Is the Income Trajectory of Older Patients with Gastric Cancer Associated with Mood Disorders? A Nationwide Retrospective Cohort Study in South Korea

Mood disorders, influenced by income level and health-related stressors, are particularly concerning in financially and socially vulnerable older patients with gastric cancer. This study aimed to determine the relationship between income trajectory patterns and mood disorders within 5 years of cancer diagnosis in this population. This retrospective cohort study analyzed National Health Insurance Service-Senior cohort data from 2002 to 2019, focusing on older patients diagnosed with gastric cancer between 2008 and 2014. A latent class trajectory model was used to categorize the patients into five groups based on their income change patterns 6 years prior to cancer diagnosis up to 1 year post-diagnosis. We then used a Cox proportional hazards model to evaluate the association between income trajectories and mood disorder incidence and conducted subgroup analyses. Among the 4059 participants, 667 (16.4%) developed mood disorders within 5 years of cancer diagnosis. Cox regression analyses revealed that compared to the “consistently highest” income group 6 years prior to cancer diagnosis up to 1 year post-diagnosis, both the “consistently lowest” (hazard ratio [HR]: 1.38, 95% confidence interval [CI]: 1.05–1.81) and “decrease” (HR: 1.50, 95% CI: 1.15–1.95) groups had a significantly high risk of 5-year mood disorder incidence. Persistently low and declining income trajectories were associated with higher risks of mood disorders among older patients with gastric cancer. These findings support monitoring financial difficulties and mental health and strengthening links between cancer care, psychological support, and social support.