Differential effects of low WBC counts on HIV disease course in HIV-infected EA and AA. KM plots depict survival curves computed according to race/ethnicity and average WBC count in the entire cohort (A), and HIV⁺ subjects categorized as seroconverter (B), and seroprevalent (C). RH indicates relative hazards (reference RH = 1 represents AAs with WBC counts ≥ 4000 cells/mm³); CI, confidence interval; P, significance values obtained by Cox proportional hazards modeling; and n, number of subjects.