Association Between Nonfatal Self-Injury and Survival Following a Cancer Diagnosis: A Comparative Population-Based Cohort Study

Background: Nonfatal self-injury (NFSI) following a cancer diagnosis is a very serious mental health sequalae. Whether NFSI has an impact on patient outcomes is unknown. To help determine the impact and burden of NFSI in cancer care, this study examined the association between NFSI following a cancer diagnosis and subsequent overall survival (OS). Methods: A retrospective population-based cohort study using linked administrative health care included patients with a new cancer diagnosis in 2007 through 2019. The exposure was NFSI (emergency department visit for self-injury of intentional or undetermined intent), treated as time-varying. The outcome was OS, as death from any cause measured from cancer diagnosis. Extended Cox multivariable models examined the association between NFSI and OS, adjusting for patient, cancer, and mental health history characteristics. Results: Of 806,910 patients, 2,482(0.31%) had NFSI at a median of 29 months (IQR, 11-57) from cancer diagnosis. Of those, 81 had >1 NFSI event. Patients with NFSI had inferior OS compared with those who had not yet experienced an NFSI (adjusted hazard ratio [HR], 1.73; 95% CI, 1.61-1.85). When treating NFSI as a count variable, there was an association between each additional NFSI and OS (adjusted HR, 1.17; 95% CI, 1.08-1.26). Conclusions: NFSI following a cancer diagnosis was independently associated with inferior OS. This finding highlights NFSI as a crucial event for patients with cancer and supports the importance of identifying and providing treatment for patients with cancer with cancer-related distress, such as marked by higher risk of NFSI.