Limitations of the international HIV dementia scale in the current era

Background: The International HIV Dementia Scale (IHDS) was developed as a tool for HIV dementia in both the industrialized and developing world. As initially described, a cut-point of 10 on this 12-point scale had sensitivity of 80% with specificity of 55% in Uganda. Recent publications from Uganda identify very high rates of probable HIV dementia (64%, BMC Psychiatry 2013) using this screening instrument, prompting us to examine performance characteristics for the current era. Methods: 2414 individuals from East Africa underwent testing with the IHDS and a 30-minute cognitive battery that included the World Health Organization (WHO) auditory verbal learning test (AVLT) trial 1, sum of 1-5, and recall; the Trails A test; the grooved pegboard test; and action fluency task. We defined impairment among HIV+ participants as - 1 SD on two tests or - 2 SD on one test when performance was compared to concurrently enrolled controls stratified by age (=35) and education (<6 years, 6-12 years, >12 years). We examined predictive capacity of the IHDS using receiver operator characteristic (ROC) curve. Psychometrists underwent initial certification with re-certification every 6 months. Results: We enrolled participants from Uganda (n=531), Kenya (n=1466) and Tanzania (n=417) with mean (SD) age for HIV+ (n=2009) and HIV-negative (n=405) groups: 39.8 (10.8) and 37.6 (10.5), respectively (p=0.006). Among HIV+, 1651 (67%) were on cART, 979 (51%) had plasma viral loads <50 copies/ml and 702 (36%) met criteria for impairment. The mean (SD) IHDS score was 8.5 (1.7) and 9.0 (1.6) for HIV+ and HIV-negative, respectively (p=0.001). Using the cut-point of 10, 1290 (64%) of HIV+ subjects would be classified as having dementia as well as 215 (53%) of HIV negative controls. The ROC area under the curve (AUC) was maximally 60% offering a sensitivity of 66% and specificity of 66% at a cut point of 9 among HIV+. Conclusion: The IHDS has poor performance characteristics for the identification of impairment in East Africa in the current era. Performance for the most severe form of impairment, HIV Dementia, typically constituting < 5% of patients with access to cART, cannot be assessed from these data. Our data raise concerns for continued use of the IHDS in the era of cART. (Figure Presented).