CRYPTOSPORIDIOSIS AMONG PATIENTS INFECTED WITH HUMAN-IMMUNODEFICIENCY-VIRUS - FACTORS RELATED TO SYMPTOMATIC INFECTION AND SURVIVAL

The authors reviewed the medical records of 194 human immunodeficiency virus (HIV)-positive patients newly diagnosed with cryptosporidiosis and all 3,564 patients with newly diagnosed acquired immunodeficiency syndrome (AIDS) at San Francisco General Hospital for the period 1986- 1992. The study was designed to address three questions: 1) How do AID S patients who present with cryptosporidiosis differ from other patien ts with AIDS? 2) What factors are associated with survival among AIDS patients with newly diagnosed cryptosporidiosis? 3) Does a diagnosis o f cryptosporidiosis impact survival after AIDS diagnosis? A total of 1 94 cases of cryptosporidiosis among HIV-infected patients were identif ied during the study period. Of the 194 patients, 109 (56%) had no pri or diagnosis of AIDS. These 109 patients represented 3.1% of the 3,564 newly diagnosed cases of AIDS in the same period. Among the 134 patie nts with CD4 T-lymphocyte counts performed within 3 months of Cryptosp oridium diagnosis, 34 (25%) had CD4 counts greater than 209 cells/ml. In a multivariate conditional logistic regression model, the incidence of Cryptosporidium was related to ethnicity (for blacks vs. whites, m atched odds ratio (OR) = 0.15, 95% confidence interval (CI) 0.03-0.73) , CD4 count (for a CD4 count of less than or equal to 53 cells/ml vs. >53 cells/ml, matched OR = 12.60, 95% CI 4.01-39.61), and age (for a 1 0-year increase, matched OR = 0.51, 95% CI 0.27-0.98). Two factors mea sured at the time of Cryptosporidium diagnosis were identified as bein g independently associated with survival (p < 0.001) in the proportion al hazards model: CD4 count less than or equal to 53 cells/ml versus > 53 cells/ml (relative hazard = 6.18, 95% CI 2.99-12.76) and hematocrit less than or equal to 37% versus >37% (relative hazard = 2.27, 95% CI 1.22-4.22). The median durations of survival in the four subgroups of Cryptosporidium-infected patients defined by these two variables diff ered significantly from each other (range, 204-1,119 days). Cryptospor idiosis as an initial AIDS-defining diagnosis was associated with an e levated relative hazard of death in comparison with other AIDS-definin g diagnoses (relative hazard = 2.01, 95% CI 1.38-2.93). These data ide ntify the groups of HIV-infected individuals at risk for presentation with symptomatic Cryptosporidium infection; the distinct survival patt erns among subgroups of those patients already infected with this para site; and the survival of AIDS patients with newly diagnosed cryptospo ridiosis relative to patients with other AIDS-defining conditions. Suc h information is necessary for the design of prospective studies, the development of prophylactic strategies, the evaluation of candidate th erapies, and the provision of prognostic information to patients.