Rifampicin-resistant tuberculosis in Nangarhar, Afghanistan: prevalence and risk factors
Abstract
Afghanistan bears a high burden of tuberculosis (TB). Rifampin-resistant TB (RR-TB) poses a serious threat to disease control, and province-level data remain limited. This study aimed to identify associated risk factors and estimate the prevalence of Rifampin-Resistant TB among adult in Nangarhar Province. We conducted an observational study with two components, facility based cross-sectional study to estimate the prevalence of rifampin-resistant TB, with a case–control analysis to evaluate associated risk factors, at three TB centers in Nangarhar province, from 1 September 2023 to 27 June 2024. A cross-sectional study estimated the prevalence of Rifampin-resistant TB among adults with Xpert-confirmed TB. A case–control analysis evaluated associated risk factors compared rifampicin-resistant TB cases with rifampicin-susceptible controls selected from the same centers. Eligibility and classification were determined by laboratory testing, including Xpert MTB/RIF, culture, and phenotypic drug susceptibility testing; clinical assessment and structured interviews were subsequently conducted. Multivariable logistic regression was used to identify independent risk factors for RR-TB. The prevalence of rifampicin-resistant TB was 3.3% (67/2,038; 95% CI: 2.6–4.2). Prevalence was higher among previously treated patients than among new patients (30/273, 11.0%; 95% CI: 7.6–15.4 vs. 37/1,765, 2.1%; 95% CI: 1.5–2.8). Independent predictors of rifampicin resistance included prior TB treatment (aOR 4.0, 95% CI 1.5–10.7), household crowding (family size 5–10: aOR 5.1, 95% CI 2-12.6); sleeping density ≥ 4 persons/room: (aOR 20.8, 95% CI 2.67–162.8), TB exposure (any contact: aOR 15, 95% CI 3.2–69.6); exposure > 6 months: aOR 27.0, 95% CI 5-157), and smear positivity (aOR 2.5, 95% CI 1.2–5.15). Among the 60 RR TB cases with phenotypic results, 57/60 (95%) also had isoniazid resistance, and 10/60 (17%) had fluoroquinolone resistance. RR-TB in Nangarhar is concentrated among retreatment patients and crowded households. The findings highlight the importance of universal rapid drug susceptibility testing, adherence support, and household-centred contact investigation in this setting. Clinical trial number not applicable.