Comparison of treatment of early-stage breast cancer among Nurses' Health Study participants and other Medicare beneficiaries.

Increasingly epidemiological cohorts are being linked to claims data to provide rich data for healthcare research. These cohorts tend to be different than the general United States (US) population. We will analyze healthcare utilization of Nurses' Health Study (NHS) participants to determine if studies of newly diagnosed incident early-stage breast cancer can be generalized to the broader US Medicare population.Analytic cohorts of fee-for-service NHS-Medicare-linked participants and a 1:13 propensity-matched SEER-Medicare cohort (SEER) with incident breast cancer in the years 2007-2011 were considered. Screening leading to, treatment-related, and general utilization in the year following early-stage breast cancer diagnosis were determined using Medicare claims data.After propensity matching, NHS and SEER were statistically balanced on all demographics. NHS and SEER had statistically similar rates of treatments including chemotherapy, breast-conserving surgery, mastectomy, and overall radiation use. Rates of general utilization include those related to hospitalizations, total visits, and emergency department visits were also balanced between the two groups. Total spending in the year following diagnosis were statistically equivalent for NHS and SEER ($36,180 vs. $35,399, p = 0.70).NHS and the general female population had comparable treatment and utilization patterns following diagnosis of early-stage incident breast cancers with the exception of type of radiation therapy received. This study provides support for the larger value of population-based cohorts in research on healthcare costs and utilization in breast cancer.