Factors associated with pruritic papular eruption of human immunodeficiency virus infection in the antiretroviral therapy era

Background Pruritic papular eruption (PPE) of HIV is common in HIV-infected populations living in the tropics. Its aetiology has been attributed to insect bite reactions and it is reported to improve with antiretroviral therapy (ART). Its presence after at least 6 months of ART has been proposed as one of several markers of treatment failure. Objectives To determine factors associated with PPE in HIV-infected persons receiving ART. Methods A case-control study nested within a 500-person cohort from a teaching hospital in Mbarara, Uganda. Forty-five cases and 90 controls were enrolled. Cases had received ART for ≥ 15 months and had an itchy papular rash for at least 1 month with microscopic correlation by skin biopsy. Each case was individually matched with two controls for age, sex and ART duration. Results Twenty-five of 45 cases (56%) had microscopic findings consistent with PPE. At skin examination and biopsy (study enrolment), a similar proportion of PPE cases and matched controls had plasma HIV RNA < 400 copies mL^-1 (96% vs. 85%, P = 0·31). The odds of having PPE increased fourfold with every log increase in viral load at ART initiation (P = 0·02) but not at study enrolment. CD4 counts at ART initiation and study enrolment, and CD4 gains and CD8⁺ T-cell activation measured 6 and 12 months after ART commencement were not associated with PPE. Study participants who reported daily insect bites had greater odds of being cases [odds ratio (OR) 8·3, P < 0·001] or PPE cases (OR 8·6, P = 0·01). Conclusions Pruritic papular eruption in HIV-infected persons receiving ART for ≥ 15 months was associated with greater HIV viraemia at ART commencement, independent of CD4 count. Skin biopsies are important to distinguish between PPE and other itchy papular eruptions. What's already known about this topic? Papular pruritic eruption (PPE) of HIV is common in HIV-infected populations living in the tropics. PPE is characterized by symmetrically distributed itchy papules, worst on the extremities, with similar microscopic findings to insect bites or stings. What does this study add? Persistent or recurrent PPE in antiretroviral therapy (ART)-treated persons is associated with greater HIV RNA load at ART commencement but not during treatment. No association was found with CD4 count, CD4 gains and T-cell activation markers.