CD4 cell count and the risk of infective and non-infective serious non-AIDS events in HIV-positive persons seen for care in Italy

INTRODUCTION Serious non-AIDS events (SNAE) are frequent in HIV patients receiving cART. Current CD4 count was shown to be more strongly associated with infective compared to not-infective SNAE and unable to predict cardiovascular events. We investigated the relationship between baseline and current CD4 count and the risk of both infective and non-infective SNAE in HIV-positive patients according to current ART use. METHODS We included all HIV-positive persons enrolled in the ICONA Foundation Study cohort who had at least one follow-up visit. SNAE were grouped in infective (pneumonia, sepsis, endocarditis and meningitis) and non-infective (malignancies, chronic kidney disease, cardiovascular events, hepatic events and pancreatitis) aetiology. Incidence of these event groups were calculated overall and according to baseline and current CD4 count (grouped as 0-200, 201-350, 351-500, 501-750, and >750 cells/mm(3)). Participants' follow-up accrued from the date of enrolment (baseline) to a diagnosis of SNAE or their last visit. An event was defined the first time one of the considered SNAE occurred so that each person contributed a single event. A Poisson regression model for each of the two endpoints was used. RESULTS A total of 10,822 patients were included (25.3% females, 38.2% heterosexuals) and 26.6% had hepatitis co-infections. Median age was 36 (IQR 31-42) years. Overall, 423 not-infective and 385 infective SNAE were included. The most frequent non-infective SNAE were malignancies (n=202) and the most frequent infective SNAE were pneumonia (n=289). Crude rates of non-infective SNAE were 0.78, 1.08 and 0.80/100 PYFU, and those of infective SNAE were 1.00, 0.51 and 0.66/100 PYFU in ART naive, currently off and currently on ART patients, respectively. Higher current CD4 count was associated with reduced risk of both infective and non-infective SNAE in naives and in patients on ART (Table 1). The association was less strong in the group which suspended ART (for non-infective SNAE the p value for interaction between current log-CD4 and ART-status, p=0.004). Conversely, we found no association between baseline CD4 count and risk of non-infective SNAE in people treated with ART (p value for interaction = 0.0001). When CVD were considered separately, there was no association with CD4 count (not shown). CONCLUSIONS Our findings show that, differently from ART naive, in ART-treated patients, non-infective SNAE are predicted by current but not by baseline CD4, suggesting that immune restoration is crucial to prevent these events.