Burden of cardiovascular diseases in breast cancer survivors: a 9-year retrospective cohort study based on regional medical data in Inner Mongolia China.

backgroundBreast cancer (BC) and cardiovascular diseases (CVD) shared many risk factors. Hitherto no studies revealing the burden of CVD and its subtypes in mainland Chinese BC patients exist. This study aimed to describe the incidence, prognosis and economic burden of CVD among BC survivors in Inner Mongolia.

methodsThis retrospective cohort study was conducted during 2012-2021, using data from the Inner Mongolia Regional Health Information Platform. BC patients were identified using diagnosis characters and ICD-10 code, and followed-up till new-onset CVD, death, or March 2021. New-onset CVD was documented by hospitalization, outpatient or medication records, and categorized into 12 subtypes. The incidence density, mortality density and medical costs were calculated. Subgroup analyses were also conducted by BC therapy status, nationality, GDP level and CVD subtypes.

resultsIn 29 516 BC patients included, the mean age was 52.03 ± 11.02, 16.55% were Mongolian. After 3.59 ± 2.34 years follow-up, we documented 12 527 new-onset CVD cases. The incidence density of CVD was 184.44 per 1000 person-years. Hypertension, arrhythmia, ischemic heart disease were the most common subtypes, with incidence density of 97.26, 79.80, and 53.90 per 1000 person-years. The incidence density peaked in the first year, especially the first three months, and then decreased gradually. BC patients with new-onset CVD had higher mortality density (33.41 vs. 19.63 per 1000 person-years), and bear higher expenses burden of average annual costs for outpatients (2349.20 vs. 2319.08 CNY) than those without. Patients residing in lower GDP areas had higher all-cause mortality density (35.37 vs. 31.45 per 1000 person-years), but higher average annual for hospitalization (18770.60 vs. 15827.69 CNY) than their counterpart. As for CVD subtypes, BC patients with heart failure and arrhythmia showed the top 2 highest mortality density and economic burden.

conclusionsAmong BC survivors in Inner Mongolia, hypertension and arrhythmia were the most common CVD subtypes, especially in the first three-month after BC diagnosis. Those with arrhythmia, heart failure, or from lower-GDP areas showed poorer prognosis. Results highlighted the urgent need for cardio-protective strategies for BC patients, especially at the first three-month post-diagnosis, for those from economically disadvantaged regions, targeting hypertension, arrhythmia and heart failure.