Effect of a shortened anti-TB regimen on treatment success in Kampala, Uganda

Study Context

Previously treated tuberculosis (TB) patients comprise 10-20% of the annual global TB cases and have a high risk of mortality and drug resistance. They are also more likely to not achieve successful treatment compared to patients with new TB diagnoses. In 2017, the World Health Organization (WHO) recommended the use of a six-month anti-TB regimen in treating patients with retreatment TB, provided there is no resistance to rifampicin and isoniazid. Although Uganda adopted the use of the six-month anti-TB regimen in August 2017, no studies have evaluated the effect of this treatment regimen on outcomes among retreatment TB cases.

The aim of this quasi-experimental study is to examine the effect of the six- versus the eight-month anti-TB regimen on treatment success among retreatment TB patients in six public health facilities in Kampala, Uganda. Findings from this study will shape TB clinical practice, programming, and public health interventions in Uganda and similar settings.

Study Design

The study will use retrospectively collected data to identify and categorize participants into intervention (six-month anti-TB regimen) and comparison (eight-month anti-TB regimen) groups. KoBo ToolBox, a web-based, smartphone data collection tool will be used to retrospectively abstract data from the TB unit registers from the period of January 2012 to December 2021.

The primary outcome will be treatment success, measured on a binary scale following the WHO standard definitions. Patients who were cured of TB or who had completed treatment will be considered successfully treated, whereas those who failed treatment, got lost to follow-up, or died will be considered unsuccessfully treated. The secondary outcome will be sputum smear conversion at two months of TB treatment, restricted to patients with bacteriologically confirmed TB.

The covariates of interest will include the following: age in years, sex (male or female), level of health facility, type of TB disease, HIV status), baseline weight in kilograms, baseline bacilli load, baseline rifampicin resistance profile, treatment delivery model, and treatment supporter availability.

Results and Policy Lessons

Researchers found that the six-month regimen led to higher treatment success and sputum smear conversion rates compared to the eight-month regimen. The treatment success rate was 49.6% overall, 52.2% for people with TB treated with the six-month regimen compared to 46.7% for those treated with the eight-month regimen.

The findings have important policy implications for TB treatment in low and middle-income countries, suggesting that shortening the duration of treatment can improve outcomes. Findings have been shared with the Office of the Director Public Health and Environment, Kampala Capital City Authority, including customized messages for patient health education at the respective study sites.