We did not perform routine HIV testing in our patient cohort and it is possible that over-representation of HIV seropositivity in our active TB group may have had a confounding effect. We believe this is unlikely in view of the low prevalence of HIV coinfection among TB patients in Peru (,5%) found in previous studies [17] . Important areas of future study will be to establish the applicability of this approach in the contexts of TB-HIV coinfection and smear-negative TB.