The results of a phase 4 randomized controlled trial indicate shortened regimens of preventive tuberculosis (TB) therapy are safe and effective options for preventing active TB infections, US and Brazilian researchers reported yesterday in PLOS Medicine.
The trial, conducted in Rio de Janeiro and Manaus, assigned 500 people age 15 and older without HIV who had household or occupational exposure to individuals with confirmed TB infection to receive either one or three months of isoniazid and rifapentine (HP; 1HP or 3HP).
Both regimens have been found in previous trials to be effective at preventing active TB infection and are significantly shorter than the standard regimen (six to nine months of isoniazid), which has been the mainstay of TB preventive therapy (TPT) for decades but has had "abysmal" uptake and poor completion rates. But some data gaps remain.
"The availability of two innovative short-course TPT regimens offers a transformative opportunity for global tuberculosis control and achieving the End TB targets," the study authors wrote. "However, the safety of the 1HP regimen in people without HIV infection has not been thoroughly evaluated, and the relative acceptability of 1HP versus 3HP is unknown."
High completion rates in both groups
The primary outcomes of the trial were successful completion of more than 90% of medication in the regimens and safety.
Both treatment regimens had high completion rates—89.6% in 1HP recipients and 84.1% in the 3HP group. Adverse reactions were mostly mild or moderate, with targeted safety events or treatment discontinuation because of side effects occurring in 16.1% of patients in the 1HP group and 10.4% in the 3HP arm. Neither regimen was considered superior to the other.
The study authors say the results provide clinicians, public health officials, and patients with the data needed to make informed choices about which regimens to use and could help Brazil and other high TB-burden countries achieve TB control.
“Preventing TB with short courses of well-tolerated medicines ensures that millions more people around the world can be protected from the devastating consequences of TB disease,” coauthor Marcelo Cordeiro-Santos, MD, PhD, said in a journal press release.