Experience in children
In the related study, reported by lead author Thierno Diallo, MD, of Hôpital National Ignace Deen, in Conakry, Guinea, along with Dr. Menzies, and their coauthors, 829 children were randomized to 4 months of rifampin or 9 months of isoniazid.
The study population included 79 children under 2 years, the age group that has the highest risk of life-threatening TB, Dr. Diallo and his colleagues wrote in their report.
Treatment was completed in 86.5% of all children randomized to rifampin, compared with 77.1% in the isoniazid arm (difference of 13.6 percentage points; 95% confidence interval, 7.9-19.3; P less than .001), according to the investigators.
Two active tuberculosis cases were diagnosed in the isoniazid group over 542 person-years of follow-up, versus no cases in the rifampin group over a similar follow-up period.
“Although the only cases of active tuberculosis were diagnosed in the isoniazid group, we cannot conclude that 4 months of rifampin was either superior or noninferior to 9 months of isoniazid for the prevention of active tuberculosis,” the authors wrote.
“However, since there were no cases of active tuberculosis in the rifampin group in our trial or among 434 children who received 3 months of once-weekly isoniazid plus rifapentine in another trial, we suggest that these shorter rifamycin containing regimens are effective,” they added.
In contrast to the adult trial, safety profiles in this study were similar for rifampin and isoniazid, investigators said.
The lack of difference is side effects was possibly because of the differences in the pharmacokinetic activity of rifampin in younger patients, a topic that deserves further study, they concluded.
No potential conflicts of interest relevant to the studies were reported by Dr. Menzies, Dr. Diallo, or their coauthors.
Both studies were supported by grants from the Canadian Institutes of Health Research. The adult study was supported in part by a grant from the Australian National Health and Medical Research Council, while the companion study in children was supported in part by a grant from the Conselho Nacional de Pesquisa in Brazil.
SOURCES: Menzies D et al. N Engl J Med. 2018 Aug 2;379(5):440-53; Diallo T et al. N Engl J Med. 2018 Aug 2;379(5):454-63.