Correlation of Procalcitonin with Acid Fast Bacilli and Gene Xpert MTB/RIF as a Marker of Treatment Progress in Pulmonary Tuberculosis patients

Abstract

There are several limitations in using AFB and GeneXpert to evaluate the treatment of TB patients, one of which is influenced by sputum quality. Therefore, an alternative method is needed to help evaluate the treatment of TB patients. This study aimed to analyze the correlation of the Procalcitonin test with AFB and GeneXpert for evaluating the treatment of TB patients and the performance of Procalcitonin as a marker of TB patient treatment progress. A prospective cohort study was conducted from May to September 2022 at the West Nusa Tenggara General Hospital, Indonesia. Sputum and blood samples were collected from 36 patients who were confirmed positive for TB by GeneXpert MTB/RIF examination, then examined for procalcitonin and AFB before being given treatment and after the intensive phase of treatment. Procalcitonin tested with VIDAS Biomerieux and VIDAS BRAHMS PCT kit. Procalcitonin did not correlate with AFB (p=0.064, r= 0.327) and GeneXpert before treatment (p=0.169, r=0.245), but correlated with AFB (p=0.013, r=0.427) and GeneXpert MTB/RIF (p=0.020, r=0.405) after the intensive phase of treatment. Procalcitonin test with a cut-off value of 0.07 detected negative AFB cases after treatment with a sensitivity of 28.6 and a specificity of 96.2%. The procalcitonin cut-off value of 0.07 also detected negative Xpert MTB/RIF after treatment with a sensitivity of 16.7% and a specificity of 100%. The performance of Procalcitonin for detecting negative smear and negative Xpert MTB/RIF after the intensive phase of treatment is classified as having high specificity, but its sensitivity is still low. Future studies are needed to evaluate the performance of Procalcitonin compared to bacterial cultures.