Psychiatric hospitalizations among Canadian Armed Forces Veterans and former Royal Canadian Mounted Police members residing in Ontario: a retrospective cohort study

Objectives: Canadian Armed Forces (CAF) Veterans and former Royal Canadian Mounted Police (RCMP) members ("Veterans/former RCMP members") may be at increased risk of mental health disorders necessitating psychiatric hospitalization relative to non-Veterans. Differences in occupational experiences may further influence risk across subgroups of Veterans/former RCMP members. We compared the likelihood of a psychiatric hospitalization between Veterans/former RCMP members and non-Veterans residing in Ontario, Canada: (1) overall; by (2) sex and (3) length of service. Methods: This retrospective cohort study used administrative healthcare data to exact-match non-Veterans to Veterans/former RCMP members (4:1) residing in Ontario between March 18, 2002, and March 31, 2020, on age, sex, geography, and income. Sex-stratified Fine-Gray regression models were used to estimate the adjusted hazard ratio (aHR) of psychiatric hospitalizations within the first 10 years of follow-up. Results: In total, 2.5% of the 18,841 Veterans/former RCMP members (n = 476) and 0.9% of the 75,364 non-Veterans (n = 663) included in this study had a psychiatric hospitalization within the first 10 years of follow-up. Veterans/former RCMP members had a higher aHR of psychiatric hospitalizations than non-Veterans (aHR, 2.93; 95% CI, 2.61-3.29). Effects were stronger among females (aHR, 4.54; 95% CI, 3.34-6.17) and those with fewer years of service (e.g. 5-9 years aHR, 5.78; 95% CI, 4.27-7.83). Conclusion: The risk of psychiatric hospitalizations is almost three times higher among Veterans/former RCMP members compared to non-Veterans, with larger effects among females and individuals with fewer years of CAF/RCMP service. These occupational subgroups may benefit from targeted healthcare planning and resources.