Time for culture conversion and its associated factors in multidrug-resistant tuberculosis patients at a tertiary level hospital in Peshawar, Pakistan

Objectives: This study aimed to assess the time to sputum culture conversion (SCC) and its determinants among multidrug-resistant tuberculosis (MDR-TB) patients.

Methods: This cross-sectional study was conducted from January 2019 to January 2020. A total of 252 MDR-TB patients presenting at a tertiary level teaching hospital in Peshawar, Khyber Pakhtunkhwa (KP), were included. The patient’s demographic and clinical data were collected using a structured questionnaire. Time to SCC was calculated from the initiation of treatment till the patient had two consecutive negative cultures. The Cox proportional-hazards analysis was performed to check strength and association between the determinants and time for SCC.

Results: Out of 252 MDR-TB patients enrolled, sputum culture conversion was observed in 76.6% of the patients by the end of six months. While, 19.0% of the patients failed to achieve negative culture and remained positive after interim report of their treatment. Age > 45 years (HR = 15.22; 95% CI: 7.27-31.83; p<0.001), female gender (6.22; 2.90-13.36; p<0.001), BMI < 18.5 kg/m2 (10.28; 5.25-20.11; p<0.001), weight loss (0.03; 0.01-0.06; p<0.001), smoking (0.10; 0.05-0.21; p<0.001), diabetes mellitus (0.02; 0.00-0.04 p<0.001) and disease severity on chest X-ray (CXR) (0.03; 0.01-0.09; p<0.001) were the significant determinants of delayed sputum culture conversion.

Conclusion: MDR-TB patients with older age, low BMI, weight loss, diabetes, smokers and those with disease severity on CXR are less likely to respond to treatment as they displayed delayed SCC. Therefore, such patients should be meticulously followed up for successful management.