Normal Dose Moxifloxacin Maintained Effectiveness in Rifampin-Resistant TB

A short, 9-month regimen of normal-dose moxifloxacin maintained good effectiveness up to 24 months after the cessation of therapy in patients with rifampicin-resistant tuberculosis (RR-TB), according to the results of an observational cohort study published in EClinicalMedicine.

Recognizing that outcomes with the short treatment regimen in patients with RR-TB have not been well established and that sparse data are available on the frequency of relapse after treatment completion, investigators sought to report on outcomes 2 years after the completion of therapy in patients from 9 African countries: Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Côte d’Ivoire, Democratic Republic of Congo, Niger, and Rwanda.

A total of 1006 patients who were treated with the 9-month regimen were followed every 6 months via the use of sputum cultures, which were obtained for up to 24 months after completion of treatment. Cox proportional hazard models were used to analyze the risk for any unfavorable outcome, the risk for failure and relapse, and the risk for death both during and after treatment, based on patient characteristics and initial drug susceptibility.

Results showed that of the 1006 participants, 823 were evaluated for treatment success at the conclusion of therapy. After treatment completion, 67.8% (558 of 823) of patients had ≥1 culture result available at ≥6 months of posttreatment follow-up, 57.2% (471 of 823) of participants at ≥12 months, 32.1% (264 of 823) at ≥18 months, and 19.4% (160 of 823) at ≥24 months. The median duration of follow-up was 15.9 months (range, 0.2-36.6 months; mean, 16.5 months) in the 558 patients with ≥1 culture result available at follow-up.

Relapse-free treatment success was 79.3% in the entire cohort. After stratification by HIV status, the success rate was 80.9% in patients who were HIV negative and 72.5% in patients who were HIV positive. A total of 14 patients met the definition of a relapse, with a median interval between treatment completion and relapse of 8.3 months (range, 3.6-21.1 months). The researchers noted that in the presence of initial resistance to fluoroquinolones or to isoniazid, the probability of relapse-free success decreased and the risk for failure or relapse increased.

The proportion of participants with available follow-up culture results did not differ significantly according to patient age, sex, body mass index, HIV status, and extent of lung lesions. In contrast, the percentage of patients with follow-up culture results available did differ widely based on the country of enrollment, ranging from 48.3% in Côte d’Ivoire to 96.4% in Burundi. Reasons for lack of available culture results in 265 participants at follow-up included death (19.2%), refusal to attend or provide sputum results (21.9%), and inability to be located (58.9%).

The investigators concluded that the results from this study reinforce the World Health Organization’s recommendation to use this short, 9-month regimen in patients with RR-TB who are likely to be resistant to the newest generation of fluoroquinolones. Additional research is warranted to improve the tolerance of this treatment regimen, in particular by exploring the use of a short, all-oral regimen without a second-line injectable agent.

Reference

Schwœbel V, Trébucq A, Kashongwe Z, et al. Outcomes of a nine-month regimen for rifampicin-resistant tuberculosis up to 24 months after treatment completion in nine African countries [published online February 10, 2020]. EClinicalMedicine. doi:10.1016/j.eclinm.2020.100268