A Randomized Controlled Trial of Isoniazid to Prevent Mycobacterium tuberculosis Infection in Kenyan Human Immunodeficiency Virus-Exposed Uninfected Infants

Isoniazid preventive therapy during infancy does not adversely effect growth among HIV-exposed uninfected children: secondary analysis of data from a randomized controlled trial

Background

Isoniazid preventive therapy (IPT) decreases risk of tuberculosis (TB) disease; impact on long-term infant growth is unknown. In a recent randomized trial (RCT), we assessed IPT effects on infant growth without known TB exposure.

Methods

The infant TB Infection Prevention Study (iTIPS) trial was a non-blinded RCT among HIV-exposed uninfected (HEU) infants in Kenya. Inclusion criteria included age 6-10 weeks, birthweight ≥2.5 kg, and gestation ≥37 weeks. Infants in the IPT arm received 10 mg/kg isoniazid daily for 12 months, while the control trial received no intervention; post-trial observational follow-up continued through 24 months of age. We used intent-to-treat linear mixed-effects models to compare growth rates (weight-for-age z-score [WAZ] and height-for-age z-score [HAZ]) between trial arms.

Results

Among 298 infants, 150 were randomized to IPT, 47.6% were females, median birthweight was 3.4 kg (interquartile range [IQR] 3.0-3.7), and 98.3% were breastfed. During the 12-month intervention period and 12-month post-RCT follow-up, WAZ and HAZ declined significantly in all children, with more HAZ decline in male infants. There were no growth differences between trial arms, including in sex-stratified analyses. In longitudinal linear analysis, mean WAZ (β=0.04 [95% CI:-0.14, 0.22]), HAZ (β=0.14 [95% CI:-0.06, 0.34]), and WHZ [β=-0.07 [95% CI: -0.26, 0.11]) z-scores were similar between arms as were WAZ and HAZ growth trajectories. Infants randomized to IPT had higher monthly WHZ increase (β to 24 months 0.02 [95% CI:0.01, 0.04]) than the no-IPT arm.

Conclusion

IPT administered to HEU infants did not significantly impact growth outcomes in the first two years of life.

Timing of maternal isoniazid preventive therapy on tuberculosis infection among infants exposed to HIV in low-income and middle-income settings: a secondary analysis of the TB APPRISE trial

BACKGROUND

Infants born to women with HIV in settings with a high tuberculosis burden are at risk of tuberculosis infection and rapid progression to active disease. Maternal isoniazid preventive therapy might mitigate this risk, but optimal timing of therapy remains unclear. The TB APPRISE trial showed that initiation of isoniazid during pregnancy resulted in more frequent adverse pregnancy outcomes than when initiated postpartum. We aimed to determine the proportion of infants testing positive for tuberculosis infection born to mothers who initiated isoniazid therapy antepartum compared with postpartum using two commonly used tests, the test agreement, and predictors of test positivity.

METHODS

TB APPRISE was a randomised, double-blind, placebo-controlled, non-inferiority trial done at 13 study sites across eight countries (Botswana, Haiti, India, South Africa, Tanzania, Thailand, Uganda, and Zimbabwe). Pregnant women with HIV on antiretroviral therapy were randomly assigned to receive immediate isoniazid preventive therapy (28 weeks isoniazid [300 mg daily], then placebo until week 40 after delivery) or deferred treatment (placebo until week 12 after delivery, then isoniazid [300 mg daily] for 28 weeks). Mother-infant pairs were followed up until 48 weeks after delivery. We included all liveborn infants with a tuberculin skin test or interferon-γ release assay (IGRA) at 44 weeks. The outcomes assessed in this secondary analysis were tuberculosis test positivity by study group, test agreement, and predictors of test positivity. This study was registered with ClinicalTrials.gov, NCT01494038.

FINDINGS

Between Aug 19, 2014, and April 4, 2016, 956 mothers were randomly assigned, and 749 mother-child pairs were included in this secondary analysis. Of 749 infants, 694 (93%) received Bacille Calmette-Guérin (BCG) vaccination, 675 (90%) were born to mothers who had completed isoniazid treatment, 20 (3%) were exposed to tuberculosis, seven (1%) became HIV positive, and one (<1%) developed probable tuberculosis. 43 (6%; 95% CI 4-8]) of 732 infants had a positive IGRA test result and 55 (8%; 6-10) of 727 infants had a positive tuberculin skin test result. Test positivity did not differ by study group (p=0·88 for IGRA; p=0·44 for tuberculin skin test). Test agreement was poor (κ=0·107 [95% CI 0·002-0·212]). Infant tuberculin skin test positivity was associated with breastfeeding (adjusted odds ratio 6·63 [95% CI 1·57-27·9]), BCG vaccination (4·97 [1·50-16·43]), and maternal tuberculin skin test positivity at delivery (3·28 [1·70-6·33]); IGRA positivity was associated with female sex (2·09 [1·06-4·14]).

INTERPRETATION

Deferral of maternal isoniazid preventive therapy to early postpartum had no effect on infant tuberculosis acquisition in our trial population, regardless of the diagnostic test used; however, tuberculosis test agreement is poor during infancy.

FUNDING

US National Institutes of Health.

Cumulative Mycobacterium tuberculosis Infection Incidence (Measured Primarily by Tuberculin Skin Test) Among Infants With Human Immunodeficiency Virus Exposure: Observational Follow-up of an Isoniazid Prophylaxis Trial

Cumulative 24-month Mycobacterium tuberculosis infection incidence (measured primarily by tuberculin skin test [TST]) was high among human immunodeficiency virus exposed but uninfected infants (8.7 [95% confidence interval, 6.3-11.9] per 100 person-years). Trend for decreased TST positivity among infants at trial end (12 months postenrollment) randomized to isoniazid at 6 weeks of age was not sustained through observational follow-up to 24 months of age.

CLINICAL TRIALS REGISTRATION

NCT02613169.

A CD4+ TNF+ monofunctional memory T-cell response to BCG vaccination is associated with Mycobacterium tuberculosis infection in infants exposed to HIV

BACKGROUND

The immunologic correlates of risk of Mycobacterium tuberculosis (Mtb) infection after BCG vaccination are unknown. The mechanism by which BCG influences the tuberculin skin test (TST) remains poorly understood. We evaluated CD4+ T-cell responses in infants exposed to HIV and uninfected (HEU) who received BCG at birth and examined their role in susceptibility to Mtb infection and influence on TST induration.

METHODS

HEU infants were enrolled in a randomised clinical trial of isoniazid (INH) to prevent Mtb infection in Kenya. We measured mycobacterial antigen-specific Th1 and Th17 cytokine responses at 6-10 weeks of age prior to INH randomisation and compared responses between Mtb infected and uninfected infants. Outcomes at 14 months of age included TST, QuantiFERON-Plus (QFT-Plus), and ESAT-6/CFP-10-specific non-IFN-γ cytokines measured in QFT-Plus supernatants.

FINDINGS

A monofunctional mycobacterial antigen-specific TNF+ CD4+ effector memory (CCR7-CD45RA-) T-cell response at 6-10 weeks of age was associated with Mtb infection at 14 months of age as measured by ESAT-6/CFP-10-specific IFN-γ and non-IFN-γ responses (Odds Ratio 2.26; Confidence Interval 1.27-4.15; P = 0.006). Mycobacterial antigen-specific polyfunctional effector memory Th1 responses at 6-10 weeks positively correlated with TST induration in infants without evidence of Mtb infection at 14 months, an association which was diminished by INH therapy.

INTERPRETATION

Induction of monofunctional TNF+ CD4+ effector memory T-cell responses may be detrimental in TB vaccine development. This study also provides mechanistic insight into the association of BCG-induced immune responses with TST induration and further evidence that TST-based diagnoses of Mtb infection in infants are imprecise.

FUNDING

Thrasher Research Fund.

Interferon Gamma Release Assay and Tuberculin Skin Test Performance in Pregnant Women Living With and Without HIV

BACKGROUND

HIV and pregnancy may affect latent TB infection (LTBI) diagnostics. Tuberculin skin test (TST) and newer generation QuantiFERON-TB Gold Plus (QFT-Plus) evaluations in pregnant women living with HIV (WLHIV) and without HIV are lacking.

METHODS

In this cross-sectional study, pregnant women underwent TST and QFT-Plus testing during antenatal care in Kenya. We estimated LTBI prevalence and TST and QFT-Plus performances. Diagnostic agreement was assessed with kappa statistic, participant characteristics associated with LTBI and HIV were assessed with generalized linear models, and QFT-Plus quantitative responses were assessed with Mann-Whitney U test.

RESULTS

We enrolled 400 pregnant women (200 WLHIV/200 HIV-negative women) at median 28 weeks gestation (interquartile range 24-30). Among WLHIV (all on antiretroviral therapy), the median CD4 count was 464 cells/mm3 (interquartile range 325-654); 62.5% (125) had received isoniazid preventive therapy. LTBI prevalence was 35.8% and similar among WLHIV and HIV-negative women. QFT-Plus testing identified 3-fold more women with LTBI when compared with TST (32% vs. 12%, P < 0.0001). QFT-Plus positivity prevalence was similar regardless of HIV status, although TB-specific antigen responses were lower in WLHIV than in HIV-negative women with LTBI (median QFT-TB1 1.05 vs. 2.65 IU/mL, P = 0.035; QFT-TB2 1.26 vs. 2.56 IU/mL, P = 0.027). TST positivity was more frequent among WLHIV than among HIV-negative women (18.5% vs 4.6%; P < 0.0001).

CONCLUSIONS

QFT-Plus assay had higher diagnostic yield than TST for LTBI in WLHIV and HIV-negative women despite lower TB-specific antigen responses in WLHIV. Higher TST positivity was observed in WLHIV. LTBI diagnostic performance in the context of pregnancy and HIV has implications for clinical use and prevention studies, which rely on these diagnostics for TB infection entry criteria or outcomes.

Urine Biomarker Assessment of Infant Adherence to Isoniazid Prophylaxis

We assessed adherence in an infant tuberculosis prevention trial in Kenya with a urine isoniazid metabolite-detecting dipstick. Ninety-seven infants had 155 assays performed; 77 (49.7%) were found to be positive despite caregiver-reported adherence. Positive assays were associated with maternal secondary education, HIV suppression and no reported missed doses in past 3 days, suggesting caregiver education and self-medication use influenced infant adherence.