Among individuals with HIV infection currently taking antiretroviral therapy (ART), self-administered preventive tuberculosis (TB) therapy with a 3-month course of rifapentine and isoniazid was found to be associated with a significantly increased rate of treatment completion compared with a 6-month course of isoniazid alone, according to results of a study published in Annals of Internal Medicine. Moreover, an additional round of short-course preventive therapy 1 year later provided no additional benefit nor did it decrease TB incidence in populations with high transmission and ART uptake.
Between November 2016 and November 2017, researchers conducted a parallel open-label randomized trial to compare the effects of 3 treatment regimens for the prevention of TB in participants with HIV infection currently taking ART. A total of 4014 patients in South Africa, Ethiopia, and Mozambique, who were aged 2 years and older without active TB, were included in the final analysis. Participants were randomly assigned to receive either weekly treatment with rifapentine and isoniazid for 3 months (given either once annually for 2 years or 1), or daily isoniazid alone for 6 months. Participants were screened for tuberculosis at baseline and months 3 and 12 for each year of the study, and chest x-rays and sputum cultures were obtained at months 12 and 24. The researchers used pill counts to assess the rate of treatment completion, and they measured TB incidence rates during a 24-month period.
Among the included in the analysis, the mean age was 41 years, 69.5% were women, and all were currently taking ART. Treatment completion rates after the first year were 90.4% (n=3610) among patients taking both rifapentine and isoniazid vs 50.5% (n=404) among those taking isoniazid alone (risk ratio, 1.78;95% CI, 1.61-1.95). The researchers found that incidence rates of TB between participants treated with a 3-month regimen of rifapentine and isoniazid once yearly for 1 year (n=1802) vs those treated with the same regimen once yearly for 2 years (n=1808) were similar (hazard ratio, 0.96; 95% CI, 0.61-1.50).
The study was limited by its pragmatic design and the potential inclusion of participants with active TB due to the use of an outdated TB screen (2011 World Health Organization 4-symptom screen) which had a sensitivity of 53%.
The researchers noted that “if rifapentine-isoniazid is effective in curing subclinical [TB], then intensive [TB] screening at month 12 may have [decreased] its effectiveness; however, it would not undermine the effectiveness of rifapentine-isoniazid in treating TB infection.”
Churchyard G, Cárdenas V, Chihota V, Mngadi K, et al. Annual tuberculosis preventive therapy for persons with hiv infection:A randomized trial. Ann Intern Med. Published online August 24, 2021. doi:10.7326/M20-7577