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Research Article

Low body mass index as a predictor of sputum culture conversion and treatment outcomes among patients receiving treatment for multidrug-resistant tuberculosis in Lesotho

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Article: 2305930 | Received 03 Jun 2023, Accepted 11 Jan 2024, Published online: 02 Feb 2024
 

ABSTRACT

Background

A low body mass index (BMI) at the start of treatment for rifampicin- or multidrug-resistant tuberculosis (MDR/RR-TB) is associated with poor treatment outcomes and may contribute to delayed sputum culture conversion, thereby prolonging the period of potential transmission to others. Whether the relative importance of low BMI in predicting treatment outcomes differs by HIV status is unclear.

Objectives

We evaluated the association between low BMI and two dependent variables, sputum culture conversion and end-of-treatment outcome, among patients receiving treatment for MDR/RR-TB in Lesotho, a setting with a high prevalence of HIV infection.

Methods

Secondary data from a prospective cohort of patients initiating a longer (18–20 months) treatment containing bedaquiline and/or delamanid under routine programmatic conditions in Lesotho were analysed. Risk ratios and differences were adjusted for potential confounders using multivariable logistic regression, and estimates were stratified by HIV status.

Results

Of 264 patients, 105 and 250 were eligible for culture conversion and end-of-treatment analyses, respectively. Seventy-one per cent of patients (74/105) experienced culture conversion within six months, while 74% (184/250) experienced a favourable end-of-treatment outcome. Low BMI was associated with a lower frequency of culture conversion at six months among those who were not living with HIV (relative risk [RR]: 0.50 [95% CI: 0.21, 0.79]); this association was attenuated among those living with HIV (RR: 0.88 [95% CI: 0.68, 1.23]). A low BMI was moderately associated with a lower frequency of treatment success (RR = 0.89 [95% CI: 0.77, 1.03]), regardless of HIV status.

Conclusions

Low BMI was common and associated with the frequency of six-month culture conversion and end-of-treatment outcomes. The association with culture conversion was more pronounced among those not living with HIV. Addressing the myriad factors that drive low BMI in this setting could hasten culture conversion and improve end-of-treatment outcomes. This will require a multipronged approach focused on alleviating food insecurity and enabling prompt diagnosis and treatment of HIV and TB.

Responsible Editor Jennifer Stewart Williams

Responsible Editor Jennifer Stewart Williams

Acknowledgments

We acknowledge and thank our funder, Unitaid, for financing the endTB project, including the observational study. Great appreciation to all the patients who participated in the endTB observational study and to the clinicians and programme staff at Partners In Health (PIH), Lesotho as well as the Lesotho National Tuberculosis and Leprosy Program (NTLP) for all your efforts in ending TB. We thank endTB staff at Partners In Health (PIH), Médecins Sans Frontières (MSF), Epicentre, and Interactive Research and Development (IRD) for making this project a success. We thank Marguerite Curtis and Alyson Nunez for their administrative support for this publication.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

The manuscript was conceived by L.O., B.O., C.M., L.M., M.M., and M.F. C.Z. conducted analyses with contributions by B.O. Study design was done by all authors, and first draft was written by L.O. with support from M.F. All authors interpreted study results and approved the final version.

Paper context

A low BMI at the start of treatment for rifampicin- or multidrug-resistant tuberculosis (MDR/RR-TB) is associated with poor treatment outcomes and may contribute to late sputum culture conversion, thereby prolonging the period of potential transmission to others. Whether the relative importance of low BMI in predicting treatment outcomes differs by HIV status is unclear. Given the synergistic epidemics of tuberculosis, HIV, food insecurity, and poverty in Lesotho, low BMI may constitute a particularly important warning sign for patients who present to care for MDR/RR-TB. Among patients treated for MDR/RR-TB with a longer regimen containing bedaquiline and/or delamanid, we examined whether a low BMI predicted culture conversion within six months of treatment or end-of-treatment success and whether these relationships were modified by HIV status.

Ethics and Consent

The endTB Observational Study protocol was approved by central ethics review committees for each consortium partner, and local ethical approval was obtained in all endTB countries. Participants provided written informed consent for inclusion in the observational cohort.

Additional information regarding study methods, including eligibility criteria, definitions, and statistical analyses, can be found in the online supplement.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by Unitaid.