Specialization of Home Health Agencies to Deliver Care for Medicare Advantage Patients.

Importance: Enrollment in Medicare Advantage (MA) is expected to continue growing. Previous studies have examined differences in the use and quality of home health care between MA and traditional Medicare, but less is known about outcomes among patients receiving care from agencies with greater exposure to MA patients. Objective: To examine the association between home health agency (HHA) experience with caring for MA patients and quality of care delivered. Design, Setting, Participants: This cohort study included patients continuously enrolled in MA and who received HHA care in 2019. The data analysis was performed between July 16, 2024, and January 16, 2025. Exposure: Medicare beneficiaries who received home health care from agencies with differing levels of MA specialization. Main Outcomes and Measures: Primary outcomes included hospitalizations during the HHA episode and after HHA discharge (at 30 and 90 days), length of stay, and total number of visits. Secondary outcomes included postdischarge mortality and nursing home admission. The outcomes were measured using instrumental variable analysis. The treatment variable was a continuous measure of the HHA-level share of MA patients. The instrumental variable was the differential distance from the nearest MA-specialized HHA to nearest non-MA-specialized HHA (based on the 75th percentile of the HHA-level share of MA patients from January 1 to December 31, 2019 [ie, ≥36.4%]). Results: The study included 749 719 MA patients who received HHA care in 2019 (mean [SD] age, 76.2 [10.4] years; 61.6% female; 26.3% with dual eligibility), of whom 65.4% received care from an MA-specialized HHA and 34.6% received care from a non-MA-specialized HHA. A 1-mile increase in differential distance was associated with a lower likelihood of admission to more MA-specialized HHAs (0.3 percentage points; SE, 0.015 percentage points; F statistic, 450.73). In the instrumental variable analysis, receiving care from more specialized HHAs was associated with a shorter length of stay (coefficient [SE], -15.14 [2.84] days) and fewer total HHA visits (coefficient [SE], -9.40 [1.15] visits) alongside more hospitalizations and nursing home admissions after discharge from the HHA. Conclusion and Relevance: In this cohort study of MA patients who received HHA care, those receiving care from more MA-specialized HHAs had lower service use during the HHA episode, but no clear differences compared with non-MA-specialized HHAs were observed in care use after discharge. These findings are important given the costs associated with delivering HHA care and the expected growth in MA enrollment.