Death outcome with successful treatment of tuberculosis patients

I read the previous publication on death outcome after successful treatment of smear‐positive tuberculosis (TB).[1] Moosazadeh et al. presented a cohort study in Iranian Registry Setting which concluded that the “Positive smear pulmonary TB even after successful treatment has an adverse effect on the patients’ survival and leads to a decrease in their survival rate in the long run.”[1] I agree with the cohort methodology and survivals’ data analysis of such an evidence. However, I am concerned about stratification[2] to analyze separately the effect of either diabetes, renal disease, cancer, previous TB treatment, or age group. I am wondering how the adjustable effects’ result after these variables are stratified with death status in different population settings.