in older men and women indicates the need for multifaceted tailored preventive strategies including healthcare and social services alike.