Lower hemoglobin levels in human immunodeficiency virus–infected patients with a positive direct antiglobulin test (DAT): relationship with DAT strength and clinical stages

BACKGROUND: There are conflicting opinions regarding the effect of positive direct antiglobulin test (DAT) on hemoglobin (Hb) levels in human immunodeficiency virus–infected (HIV+) patients. STUDY DESIGN AND METHODS: A total of 166 samples from HIV+ outpatients were studied. The DAT was performed with the tube test and column agglutination technology (CAT). RESULTS: The DAT was positive in 18.67 percent with the tube method and 33.73 percent with the CAT. Patients with DAT‐positive results showed lower Hb levels than DAT‐negative patients, 12.3 g per dL versus 14.3 g per dL (p = 0.0002). The univariate logistic regression enabled us to study the phenomenon better and fit the probability of having a DAT‐positive result on the basis of the Hb levels. The relationship between the CAT and the tube test when washing the red blood cells (RBC) at 4°C was stronger than when washing these at room temperature (φ = 0.8156; p = 0.000). The Hb levels were significantly lower in the positive DATs of Stage C (acquired immune deficiency syndrome [AIDS]) and Stage B (symptomatic non‐AIDS patients), which showed decreasing Hb values for increasing agglutination strengths (p = 0.000). Anemia was related with the DAT results (odds ratio [OR], 8.005; p = 0.000) but not to the AIDS condition (OR, 1.741; p = 0.221). DISCUSSION: Our study indicates that the DAT‐positive results may be specifically related to lower Hb levels in HIV+ patients. The immunologic RBC clearance could be part of the anemic multifactorial condition in HIV+ patients.