IMPACT OF INTERHOSPITAL TRANSFERS ON OUTCOMES IN AN ACADEMIC-MEDICAL-CENTER - IMPLICATIONS FOR PROFILING HOSPITAL QUALITY

The purpose of this article is to determine whether a widely implement ed method of severity adjustment underestimated the risk of death and other outcomes among interhospital transfers tie, patients transferred from other acute care hospitals) and to examine the impact of this po tential bias on hospital outcomes profiles. The retrospective cohort s tudy was conducted at a midwestern academic medical center with 40,820 adult medical and surgical patients from 1988 to 1991, of whom 38,946 were direct admissions and 1,874 were interhospital transfers. Hospit al mortality, length of stay, and total charges in interhospital trans fers and direct admissions were compared using multivariable regressio n methods that adjusted for admission severity of illness and other po tential covariates (age, type of health insurance, diagnosis, emergent admission). Severity of illness was measured using the Medis-Groups m ethodology. Admission severity of illness was directly related (P < 0. 001) to rates of in-hospital death, length of stay, and charges, and w as higher among interhospital transfers; 49% of transfers had moderate to high severity, compared with 35% of direct admissions (P < 0.001). However, in a logistic regression model adjusting for severity and ot her covariates, the risk of in-hospital death was nearly two times (mu ltivariable odds ratio, 1.99; 95% confidence interval [CI], 1.64-2.42) higher in transfers than in direct admissions. In linear regression m odels, length of stay and charges were 1.47 (95% CI, 1.42-1.53) and 1. 40 (95% CI, 1.35-1.44) times higher, respectively, in transfers. Resul ts were consistent in medical and surgical admissions, when examined s eparately, and among individual diagnostic categories. Based on their findings, the authors estimate that, independent of quality of care, s everity adjusted mortality and length of stay would appear 17% and 8% higher, respectively, for hospitals in which 20% of patients were inte rhospital transfers than for hospitals in which 2% of patients were tr ansfers. In an academic medical center, interhospital transfers had po orer severity adjusted outcomes than patients admitted directly. Failu re to account for transfer status may produce biased performance profi les and, therefore, may create disincentives for hospitals to accept t ransfers from other acute case facilities.