Abstract
BACKGROUND: Life dissatisfaction varies with different factors--particularly in the presence of chronic conditions, such as cancer. The combination of cancer and mental health disorders may increase life dissatisfaction due to lowered resilience against stress. We sought to determine if life dissatisfaction is higher in Canadians aged 40 and above with cancer compared to the cancer-free population and if there is a synergistic effect between cancer and mental health disorder on life dissatisfaction. METHODS: We conducted a cross-sectional study using the 2015-2016 Canadian Community Health Survey. We included 67,294 subjects aged 40+, and evaluated the association between cancer, mental health disorders, and life dissatisfaction using logistic regression and odds ratios (ORs) while adjusting for age, sex, marital status, education level, and chronic conditions. Relative excess risk due to interaction (RERI), attributional proportion due to interaction (AP), and Synergy index (S-index), were calculated to determine the significance of additive interaction. RESULTS: Compared to the cancer-free population, life dissatisfaction was higher in patients with cancer (OR 2.44, 95% CI: 1.88-3.16) and mental health disorders (OR 5.17, 95% CI: 4.56-5.85). The adjusted ORs for life dissatisfaction were 2.45 (95% CI: 1.74-3.43) and 5.17 (95% CI: 4.55-5.87) for cancer and mental health disorders, respectively, but when both conditions were present, the OR increased to 12.50 (95% CI: 8.40-18.62). The results suggested a synergistic interaction (RERI: 5.89 [95% CI: 0.91-10.87]; AP: 0.47 [95% CI: 0.25-0.69]; and S-index: 2.05 [95% CI: 1.30-3.23]). CONCLUSION: This study showed higher life dissatisfaction in cancer and mental health disorder patients. A synergistic effect was detected between cancer and mental health disorder on life dissatisfaction. These results suggest cancer patients with mental health disorders require additional support and psychological resources to improve their quality of life.