QTc Interval Prolongation in Drug Resistant-Tuberculosis Patients Treated with Shorter Treatment Regimen

Abstract

Background: Shorter Treatment Regimen (STR) is a combination of treatments with a shortened period
from 20-24 months to 9-11 months. Shortened treatment requires a higher dose of drug to kill resistant
bacteria. Corrected QT (QTc) interval prolongation is one of the severe side effects of treatment.
Objective: This study aimed to find the factors of QTc prolongation in Drug Resistant-Tuberculosis (DRTB) patients treated with STR during an intensive phase.
Method: An analytical retrospective study was conducted at Dr. Soetomo General Academic Hospital,
Surabaya, Indonesia. DR-TB patients on the STR regimen were collected based on medical records between
September 2017 to August 2018. QTc interval was calculated by Fredericia formula. The relationship
between QTc interval at baseline and occurrence of QTc prolongation was analyzed using Chi-Square of
fisher’s exact test.
Results: Among 108 patients on the STR regimen, there were 20 (28%) patients experienced moderate
QTc prolongation (471-500 ms), and 31 (28%) patients had severe QTc prolongation (>500 ms) during four
months observation period in STR treatment. The prolonged QTc interval was significantly related to QTc
interval at baseline (p = 0.001). The QTc interval at baseline correlated significantly with the start time of
QTc prolongation (p < 0.001). Risk factors of age, gender, comorbid, hypertension, and potassium level at
baseline had a significant negative correlation to QTc prolongation.
Conclusion: The prolonged QTc interval was significantly related to QTc interval at baseline. The QTc
interval at baseline correlates significantly with the start time of QTc prolongation.