Isoniazid preventive therapy safe, effective against TB in pregnant women with HIV

Isoniazid preventive therapy (IPT) is safe to use in pregnant women with HIV, especially those with a CD4 count <350 cells/μl, conferring protection against incident tuberculosis (TB) without deleterious maternal and foetal consequences, a study has shown.

Researchers looked at the medical records of a cohort of pregnant women living with HIV (n=43,971; mean age, 29.8 years) and who had received antiretroviral therapy prior to and/or during the index pregnancy. IPT was dispensed to 16.6 percent of the population at some point after conception. Median duration of IPT was 168 days, while median duration of antenatal exposure was 124 days.

Compared with those who did not receive IPT, women on IPT had lower odds of experiencing poor pregnancy outcomes (adjusted odds ratio [aOR], 0.83, 95 percent confidence interval [CI], 0.78–0.87).

The beneficial effect on pregnancy outcomes was notably pronounced when IPT was initiated after the first trimester (aOR, 0.71, 95 percent CI, 0.65–0.79) or during the first trimester (aOR, 0.64, 95 percent CI, 0.55–0.75).

IPT cut the risk of TB by about 30 percent (adjusted hazard ratio [aHR], 0.71, 95 percent CI, 0.63–0.81; absolute risk-difference, 1,518/100,000 women). The effect was modified by CD4 count, such that the protective effect was greater if CD4 count was ≤350 cells/μl (aHR, 0.51, 95 percent CI, 0.41–0.63) than if the count was >350 cells/µl (aHR, 0.93, 95 percent CI, 0.76–1.13).

The findings indicate that antenatal IPT provides protection against TB up to 12 months postpartum, according to the researchers. The strategy also appears to be safe, even reducing the risk of poor pregnancy outcomes such as miscarriage, stillbirth and low birthweight, among others.