Diagnostic accuracy of three clinical case definitions for advanced HIV disease.

OBJECTIVE: To assess the accuracy of three clinical case definitions for advanced HIV disease: the World Health Organization (WHO) case definition, and the original and revised Caracas case definitions. DESIGN: Retrospective chart review. SETTING: A clinic for patients with all stages of HIV infection at the Johns Hopkins Hospital, Baltimore, [correction of Bethesda] Maryland, USA, a tertiary care university hospital. PATIENTS, PARTICIPANTS: Two hundred and twenty-four HIV-positive adults who underwent initial evaluation between 1 January 1990 and 31 December 1990. MAIN OUTCOME MEASURES: A score for each definition was assigned based on initial evaluation. The sensitivity, specificity, and predictive values were calculated using the Centers for Disease Control (CDC) staging criteria, and results were correlated with total CD4 cell counts. RESULTS: The sensitivities of the WHO, and the original and revised Caracas definitions were 40, 67, and 60%, respectively, using CDC disease stage IV as a positive standard. Specificities were between 99 and 100%, using CDC stage II-III disease as a negative standard. Mean CD4 cell counts for patients with positive scores were 184, 160, and 158 x 10(6)/l, respectively, compared to 191 x 10(6)/l for CDC stage IV patients. Sensitivity was lower when the positive standard was expanded to include all patients with CD4 cell counts less than 200 x 10(6)/l. CONCLUSIONS: In our study population, case definitions were specific, but only moderately sensitive for advanced HIV disease. Prospective studies should be conducted in diverse geographic regions, using lymphocyte or CD4 cell counts when possible.

PIP: The 1st case definition for AIDS was developed by the Centers for Disease Control (CDC) in 1982. WHO adopted CDC definitions for use in some countries and also developed a clinical case definition where HIV serology tests were not feasible. A multivariate analysis of data of Brazilian AIDS patients with positive HIV serology provided the basis for the Caracas definition in 1989 and it subsequent revision. The accuracy of these 3 clinical definitions was evaluated to see their predictive value in an advanced stage of AIDS. The records of 224 HIV-positive adults were reviewed in 1990. Scores were assigned to various symptoms. 80% of men and 20% of women with a median age of 33 years; 1/4 were white and 2/3 were black. 1/3 were homosexuals and 1.2 were iv drug users. 139 were asymptomatic (CDC stage I-II) and 85 were symptomatic (CDC stage IV). 58 patients had total CD4 cell counts of over 500 x 1 million/1; 91 had 200-500 x 1 million/l; and 70 had 200 x 1 million/1. 48 were taking zidovudine and Pneumocytis carinii drugs. The sensitivities of the WHO, original Caracas definition, and revised Caracas definition were 40%, 67%. and 60%, respectively, with 99-100% specificities and positive predictive values of 97-100%. The mean CD4 cell counts for the WHO, original and revised Caracas definitions were 184, 160, and 158 x 1 million/1, respectively, compared with 199 x 1 million/1 of patients with CDC stage IV disease. The predictive values of the 3 definitions for CD4 cell counts 200 x 1 million/1 reached 62%, 73%, and 71% vs. only 59% for CDC stage IV patients. The combination of stage IV symptoms or a CD4 cell count 200 x 1 million/1 produced sensitivities of 31%, 53%, and 47%, respectively, with 100% specificity and positive predictive values. The definitions were highly specific, but only moderately sensitive for advanced AIDS; the Caracas definitions were more sensitive than the WHO definition.