Features and outcome of Pneumocystis carinii pneumonia according to risk category for HIV infection.

A retrospective study of Pneumocystis carinii pneumonia (PCP) was undertaken to examine differences between the presentation and outcome of PCP in AIDS patients from different risk categories for HIV infection. There were 176 PCP episodes recorded in 126 patients from the following risk categories: 69 intravenous drug misusers (IDMs), 36 homosexually infected men and 21 heterosexually infected patients. Most clinical features did not differ significantly between the 3 groups but hypercapnia was almost exclusively seen in IDMs and, if recorded, was associated with a poorer survival. Pneumothorax was more likely to complicate PCP in IDMs and, although present in all groups, concomitant bacterial respiratory infections were more common in IDMs. Recovery from PCP and the incidence of adverse events during treatment did not differ according to risk category. Subsequent survival time was shorter amongst IDMs, but the uptake of antiretrovirals in this group was significantly lower. We conclude that there are few differences in the presentation of PCP between IDMs and other risk categories for HIV infection and that these do not influence the outcomes of illness. The lower post-PCP survival in IDMs can be accounted for by a reduced uptake of antiretroviral drugs by this group.