At Partners» Pioneer ACO, although most physicians (88 %) had
at least some patients attributed to them, it accounted for a small part of their panel (less than 5 %).
Hospitalists typically work in shifts; therefore, within the same hospital,
patients treated by hospitalists are plausibly quasi-randomized to a given physician based on when
patients become sick and based on hospitalists» work schedule.34 We defined hospitalists using a validated approach: general internists who filed
at least 90 % of their total evaluation and management billings in an inpatient setting.35 Second, to evaluate whether our findings were sensitive to how we
attributed patients to physicians, we tested the following 2 alternative attribution methods:
attributing patients to physicians who had the largest number of evaluation and management claims and
attributing patients to physicians who billed the first evaluation and management claim for a given hospitalization.25, 36,37 Third, within some hospitals, male internists may be more likely to work in intensive care units and have severely ill
patients.