Reliability and validity of self-reported CD4 lymphocyte count and viral load test results in people living with HIV/AIDS.

Self-reporting is a common, convenient, and inexpensive method for collecting health status information in HIV/AIDS research, but the reliability and validity of these data remain suspect. HIV-positive persons (n=174) completed self-report measures of demographics, health status, and health literacy, and provided permission to collect CD4 cell counts and viral load results from provider charts. Clinically meaningful categories of CD4 cell counts were reliably and validly assessed using self-report measures. Self-reported viral load, however, demonstrated only marginally acceptable reliability and validity, with the greatest validity occurring for recall of undetectable viral load. Self-reported health status was most reliable and valid for persons with higher levels of education and literacy. CD4 cell counts can therefore be reliably and validly assessed through self-reporting, particularly when collected in clinically meaningful units from persons with higher education. Self-reported viral load should be interpreted with caution and is most reliable when dichotomized into detectable/undetectable categories.