Discriminant validity of the Medical Outcomes Study cognitive function scale in HIV disease patients

Human immunodeficiency virus (HIV) infection results in a chronic course of disease progression and eventual death. With this disease progression comes decreases in health-related quality of life and cognitive function in many patients. We evaluated the construct and discriminant validity of the Medical Outcomes Study four-item and six-item cognitive function scale in a sample of 162 patients with HIV disease. The patients were assessed at baseline and after 4 months with the cognitive function scale, a cognitive functioning transition item, the Reitan trail making test (TMT) and the Centers for Epidemiologic Studies Depression (CES-D) scale. The results found that the four- and six-item cognitive function scales varied by HIV disease stage, CD4 count, self-reported change in cognitive function, TMT-based cognitive impairment and depression. The differences in the cognitive function scores were attenuated, but still remained statistically significant even after controlling for depression. The cognitive function scales predict cognitive impairment based on the TMT. The results support the construct validity of these self-report cognitive function scales.