Association Between Treatment by Locum Tenens Internal Medicine Physicians and 30-Day Mortality Among Hospitalized Medicare Beneficiaries

IMPORTANCE Use of locum tenens physicians has increased in the United States, but information about their quality and costs of care is lacking. OBJECTIVE To evaluate quality and costs of care among hospitalized Medicare beneficiaries treated by locum tenens vs non-locum tenens physicians. DESIGN, SETTING, AND PARTICIPANTS A random sample of Medicare fee-for-service beneficiaries hospitalized during 2009-2014 was used to compare quality and costs of hospital care delivered by locum tenens and non-locum tenens internal medicine physicians. EXPOSURES Treatment by locum tenens general internal medicine physicians. MAIN OUTCOMES AND MEASURES The primary outcome was 30-day mortality. Secondary outcomes included inpatient Medicare Part B spending, length of stay, and 30-day readmissions. Differences between locum tenens and non-locum tenens physicians were estimated using multivariable logistic regression models adjusted for beneficiary clinical and demographic characteristics and hospital fixed effects, which enabled comparisons of clinical outcomes between physicians practicing within the same hospital. In prespecified subgroup analyses, outcomes were reevaluated among hospitals with different levels of intensity of locum tenens physician use. RESULTS Of 1 818 873 Medicare admissions treated by general internists, 38 475 (2.1%) received care from a locum tenens physician; 9.3%(4123/44 520) of general internists were temporarily covered by a locum tenens physician at some point. Differences in patient characteristics, demographics, comorbidities, and reason for admission between locum tenens and non-locum tenens physicians were not clinically relevant. Treatment by locum tenens physicians, compared with treatment by non-locum tenens physicians (n = 44 520 physicians), was not associated with a significant difference in 30-day mortality (8.83% vs 8.70%; adjusted difference, 0.14%; 95% CI, -0.18% to 0.45%). Patients treated by locum tenens physicians had significantly higher Part B spending ($1836 vs $1712; adjusted difference, $124; 95% CI, $93 to $154), significantly longer mean length of stay (5.64 days vs 5.21 days; adjusted difference, 0.43 days; 95% CI, 0.34 to 0.52), and significantly lower 30-day readmissions (22.80% vs 23.83%; adjusted difference, -1.00%; 95% CI -1.57% to -0.54%). CONCLUSIONS AND RELEVANCE Among hospitalized Medicare beneficiaries treated by a general internist, there were no significant differences in overall 30-day mortality rates among patients treated by locum tenens compared with non-locum tenens physicians. Additional research may help determine hospital-level factors associated with the quality and costs of care related to locum tenens physicians.