Higher prevalence of pulmonary tuberculosis revealed by Xpert MTB/RIF ultra among drug users in Kinshasa, Democratic Republic of Congo.

Abstract

Introduction: The Democratic Republic of Congo (DRC) is one of the eight countries with the highest burden of tuberculosis (TB) in the world. The public health system is inadequate and the screening for TB in the key and vulnerable population (KVP), including drug users (DU) is not currently done. The present study aimed to determine the prevalence of pulmonary TB among DU in Kinshasa by comparing molecular tests with microscopic techniques.

Methods: A cross-sectional study covering 22 townships (out of 24) of Kinshasa was conducted from October to December 2023. Sputum samples were collected from DUs aged ≥ 18 years, clinically suspected of TB, and attending drug consumption sites. The samples were analyzed by both the Acid-fast bacilli (AFB)-Nelseen hot staining and Xpert MTB/RIF Ultra for TB and rifampin-resistance diagnosis.

Results: For 399 DUs included in the study, the age range was from 18 to 77 years old, with a median of 31 (IQR: 25-39). Among these DUs, 359 (89%; 95% CI: 86.64- 92.55%) were male. TB prevalence was 3.5% (95% CI: 1.9-5.8%) when the AFB-Nelseen hot staining was used for diagnosis. However, the prevalence was significantly higher at 13.8% (95% CI: 10.6-17.6%) with the Xpert MTB/RIF test (p = 0.000). Xpert MTB-RIF Ultra contributed with an added value of 82% (95% IC: 79.25- 86.47%) to the diagnosis of TB in DUs. The KAPPA test showed a low concordance at 25%. Alcohol, diazepam and tobacco consumption have been identified as practical risks associated with the onset of pulmonary TB (p < 0.05).

Conclusion: DUs are a population at risk of TB that should not be neglected among all KVPs in Kinshasa. In this specific population, the determination of TB prevalence was significantly improved with the use of Xpert MTB/RIF Ultra compared to hot AFB-Neelsen staining. Among the DU included in the present study, those who habitually consumed alcohol in its different forms, diazepam for non-medical purposes, and tobacco, were significantly more infected than the others. DUs should be considered for systemic screening for pulmonary TB alongside other key populations such as people living with HIV and Xpert should be maintained as a first-line test instead of microscopy. Further studies also including asymptomatic participants are needed to assess the burden due to pulmonary TB in DUs as well as in their living environment.