A major international study found that replacing two medications in the traditional protocol with newer agents (high-dose rifapentine and moxifloxacin) can reduce tuberculosis treatment time from six months to four months in people who do not have drug resistance.

A long-term scientific aim has been to shorten the length of tuberculosis (TB) therapy. The time needed to treat tuberculosis has not decreased since the 1980s, and it took more than 20 years to perform the high-dose rifapentine and moxifloxacin trials that led to the eventual design of Study 31.

Reduced duration of medication will increase adherence while still saving money for the healthcare system and patients with tuberculosis. It will, in fact, allow for faster completion of specifically experienced therapy and allow people with TB to return to work sooner, reducing the household effects of TB.

The study

At 34 sites in 13 countries across Asia, the Americas, Africa, and Europe, people with newly diagnosed culture-positive and drug-susceptible pulmonary tuberculosis were recruited for the international research. People with HIV who had a CD4 cell count of more than 100 were entitled to participate in the study.

The 2516 participants in the sample were assigned to one of three regimens at random.

1. Eight weeks of daily rifampicin, isoniazid, pyrazinamide, and ethambutol therapy, followed by 18 weeks of daily rifampicin and isoniazid treatment (standard treatment).
2. Eight weeks of high-dose rifapentine (1200 mg), isoniazid, pyrazinamide, and ethambutol daily therapy, followed by nine weeks of rifapentine and isoniazid daily treatment. As the basis of the 4-month procedure, rifapentine is used instead of rifampicin in this protocol (RPT).
3. Eight weeks of daily high-dose rifapentine (1200 mg), isoniazid, pyrazinamide, and moxifloxacin therapy, followed by nine weeks of daily high-dose rifapentine, isoniazid, and moxifloxacin treatment. As the basis of the 4-month procedure, rifapentine is used instead of rifampicin, and moxifloxacin is used instead of ethambutol (RPT-MOX).

The primary outcome study involved 2,343 people who were randomly assigned, who had drug-susceptible tuberculosis. The primary outcome was TB-free survival at 12 months. The absence of cure was described as an unfavourable outcome.

The study discovered no statistically meaningful disparity in unfavourable result between the control group (14.6%) and the RPT-MOX group (15.5%), indicating that the RPT-MOX protocol fulfilled the statistical criterion for non-inferiority and was just as successful as standard care.