Aim: Despite growing recognition of the impact of comorbidities on the care and health outcomes of cancer survivors, there is little data on comorbidity available in the Australian context which may inform the development of better policy and practice. This study aims to assess the development of comorbidities among Australian women treated with endocrine therapy for hormone-dependent breast cancer.
Methods: Prescription claims data from the Australian Government’s Pharmaceutical Benefit Scheme 10% sample were utilised. Comparisons were made between women who initiated endocrine therapy between year 2004 and 2011 and an age- and sex-matched control group (at 1:5 ratio) without any dispensing record of anti-neoplastic agents during the study period. Prescription claims data were used to identify comorbidities and classified with the Rx-Risk-V model. A Cox regression model was used to evaluate the development of specific comorbidities over time and was adjusted for number of baseline comorbidities.
Results: Gastric acid disorders, heart failure/hypertension and dyslipidemia were the top three most prevalent comorbidities among breast cancer survivors prior to the initiation of endocrine therapy. The hazard ratio (HR) for developing depression (HR 1.32, 95% CI 1.20-1.47), osteoporosis (HR 1.26, 95% CI 1.11-1.42), cardiovascular disease (HR 1.19, 95% CI 1.07-1.33) and diabetes mellitus (HR 1.25, 95% CI 1.05-1.49) were higher among breast cancer survivors compared to women without cancer. The HR for developing dyslipidemia (HR 0.87, 0.78-0.98) was lower among breast cancer survivors. There was no significant differences between the two groups for reactive airway disease and gastric acid disorders.
Conclusion: Comorbidity is more prevalent among breast cancer survivors than women without cancer. Our results further support the need to develop appropriate models of care to address multiple chronic conditions experienced by breast cancer survivors.Â