Integrated health systems and medical care quality during the COVID-19 pandemic

To examine differences between patients treated in integrated systems of care and patients treated outside of such systems during the COVID pandemic in the use of primary and preventive care, emergency services, inpatient services, and mortality.

Data are used from all enrollees in traditional Medicare aged 66 and older.

Difference-in-differences estimates are calculated from the pre-COVID time period (January 2019-February 2020) to the initial COVID time period (March-May 2020) and the ongoing COVID time period (June 2020-December 2021) for patients treated by primary care physicians working in a health system versus not, and by the type of health system.

Medicare claims data are used to measure monthly claims for office and telehealth visits, mammography, colon cancer screening, inpatient/emergency department visits, and death. Patients are assigned to primary care physicians using common algorithms. Physician membership in a health system is determined from a previously generated dataset.

Relative to the pre-COVID period, patients treated in health systems fared no better in maintaining primary care access than patients treated outside of such systems (DID estimate on receipt of office care or telehealth visit = -4%; p < 0.001). In the ongoing COVID time period, non-COVID mortality rose by less in health systems (DID estimate = -0.9%; p < 0.001) and health system patients experienced a greater decline in the use of the emergency department (DID estimate = -1.2%; p < 0.001) and emergency/urgent inpatient care for non-COVID conditions less (DID estimate = -0.7%; p < 0.001).

Health systems were associated with reduced occurrence of death and adverse medical events, although the effect magnitudes are modest. This reduction appears unrelated to the use of primary care and should be considered in the context of our evolving understanding of the advantages and disadvantages of health systems.