Burden of multimorbidity and polypharmacy among cancer survivors: a population-based nested case-control study.

Purpose: Individuals living with cancer have been shown to have a higher burden of comorbid disease and multimorbidity in comparison to their cancer-free counterparts consequently, leaving them at risk of polypharmacy (i.e., ≥ 5 medications) and its potential negative effects. The primary aim of the current study was to examine the self-reported prevalence of and association between multimorbidity and prescription medication use in a population-based sample of adult cancer survivors (CS).

Methods: This retrospective, nested case-control study drew participant data from the Atlantic Partnership for Tomorrow's Health cohort. CS (n = 1708) were matched to 4 non-cancer controls (n = 6832) by age and sex. Prevalence of polypharmacy by number of chronic conditions and age was estimated with 95% CI. Logistic regression was used to examine the association between multimorbidity and polypharmacy while adjusting for sociodemographic and lifestyle factors. The comorbidity-polypharmacy score was also calculated as an estimate of disease burden.

Results: Multimorbidity was common in both CS (53%) and non-cancer controls (43%); however, a significantly higher percentage of CS reported multimorbidity (p < 0.001). Prescription medication use was also found to be significantly higher among CS (2.3 ± 2.6) compared to non-cancer controls (1.8 ± 2.3; p < 0.0001). Exploratory comorbidity-polypharmacy score analyses indicated that CS had a significantly higher overall disease burden than the age/sex-matched non-cancer controls.

Conclusions: As CS appear to be at a higher risk of multimorbidity and polypharmacy and by extension, increased healthcare burden, ongoing education on the prevention of medication-related harm, and interventions to reduce the occurrence of both co-morbid disease and unnecessary medications are warranted.