Psychological distress 12 years following injury in New Zealand: findings from the Prospective Outcomes of Injury Study-10 years on (POIS-10)

BACKGROUND: Injuries can have detrimental impacts on mental health, even after physical recovery. In our Prospective Outcomes of Injury Study (POIS), 25% of participants experienced psychological distress (assessed using the Kessler 6) three months after a sentinel injury event (SIE), declining to 16% at 24 months post-SIE. Internationally, studies of hospitalised patients found distress persisted beyond 24 months post-injury and remained higher than the general population. However, most studies only assessed distress at one timepoint, relied on long-term recall, or were limited to small samples or specific injury types. Therefore, we aim to describe the prevalence of psychological distress 12 years post-SIE and to investigate pre-injury, injury-related and early post-injury characteristics associated with long-term distress. METHODS: POIS is a longitudinal cohort study of 2856 New Zealanders injured between 2007 and 2009, who were on the national injury insurer, Accident Compensation Corporation entitlement claims’ register. Of these, 2068 POIS participants completed an interview at 24 months and agreed to further contact. They were invited to a follow-up interview 12 years post-SIE which included the Kessler-6 (K6), the psychological distress outcome of interest. Data about a range of pre-injury, injury-related and early (3 months) post-injury characteristics were collected via earlier interviews or administrative data sources (e.g. hospital discharge data). RESULTS: Twelve years post-SIE, 1543 (75%) people were re-interviewed and 1526 completed the K6; n = 177 (12%) reported psychological distress. Multivariable modified Poisson regression models found pre-injury characteristics were associated with an increased risk of clinically relevant distress at 12 years, i.e. having inadequate income, identifying as Māori, Pacific or Asian and having one mental health condition. Early post-injury psychological distress and dissatisfaction with social relationships also increased risk. However, being older was associated with a reduced risk of distress. CONCLUSION: Clinically relevant distress persists long-term post-injury among adults with varying injury severity, types and causes, and at higher prevalence than in the general population. Early identification of injured people at risk of long-term psychological distress provides opportunities for timely interventions to reduce psychological distress.