Evaluating the Safety of Immediate Versus Deferred Isoniazid Preventive Therapy Among HIV-Infected Pregnant Women

Tuberculosis (TB) is a leading cause of death among HIV-infected persons in low-income settings and can be a serious complication for HIV-infected pregnant women and their infants. Isoniazid (INH) preventive therapy (IPT) is effective in preventing TB infection in HIV-infected adults, but the safety of IPT in pregnant women is unknown. This study evaluated the safety of IPT among HIV-infected pregnant women.

TB disease is the most common HIV-related opportunistic infection and is a leading cause of death among HIV-infected persons in low-income settings. When TB occurs during or soon after pregnancy, it can cause complications for the mother as well as infant TB or death. Infant TB is very difficult to diagnose, and up to half of infant TB cases are caused by maternal TB. It has been shown that treatment for active TB is safe and effective during pregnancy and that IPT is safe and effective in preventing TB infection in HIV-infected adults. However, the safety of IPT in HIV-infected pregnant women is not known, especially in regard to its combination with highly active retroviral therapy (HAART). This study evaluated the safety of immediate (antepartum, or before delivery) versus deferred (postpartum, or after delivery) IPT among HIV-infected pregnant women in high TB incidence settings.

HIV-infected pregnant women were randomly assigned (1:1) to one of two arms: Arm A (immediate/antepartum INH) and Arm B (deferred/postpartum INH group). Women in both arms received oral prenatal multivitamins and pyridoxine (vitamin B6) once daily from study entry through Week 40 postpartum.

Study visits for women occurred at screening, entry, every 4 weeks until labor and delivery, at labor and delivery, and every 4 weeks after delivery until 48 weeks postpartum. Visits consisted of giving a medical history and undergoing a physical exam and blood collection; all visits through the delivery visit also included an obstetrical exam. Presence of HIV infection was documented at screening and a tuberculin skin test (TST) was administered at the delivery visit and at the Week 44 postpartum visit. Study visits for infants occurred at birth and at several time points through Week 48. These visits included a medical history, physical exam, and blood collection. Intensive pharmacokinetic (PK) samples, that is, samples taken at many different time points within a 24-hour test period, were collected from a small subset of women, one test period at antepartum and one at postpartum. Sparse PK samples, that is, samples taken at fewer time points within the test period, were collected on all women, once each at antepartum and postpartum.