Background: AIDS Clinical Trial Group (ACTG) 5199, the International Neurological Study, aims to document the prevalence and incidence of neurological disease in HIV-infected patients in resource limited settings, and the effect of antiretroviral treatment on neurocognitive function. We present the baseline study data.

Methods: ACTG 5199 sites included:  Rio de Janeiro and Porto Alegre, Brazil; Chennai and Pune, India; Blantyre and Lilongwe, Malawi; Lima, Peru; Johannesburg and Durban, South Africa; Chiang Mai, Thailand; and Harare, Zimbabwe. At each site, a standardized neurological exam and a brief motor-based neuropsychological exam (timed gait, grooved pegboard, fingertapping, semantic verbal fluency) were administered at baseline prior to antiretroviral initiation. Staff were trained to standardize test administration.

Results: Of 860 subjects enrolled, 53% were female, 49% were black, median age was 34, median (Q1, Q3) CD4 was 172 (97, 232), and plasma viral load was 5.0 (4.5, 5.5) logs. Overall 113 (13%) had an abnormal neurologic examination. Examinations revealed a low prevalence of AIDS dementia (2 cases) and minor cognitive motor disorder (19 cases). However, 87 subjects were identified as having some evidence of peripheral neuropathy. As expected, there were significant differences across countries (p <0.001) on the neuropsychological tests after adjusting for CD4 and viral load.

Conclusions: In this first large global neurological study of antiretroviral treatment in resource-limited settings, there was a low prevalence of AIDS dementia and minor cognitive-motor disorder, while peripheral neuropathy was more common. In addition, there was significant variation in neurocognitive test performance across countries. These differences may reflect differences in populations, cultures, HIV subtypes , or variation in test administration. Longitudinal follow-up on antiretroviral treatment is underway.