A meta-analysis of two phase 3 randomized controlled trials, TB-CHAMP and V-QUIN MDR, indicates that preventive treatment with levofloxacin may significantly reduce the incidence of multidrug-resistant tuberculosis (MDR-TB) among household contacts. The research, conducted in Vietnam and South Africa, suggests a potential new strategy for preventing the spread of this challenging disease, although further evaluation of risks and benefits is warranted.
The initial results of the TB-CHAMP trial, conducted at five sites in South Africa, showed that among 922 children with household exposure to MDR-TB, TB developed in 1.1% of the levofloxacin arm and 2.6% of the placebo arm (hazard ratio, 0.44; 95% CI, 0.15 to 1.25) by week 48. Similarly, the V-QUIN MDR trial, which enrolled 2,041 children and adults across ten sites in Vietnam, reported confirmed TB in 0.6% of the levofloxacin group and 1.1% of the placebo group (incidence rate ratio, 0.55; 95% CI, 0.19 to 1.62) within 30 months. However, neither trial demonstrated statistical significance individually.
Meta-Analysis Reveals Significant Reduction
Combining the data from both trials in a meta-analysis, researchers found a more pronounced effect. Among participants in the levofloxacin group, 8 developed TB compared to 21 in the placebo group, representing a relative difference in cumulative incidence of 0.41 (95% CI, 0.18 to 0.92). This suggests that levofloxacin was associated with a 60% relative reduction in TB incidence.
"These results suggest that MDR-TB preventive treatment with levofloxacin was associated with a 60% relative reduction in TB incidence among adults and children but was associated with increased low-grade adverse events (particularly musculoskeletal)," the researchers wrote in NEJM Evidence.
Safety Considerations
While the meta-analysis indicated a significant reduction in TB incidence, it also highlighted an increased risk of musculoskeletal events. The analysis revealed that musculoskeletal events of any grade occurred more frequently in the levofloxacin group (risk ratio, 6.36; 95% CI, 4.30 to 9.42). This finding underscores the importance of carefully weighing the benefits and risks of levofloxacin preventive treatment.
WHO Recommendations
Based on the data from TB-CHAMP, V-QUIN MDR, and other observational studies, the World Health Organization (WHO) updated its recommendations for TB preventive treatment (TPT) in September. The WHO now strongly recommends 6 months of daily levofloxacin in contacts exposed to MDR or rifampicin-resistant TB.
"The strong recommendation reflects the GDG opinion that the benefits of levofloxacin outweigh the potential harm in most people who are eligible to receive it," the WHO stated. The organization emphasized the need for strict eligibility criteria, maximizing treatment completion, and ensuring follow-up care for all contacts, regardless of TPT completion.
Implications for MDR-TB Prevention
The findings from these trials and the subsequent meta-analysis offer a promising avenue for preventing MDR-TB, which affects an estimated 400,000 people globally each year. Given the challenges associated with treating MDR-TB, preventive strategies are crucial for reducing the global burden of the disease. However, further research is needed to optimize the use of levofloxacin and to identify strategies for mitigating potential adverse events.
