CD4 and tuberculosis: Despite the fact that the majority of studies found no significant association between low CD4 levels (< 200 cells/mm3) and tuberculosis occurrence, the pooled effect size revealed that low CD4 levels (< 200 cells/mm3) were a risk factor for tuberculosis occurrence (AHR = 1.23, 95% CI: 1.1, 1.35) with no evidence of heterogeneity between studies (p = 0.7) (Fig. 6).