DOI: 10.5061/dryad.8gtht76rt
title: Effect of six- versus eight-month regimen on treatment success and smear conversion among retreatment patients

description: Background: In 2017, the regimen for patients with retreatment
 tuberculosis (TB) changed from an eight-month treatment regimen that
 consisted of Isoniazid, Rifampicin, Pyrazinamide, Ethambutol, and
 Streptomycin (2RHZES/1RHZE/5RHE) to a six-month treatment regimen
 (2RHZE/4RH). Currently, there is uncertainty regarding the effect of the
 six-month treatment regimen on treatment outcomes across TB Control
 Programs. We evaluated the effect of the six-month treatment regimen on
 treatment success rate (TSR) and sputum smear conversion (SSC) among
 patients with retreatment pulmonary bacteriologically confirmed TB
 (PBC-TB) in Kampala, Uganda. Methods: Between November 2021 and February
 2022, we abstracted data for patients with retreatment PBC-TB who had
 received treatment between January 2012 and July 2021 across six large TB
 clinics in Kampala, Uganda. The primary outcome was TSR defined as cure or
 treatment completed. The secondary outcome was SSC defined as a change in
 sputum smear test result from positive to negative. We applied
 doubly-robust regression estimation for causal effect analysis, with TSR
 as the primary outcome and SSC at 2/3, 5, and 6/8 months as secondary
 outcomes. We reported average causal effects using marginal odds ratios
 (MOR) and 95% confidence intervals (CI). Results: We analyzed data for 427
 participants with an overall mean age of 34.6±10.8 years. Over half
 (53.9%) of the participants were treated with a six-month treatment
 regimen. TSR was 49.6% overall, and higher in the six-month regimen group
 (52.2%) than in the eight-month regimen group (46.7%). The six-month
 treatment regimen significantly improved the TSR compared to the
 eight-month treatment regimen (MOR, 1.27; 95% CI, 1.06-1.52). However, the
 effect of the six-month treatment regimen on SSC at (MOR, 1.01; 95% CI,
 0.91-1.12), 5 months (MOR, 0.96; 95% CI, 0.88-1.04), and 6/8 months (MOR,
 0.83; 95% CI, 0.19-3.51) is similar to the eight-month treatment regimen.
 Conclusion: The six-month treatment regimen results in a better TSR among
 patients with retreatment PBC-TB compared to the eight-month treatment
 regimen. Therefore, patients with retreatment PBC- TB who do not have
 rifampicin resistance should continue to receive the six-month treatment
 regimen.
description: We abstracted data from the TB unit register between November
 2021 and February 2022 for all patients with retreatment PBC-TB with known
 rifampicin resistance status for the period January 2012 to December 2021.
 We used a standardized data abstraction tool in KoBo ToolBox, a web-based
 and smartphone data collection tool. KoBo ToolBox was integrated with
 quality control measures such as skip patterns, alerts, range, and legal
 values to ensure accuracy in data entry. The data were collected by
 trained and supervised research assistants, one per study site. On each
 day, we downloaded the data from the server, performed data queries, and
 provided feedback to the research assistants to improve data
 accuracy.
description: Stata version 15 onwards.