The association of continuity of care and risk of mortality in breast cancer patients with cardiometabolic comorbidities

Objective: The association of continuity of care (COC) among providers and mortality risk for breast cancer patients with comorbidities is not sufficiently studied. Design: A retrospective cohort study using the 2006-2014 Surveillance, Epidemiology and End Results (SEER)-Medicare data. Participants: Newly diagnosed female breast cancer patients (n = 57,578) with comorbidities (hypertension, hyperlipidemia, and/or diabetes). Methods: All-cause mortality was assessed annually for up to 5 years. COC was estimated using the Bice-Boxerman index, which included: 1) specialty COC capturing continuity of visits to the same provider type (Primary Care Physicians, Oncologists, and Other specialists) and 2) individual COC capturing continuous care to the same provider regardless of provider specialty. Cox proportional hazards models estimated the hazard ratio (HR) of all-cause mortality across quartile of the COC index. Results: Mortality was positively associated with advanced tumor stages and number of comorbidities (p < 0.05). Patients with high specialty COC (4th vs. 1st quartile, HR 1.34, 95%CI 1.29-1.40) had higher risks of mortality compared with those with low specialty COC. However, patients with high individual COC (4th vs. 1st quartile, HR 0.53, 95%CI 0.51-0.54) had lower risks of mortality compared to those with low individual COC. Conclusion: Receiving care from fewer providers is associated with lower mortality and from more types of provider is associated with higher mortality. The results might be confounded by uncontrolled factors and provoke the need for alternative patient care models that recognize the balance between appropriate subspecialties and minimizing the fragmentation of care within and across subspecialties.