Increased morbidity evaluated on hospital contacts and prescriptions among 100,834 Danish breast cancer survivors

Background Cardiovascular disease competes with breast cancer (BC) as the leading cause of death for females diagnosed with breast cancer. Not much is known concerning morbidity and medicine use in the short and long term after a BC diagnosis. Aim The aim of this study was to determine acute and long-term morbidity in Danish women treated for BC. Method A nationwide registry-based cohort study of 100,834 BC patients identified in the clinical database of Danish Breast Cancer Cooperative Group (DBCG) and 1,100,320 (10 per patient) age-matched Danish women without BC, serving as controls. Morbidity was studied using complete data on hospital contacts and medicinal use. Results The risk of hospital contacts was significantly increased in BC survivors compared with controls evaluated both by means of Cox regression and negative binomial regression analysis both during and after cessation of breast cancer treatment. Young age at breast cancer diagnosis was associated with the most pronounced increase in risk of hospital contacts, both during and after cessation of BC treatment. Medicinal use was significantly increased among BC patients compared to controls, both during (HR 1.27 (1.26–1.28), p < 0.0001) and after BC treatment (HR 1.18 (1.17–1.19), p < 0.0001, and present for all subgroups of medicine. Conclusion Overall, BC survivors have a pronounced increase in hospital contacts and medicinal use compared to women without BC. Premenopausal status at BC diagnosis was associated with an overall higher excess morbidity and a higher burden both during and after treatment.