VARIATIONS IN MEDICAL-CARE FOR HIV-RELATED PNEUMOCYSTIS-CARINII PNEUMONIA - A COMPARISON OF PROCESS AND OUTCOME AT 2 HOSPITALS

Background: Institutional variation in Be quality of medical care may he evaluated by examining process measures, such as use of diagnostic procedures or treatment modalities, ol outcome measures, such as morta lity. We undertook this study to examine variations in both process an d outcome of care for patients with HIV-related Pneumocystis carinii p neumonia (PCP) at two geographically diverse, HIV-experienced, public municipal hospitals. Design: Retrospective review of hospitalized pati ents diagnosed as having PCP cared for at two municipal hospitals from 1988 to 1990. At hospital A, charts of all patients diagnosed as havi ng PCP were abstracted (n=209); at hospital B, a random sample of 15% were abstracted (n=136). Results: Among all hospitalized patients diag nosed as having PCP, the frequency of making a definitive diagnosis of PCP (as opposed to treating empirically) differed markedly at the two hospitals (85% in hospital A vs 26% in hospital B; p<0.001), as did t he use of intensive care (18% vs 3%; p<0.001) and ''do-not-resuscitate '' orders (39% vs 14%; p<0.001), although the timing of starting anti- Pneumocystis medications (89% vs 88% within the first 2 hospital days) and the use of corticosteroids (21% vs 23%) were similar. Despite dif ferences in the process of care, survival rates were similar at the tw o institutions (75% vs 76%; p=0.8) and remained similar when logistic regression was used to control for demographic variables and severity of illness (odds ratio for survival, hospital B vs A, 1.2 [95% confide nce interval, 0.7, 2.0]). The 95% confidence intervals (0.7,; 2.0), ho wever, were consistent with a considerable (and clinically) significan t) disparity in survival (from 30% lower to a twofold higher odds of s urvival). Sample size calculations shelved that a sample of 10 cases i n each hospital would be required to detect the observed difference in definitive diagnosis rates (85% vs 26%), but 722 cases in each hospit al would he required to detect a relevant difference in mortality. Con clusions: The process of care for hospitalized patients with PCP in th ese two institutions differed considerably, but the survival rates wer e not significantly different, even after adjusting for confounding fa ctors. While sample sizes available at the individual institutions wer e sufficient for evaluation of the process of care, they did not provi de the power necessary to evaluate outcomes. Comparisons of outcomes s uch as mortality between individual hospitals may not have the statist ical power to exclude important differences.