CD4 and tuberculosis: Patients who started second-line ART with advanced WHO stage (stage IV) had 3.6 times (AHR = 3.63, 95% CI = 1.72–7.67) higher likelihood of treatment failure compared to patients who started second-line ART at early WHO stages (stage I or II) keeping the other variables (age, TB status, CD4 count, adherence) constant.