Physician's Case Volume of ICU Pneumonia Admissions and In-hospital Mortality

RATIONALE: Although several studies have investigated volume-outcome relationships for surgical procedures, there has been no such study of intensive care unit (ICU) patients admitted for pneumonia. OBJECTIVES: This study examines associations between in-hospital mortality of ICU-admitted pneumonia patients and their attending physician~s case volume. METHODS: We used 2002-2004 claims data from Taiwan~s National Health Insurance for all 87,479 adult ICU admissions for pneumonia. Patients were assigned to one of four groups, on the basis of their physician~s ICU pneumonia case volume (low volume, <36 cases; medium volume, 37-114 cases; high volume, 118-314 cases; and very high volume, > or =315 cases). Generalized estimating equations (conditional on hospital, and unconditional) were used, adjusting for physician demographics and specialty, hospital characteristics, patient characteristics (including clinical severity and comorbidities), and physician-level random effect (clustering effect) to assess whether physicians~ case volume predicts inhospital mortality. MEASUREMENTS AND MAIN RESULTS: Inhospital mortality systematically declined with increasing physician case volume: 14.7, 14.3, 11.4, and 8.1% from low-volume to very-high-volume groups. Adjusted unconditional odds of mortality among lowvolume physicians~ patients were 2.04 times those of very-high-volume physicians, 1.35 times that of highvolume physicians, and 1.09 times those of medium-volume physicians (all P < 0.001). The relationship is sustained when the odds are estimated conditional on hospital, when initial 5-day mortality is separated from 30-day mortality, and when pulmonologists~ and critical care specialists~ patients are studied separately. CONCLUSIONS: Physician volume significantly predicts inpatient mortality among ICU patients with pneumonia. Detailed study of clinical approaches, decision algorithms, and treatment plans of high-volume physicians is recommended to identify possible mediating factors in this phenomenon.