In a multivariate Cox model that adjusted for age, CD4+ count > or < 250/mm3 and hemoglobin level, the presence of hepatitis B or C remained significantly associated with the development of liver toxicity of any grade (hazard ratio [HR]: 1.797, 95% CI 1.042-3.098, P = 0.035) (Table 2). This evidence concerns the gene CD4 and hepatitis B virus infection.