Cognitive change over one year among older adults with HIV and a low nadir CD4 cell count

Background Evidence regarding the risk of cognitive decline conferred by a low nadir CD4 cell count and increasing age in people living with HIV is mixed. The objective of this study was to assess the change in cognition over one year among older adults with well-controlled HIV infection and a history of low nadir CD4 cell count compared with the change in a matched non-HIV sample. Methods We recruited 50 HIV+ aviremic individuals 40 years or older, on stable antiretroviral treatment and with a nadir CD4 < 200 cells/μL, and seventeen matched HIV-negative individuals. Neuropsychological testing was performed twice, one year apart; an NPZ was computed by averaging all z-scores and five existing algorithms for a diagnosis of HAND were applied. Change was defined as making a reliable change on the NPZ or a change in HAND category (impaired vs not). Results Change in NPZ over one year was more often in the direction of an improvement, and not different between HIV+ and HIV-individuals. Among the HIV+, the proportion meeting criteria for HAND at baseline ranged from 34-80% depending on the classification algorithm. A reliable change in NPZ was demonstrated in a single HIV+ participant. In contrast, a transition between HAND category at one year was common. Conclusion Among aviremic HIV+ older adults with a history of low nadir CD4 cell count, change in NPZ over 1 year was comparable to that seen among demographically matched HIV-individuals and did not represent a reliable change while transition across HAND category was common. Rates of HAND were very dependent on the classification algorithm applied. These findings provide some explanation for the inconsistent findings from existing studies and highlight the importance of exercising caution when pooling results in the field of neuroHIV.