Association of co-medication quality with chemotherapy-related adverse drug reactions and survival in older colorectal cancer patients.

BACKGROUND Evidence about the clinical relevance of appropriate co-medication among older colorectal cancer (CRC) patients is sparse. METHODS A cohort study was conducted with 3,239 CRC patients aged 65 years and older. To assess co-medication quality, we calculated the total Fit fOR The Aged (FORTA) score and its sub-scores for medication overuse, underuse, and potentially inappropriate medication use. Multivariable Cox proportional hazards or logistic regression models were performed to evaluate the association of co-medication quality with up to 5-year overall survival, CRC-specific survival, and chemotherapy-related adverse drug reactions (ADRs). RESULTS Overall, 3,239 and 1,209 participants were included in analyses on survival and ADRs, respectively. The hazard ratios [95%-confidence intervals] for the total FORTA score ≥ 7 vs. 0-1 points were 1.83 [1.40-2.40] and 1.76 [1.22-2.52] for up to 5-year overall and CRC-specific survival, respectively. Worse up to 5-year OS and CSS was also evident for FORTA sub-scores for PIM use and overuse whereas no association was observed for underuse. Although results for the total FORTA and potentially inappropriate medication score were much stronger among patients receiving chemotherapy, no significant associations with chemotherapy-related ADRs were observed. Moreover, associations were particularly strong among men and rectal cancer patients as compared to women and colon cancer patients. CONCLUSIONS Poor total co-medication quality was significantly associated with worse up to 5-year overall and CRC-specific survival. Randomized controlled trials are needed to test whether improved cancer co-medication management in older CRC patients prolongs survival.