Determining the risk factors associated with delayed sputum conversion at the end of the intensive phase among tuberculosis patients

Background: In pulmonary tuberculosis (PTB), the sputum conversion rate at 2 months is frequently used to evaluate treatment outcomes and effectiveness of a TB control programme.

Aims: The study aimed to estimate the rate of delayed sputum conversion and explore its predicting factors at the end of the intensive phase among smear-positive PTB (PTB +ve) patients.

Methods: A 3-year retrospective study was conducted in the government hospital in Pulau Pinang from 2016 to 2018. During the study, a standardized, data collection form was used to collect data from the patient record. Patients aged over 18 years were recruited. Multivariable logistic regression analysis was used to identify significant independent variables associated with delayed sputum conversion.

Results: A total 1128 of PTB patients were recorded visiting the TB clinic, 736 (65.2%) were diagnosed as PTB +ve; of these, 606 (82.3%) PTB +ve had a record of sputum conversion at the end of the intensive phase. Age ≥ 50 years, blue-collar jobs, smoking, heavy bacillary load, relapsed and treatment interrupted were significantly (P < 0.05) associated with delayed sputum conversion. Delayed sputum conversion rate at the end of the intensive phase was 30.5%.

Conclusion: The rate of sputum smear conversion in the intensive phase of treatment was independently associated with high sputum smear grading at diagnosis, relapsed and treatment interrupted categories, old age and blue-collar occupations.