Background This study investigates the degree to which a previous hospitalisation for injury of any intent is a risk of subsequent youth suicide and whether this association is influenced by family socioeconomic status or economic stress.

Methods A nationwide register-based cohort study was conducted covering all Swedish subjects born between January 1977 and December 1991 (N=1 616 342, male/female ratio=1.05). The cohort subjects were followed-up from January 1998 to December 2003, when aged 7–26 years. Poisson regression and the likelihood ratio test (95% CI) were used to assess the age-adjusted effect of hospitalisation for injuries of various intent on youth suicide and its effect once adjusted for family sociodemographic and social circumstances.

Results Each set of exposures was associated independently and significantly with suicide mortality. Being hospitalised for self-inflicted injuries or injuries of undetermined intent was associated with a risk of suicide 36 to 47 times, respectively, that of subjects never hospitalised in the period under study (95% CI 28.36 to 45.58 and 26.67 to 83.87 for self-inflicted injuries and for events of undetermined intent, respectively; overall p<0.01). Similarly, previous events of unintentional injury markedly increased the risk of suicide (RR 3.08; 95% CI 2.26 to 4.19). These effects were solid and not substantially altered after adjustment for family demographic and socioeconomic circumstances.

Conclusion A strong association exists between previous hospitalisation for injury of any intent and youth suicide. The association is robust and unaltered by family socioeconomic circumstances.