Influence of physician specialty on outcomes after acute ischemic stroke

Abstract

Background: Specialist care has been shown to improve outcomes for several complex medical conditions. For patients with ischemic stroke, prior studies have suggested that admission to the care of neurologists is associated with better outcomes, but these studies may have incompletely controlled for confounding prognostic differences.

Objective: The objective of this study was to evaluate whether admission to the care of a neurologist is associated with improvement in outcomes of stroke patients after controlling for initial prognostic differences.

Design: This was a retrospective cohort study.

Setting: Participating in the study were 113 U.S. academic hospitals.

Patients: Demographic and clinical data for all ischemic stroke patients admitted through emergency departments from 1997 to 1999 were collected from an administrative database.

Measurements: In traditional analyses, we evaluated attending physician specialty as a predictor of in-hospital mortality. In grouped-treatment (GT) analyses, a method based on the instrumental variable approach that bypasses selection bias, the hospital rate of stroke admission to neurologists was used as the predictor. We used generalized estimating equations for all analyses, adjusting for demographics, urgency, comorbid illness severity, and treatment volume.

Results: Of 26,925 ischemic stroke patients, 60% were admitted to the care of neurologists. In univariate analysis, risk of in-hospital mortality in cases admitted to neurologists (4.6%) was lower than that for those admitted to generalists (9.5%; P < .001). Adjustment for individual-level characteristics did not alter the association (0.60 OR, 95% CI, 0.50-0.72; P < .001). However, no advantage to neurologist admission was demonstrated in GT analysis, with mortality rates similar at hospitals admitting different proportions of ischemic stroke cases to neurologists (1.02 OR, 95% CI, 0.79-1.30; P = .90).

Conclusions: Differences in ischemic stroke outcomes between neurologists and generalists may be a result of differences in initial prognosis because outcomes are no better at hospitals that admit patients to the care of neurologists more frequently.