Mortality among patients with diffuse large B-cell lymphoma with mental disorders: a population-based study

Background — While mental disorders have been reported in patients with diffuse large B-cell lymphoma (DLBCL), studies examining their association with mortality are lacking.

Methods — We conducted a population-based study using linked administrative healthcare databases from Ontario, Canada. All patients with DLBCL aged ≥18 years treated with rituximab-based therapy between January 1st, 2005 and December 31st, 2017 were identified and followed until March 1, 2020. Mental disorders were defined as either pre-existing or post-diagnosis (after lymphoma treatment initiation). Cox proportional hazard models were used to estimate the adjusted hazard ratio (aHR) between mental disorders and outcomes 1-year and all-cause mortality, while controlling for covariates.

Results — We identified 10,299 patients with DLBCL; median age 67 years; 46% female; 28% with a pre-existing mental disorder. At 1-year follow-up, 892 (9%) had a post-diagnosis mental disorder, and a total of 2,008 (20%) patients died. Pre-existing mental disorders were not associated with 1-year mortality (aHR 1.06, 95% confidence interval [CI] 0.96-1.17, p = 0.25) while post-diagnosis disorders were (aHR 1.51, 95% CI 1.26-1.82, p = 0.0001). During a median follow-up of 5.2 years, 2,111 (22%) patients had a post-diagnosis mental disorder, and 4,084 (40%) patients died. Both pre-existing and post-diagnosis mental disorders were associated with worse all-cause mortality (pre-existing aHR 1.12, 95% CI 1.04-1.20, p = 0.0024; post-diagnosis aHR 1.63, 95% CI 1.49-1.79, p < 0.0001).

Conclusions — Patients with DLBCL and mental disorders had worse short-term and long-term mortality, particularly those with post-diagnosis mental disorders. Further studies are needed to examine mental health service utilization and factors mediating the relationship between mental disorders and inferior mortality.