The association between living alone, loneliness and suicide mortality and effect modification by age: A case:control study

Background: Social isolation is a potentially reversible risk factor for suicide. Methods: A matched case control study design was used. The study population was from England and identified from an electronic primary case database with linkage to a secondary care database and Office for National Statistics mortality data. Cases were individuals who had been recorded as dying by suicide. Controls were randomly selected, matched by primary care centre and date of suicide mortality. Results: Data were available from 14,515 cases who died from suicide and 580,159 controls. After adjustment for age and sex, the risk of suicide in individuals who had previously been reported to be either living alone or suffering loneliness was increased (Odds ratio OR 4.9; 95 % confidence intervals CI: 4.4 to 5.5). Age affected the level of this risk, with individuals aged 15 to 34 years who were lonely or lived alone having a much higher risk of suicide (OR 16.4; 95 % CI: 8.7 to 31.1). Limitations: We can demonstrate an association between loneliness and living alone, but this may not be a causal effect. The conclusions may not be generalisable to societies outside the UK. Conclusions: Loneliness and social isolation are associated with an approximately five-fold increase in risk of mortality from suicide, which was substantially higher in younger adults. These represent potentially reversible risk factors for suicide mortality and may also help identify individuals who are at a higher risk of suicide.