Determinants of long-term unplanned readmission and mortality following self-inflicted and non-self-inflicted major injury: a retrospective cohort study

To describe the characteristics of major injury and identify determinants of long-term unplanned readmission and mortality after self-inflicted and non-self-inflicted injury to inform potential readmission screening. A retrospective cohort study of 11,269 individuals aged ≥ 15 years hospitalised for a major injury during 2013–2017 in New South Wales, Australia. Unplanned readmission and mortality up to 27-month post-injury were examined. Logistic regression was used to examine predictors of unplanned readmission. During the 27-month follow-up, 2700 (24.8%) individuals with non-self-inflicted and 98 (26.1%) with self-inflicted injuries had an unplanned readmission. Individuals with an anxiety-related disorder and a non-self-inflicted injury who were discharged home were three times more likely (OR: 3.27; 95%CI 2.28–4.69) or if they were discharged to a psychiatric facility were four times more likely (OR: 4.11; 95%CI 1.07–15.80) to be readmitted. Compared to individuals aged 15–24 years, individuals aged ≥ 65 years were 3 times more likely to be readmitted (OR 3.12; 95%CI 2.62–3.70). Individuals with one (OR 1.60; 95%CI 1.39–1.84) or ≥ 2 (OR 1.88; 95%CI 1.52–2.32) comorbidities, or who had a drug-related dependence (OR 1.88; 95%CI 1.52–2.31) were more likely to be readmitted. The post-discharge age-adjusted mortality rate following a self-inflicted injury (35.6%; 95%CI 29.9–41.8) was higher than for individuals with a non-self-inflicted injury (11.0%; 95%CI 10.4–11.8). Unplanned readmission after injury is associated with injury intent, age, and comorbid health. Screening for anxiety and drug-related dependence after major injury, accompanied by service referrals and post-discharge follow-up, has potential to prevent readmission.