Polypharmacy and drug use in elderly Danish cancer patients during 1996 to 2006

Background: Elderly people are frequently exposed to polypharmacy defined as the simultaneous use of multiple drugs. However, data on drug use among elderly cancer patients are limited. The aims of this study were to describe drug use and polypharmacy in cancer patients aged ≥ 70 years and to describe their drug usage pattern prior to and following the cancer diagnosis. Methods: Population-based case-control study of all incident cancer cases in the Danish province of Funen (population 480,000) from 1996 to 2006. Data were collected from the Danish Cancer Registry and the Odense Pharmacoepidemiologic Database. Conditional logistic regression was used to compare drug use in cases and controls. Results: We identified 24,808 cancer cases and 99,299 controls. Of these, 47% were aged ≥ 70 years. At diagnosis, 35% of elderly cases used ≥ 5 drugs daily compared with 27% of controls, OR 1.76 (95% CI 1.66-1.86), and drug use was significantly higher as early as 18. months prior to the cancer diagnosis. In particular, use of analgesics, acid-suppressing drugs, and antibiotics increased markedly six months preceding cancer diagnosis. Mean daily drug use at diagnosis increased during the study period. Conclusion: Newly diagnosed elderly cancer patients use more drugs than the background population. Drug use increased markedly the last six months prior to the cancer diagnosis. This could suggest an increased symptom burden in patients prior to diagnosis and might serve as a warning signal for general practitioners.