The cerebrospinal fluid HIV risk score for assessing central nervous system activity in persons with HIV

Detectable human immunodeficiency virus (HIV) RNA in the cerebrospinal fluid (CSF) is associated with central nervous system (CNS) complications. We developed the CSF HIV risk score through prediction modeling to estimate the risk of detectable CSF HIV RNA (threshold >50 copies/mL) to help identify persons who might benefit most from CSF monitoring. We used baseline data from 1,053 participants receiving combination antiretroviral therapy who were enrolled in the 6-center, US-based CNS HIV Antiretroviral Therapy Effects Research (CHARTER) prospective cohort in 2004-2007. Plasma HIV RNA, CNS penetration effectiveness, duration of combination antiretroviral therapy, medication adherence, race, and depression status were retained correlates of CSF HIV RNA, displaying good discrimination (C statistic = 0.90, 95% confidence interval (CI): 0.87, 0.93) and calibration (Hosmer-Lemeshow P = 0.85). The CSF HIV risk score ranges from 0 to 42 points, with a mean of 15.4 (standard deviation, 7.3) points. At risk scores greater than 25, the probability of detecting CSF HIV RNA was at least 42.9% (95% CI: 36.6, 49.6). For each 1-point increase, the odds of detecting CSF HIV RNA increased by 26% (odds ratio = 1.26, 95% CI: 1.21, 1.31; P < 0.01). The risk score correlates with detection of CSF HIV RNA. It represents an advance in HIV management and monitoring of CNS effects, providing a potentially useful tool for clinicians.