MEASURING PROGNOSIS AND CASE-MIX IN HOSPITALIZED ELDERS - THE IMPORTANCE OF FUNCTIONAL STATUS

OBJECTIVE: Although physical function is believed to be sum important predictor of outcomes in older people, it has seldom been used to adju st for prognosis or case mix in evaluating mortality rates or resource use. The goal of this study was to determine whether patients' activi ty of daily living (ADL) function on admission provided information us eful ire adjusting for prognosis and case mix after accounting: for ro utine physiologic measures and comorbid diagnoses. SETTING: The genera l medical service of a teaching hospital. PARTICIPANTS: Medical inpati ents (n = 823) over age 70 (mean age 80.7, 68% women). MEASUREMENTS: I ndependence in ADL function on admission was assessed by interviewing each patient's primary nurse. We determined the APACHE II Acute Physio logy Score (APS) and the Charlson comorbidity score from chart review. Outcome measures were hospital and 1-year mortality, nursing home use in the 90 days following discharge, and cost of hospitalization. Pati ents were divided into four quartiles according to the number of ADLs in which they were dependent. MAIN RESULTS: ADL category stratified pa tients into groups that were at markedly different risks of mortality and higher resource use. For example, hospital mortality varied from 0 .9% in patients dependent in no ADL on admission, to 17.4% in patients dependent in all ADLs. One-year mortality ranged from 17.5% to 54.9%, nursing home use from 3% to 33%, and hospital costs varied by 53%. In multivariate analyses controlling for APS, Charlson scores, and demog raphic characteristics, compared with patients dependent in no ADL, pa tients dependent in all ADLs were at greater risk of hospital mortalit y (odds ratio [OR] 13.7: 95% confidence interval [CI] 3.1-58.8), 1-yea r mortality (OR 4.4; 2.7-7.4), and 90-day nursing home use (OR 14.9; 6 .0-37.0). The DRG-adjusted hospital cost was 50% higher for patients d ependent in all ADLs. ADL function also improved the discrimination of hospital and 1-year mortality models that considered APS, or Charlson scores, or both. CONCLUSIONS: ADL function contains important informa tion about prognosis and case mix beyond that provided by routine phys iologic data and comorbidities in hospitalized elders. Prognostic and case-mix adjustment methods may be improved if they include measures o f function, as well as routine physiologic measures and comorbidity.