Incidence and risk factors of loss to follow-up among HIV-infected children in an antiretroviral treatment program.

INTRODUCTION: The success of antiretroviral treatment (ART) programs can be compromised by high rates of patient loss to follow-up (LTFU). We assessed the incidence and risk factors of LTFU in a large cohort of HIV-infected children receiving ART in Thailand. METHODS: All children participating in a multicenter cohort (NCT00433030) between 1999 and 2014 were included. The date of LTFU was 9 months after the last contact date. ART interruption was defined as ART discontinuation for more than 7 days followed by resumption of treatment. Baseline and time-dependent risk factors associated with LTFU were identified using Fine and Gray competing risk regression models with death or referral to another hospital as competing events. RESULTS: Of 873 children who were followed during a median of 8.6 years (interquartile range 4.5-10.6), 196 were LTFU, 73 died, and 195 referred. The cumulative incidence of LTFU was 2.9% at 1 year, 7.3% at 5 years and 22.2% at 10 years. Children aged 13 years and more had a 3-fold higher risk (95% confidence interval 2.06-4.78) of LTFU than those younger. Children who had interrupted ART within the previous year had a 2.5-fold higher risk (1.12-5.91) than those who had not. The risk of LTFU was lower in children stunted (height-for-age Z-scores <-2 SD) (0.42-0.96) or underweight (weight-for-age Z-scores <-2 SD) (0.24-0.97). CONCLUSION: Adolescence, ART interruption and absence of growth deficit were associated with LTFU. These may be warnings that should draw clinicians' attention and possibly trigger specific interventions. Children with no significant growth retardation may also be at risk of LTFU.

Role of efavirenz plasma concentrations on long-term HIV suppression and immune restoration in HIV-infected children.

BACKGROUND: To access the long term relationship between efavirenz plasma concentrations and evolution of HIV RNA loads and CD4 cell counts in children. METHODS: Retrospective analysis of data from HIV-infected children on first line efavirenz-containing regimen. A population pharmacokinetic-pharmacodynamic (PK-PD) model was developed to describe the evolution of HIV RNA load and CD4 cell count (efficacy outcomes) in relation to efavirenz plasma concentration. Individual CYP2B6 516 G>T genotype data were not available for this analysis. A score (ISEFV) quantifying the effect of efavirenz concentrations on the long-term HIV replication was calculated from efavirenz concentrations and PD parameters and, a value of ISEFV below which HIV replication is likely not suppressed was determined. Cox proportional hazards regression models were used to assess the association of the risk of viral replication with ISEFV, and with efavirenz mid-dose concentration(C12). RESULTS: At treatment initiation, median (interquartile range, IQR) age was 8 years (5 to 10), body weight 17 kg (14 to 23), HIV RNA load 5.1 log10 copies/mL (4.6 to 5.4), and CD4 cell count 71 cells/mm3. A model of PK-PD viral dynamics assuming that efavirenz decreases the rate of infected host cells adequately described the relationship of interest. After adjusting for age, baseline HIV RNA load and CD4 cell counts an ISEFV <85% was significantly associated with a higher risk of viral replication (p-value <0.001) while no significant association was observed with C12 <1.0 mg/L. CONCLUSION: The ISEFV score was a good predictor of viral replication in children on efavirenz-based treatment.

Maternal and Infant Bone Mineral Density 1 Year After Delivery in a Randomized, Controlled Trial of Maternal Tenofovir Disoproxil Fumarate to Prevent Mother-to-child Transmission of Hepatitis B Virus.

In a randomized, double-blind, placebo-controlled trial of tenofovir disoproxil fumarate (TDF) use from 28 weeks gestational age to 2 months postpartum to prevent mother-to-child transmission of hepatitis B virus, there was no significant effect of maternal TDF use on maternal or infant bone mineral density 1 year after delivery/birth. Clinical Trials Registration. NCT01745822.

Assessment of Nevirapine Prophylactic and Therapeutic Dosing Regimens for Neonates.

BACKGROUND: Nevirapine (NVP) is a key component of antiretroviral prophylaxis and treatment for neonates. We evaluated current World Health Organization (WHO) weight-band NVP prophylactic dosing recommendations and investigated optimal therapeutic NVP dosing for neonates. METHODS: The PHPT-5 study in Thailand assessed the efficacy of "Perinatal Antiretroviral Intensification" to prevent mother-to-child transmission of HIV in women with <8 weeks of antiretroviral treatment before delivery (NCT01511237). Infants received a 2-week course of zidovudine/lamivudine/NVP (NVP syrup/once daily: 2 mg/kg for 7 days; then 4 mg/kg for 7 days). Infant samples were assessed during the first 2 weeks of life. NVP population pharmacokinetics (PK) parameters were estimated using nonlinear mixed-effects models. Simulations were performed to estimate the probability of achieving target NVP trough concentrations for prophylaxis (>0.10 mg/L) and for therapeutic efficacy (>3.0 mg/L) using different infant dosing strategies. RESULTS: Sixty infants (55% male) were included. At birth, median (range) weight was 2.9 (2.3-3.6) kg. NVP concentrations were best described by a 1-compartment PK model. Infant weight and postnatal age influenced NVP PK parameters. Based on simulations for a 3-kg infant, ≥92% would have an NVP trough >0.1 mg/L after 48 hours through 2 weeks using the PHPT-5 and WHO-dosing regimens. For NVP-based therapy, a 6-mg/kg twice daily dose produced a trough >3.0 mg/L in 87% of infants at 48 hours and 80% at 2 weeks. CONCLUSION: WHO weight-band prophylactic guidelines achieved target concentrations. Starting NVP 6 mg/kg twice daily from birth is expected to achieve therapeutic concentrations during the first 2 weeks of life.

Incidence of Tuberculosis and Associated Mortality in a Cohort of Human Immunodeficiency Virus-Infected Children Initiating Antiretroviral Therapy.

BACKGROUND.: We assessed the incidence of tuberculosis, risk factors for tuberculosis, and the contribution of tuberculosis on mortality in a large cohort of human immunodeficiency virus (HIV)-infected children <15 years of age initiating first-line antiretroviral therapy (ART) between 1999 and 2012 in Thailand, one of the 22 high tuberculosis burden countries. METHODS.: A physician reviewed and classified tuberculosis cases. Incidence was the number of children with incident tuberculosis, defined as a first or recurrent tuberculosis diagnosis >30 days after ART initiation, divided by the total person-years of follow-up (PYFU). Risk factors for incident tuberculosis were identified using Fine and Gray's competing risks models, with death from other causes treated as a competing event, and risk factors for death were identified using Cox models. RESULTS.: At ART initiation, 670 children (55% female) had a median age of 6.4 years (interquartile range, 2.0-9.6), body mass index-for-age z-score -0.8 (-1.9 to 0.0), HIV ribonucleic acid viral load 5.1 log10 copies/mL (4.6-5.6), and CD4 9% (3-17). Median duration of follow-up was 7.7 years. Tuberculosis incidence was 7 per 1000 PYFU (95% confidence interval [CI], 5-11) and decreased with ART duration. Lower age-adjusted hemoglobin, hematocrit, and CD4 at ART initiation were associated with a higher risk of incident tuberculosis. Of the 30 incident tuberculosis cases, 9 died. Diagnosis of incident tuberculosis was associated with mortality (unadjusted hazard ratio = 10.2, 95% CI = 4.8-21.5, P < .001 and adjusted hazard ratio = 5.4, 95% CI = 2.5-11.7, P < .001). CONCLUSIONS.: Incident tuberculosis was strongly associated with mortality. CD4 counts or hemoglobin or hematocrit levels may prompt clinicians to consider a possible tuberculosis infection.

Contribution of different antiretroviral regimens containing zidovudine, lamivudine and ritonavir-boosted lopinavir on HIV viral load reduction during pregnancy.

BACKGROUND: Antiretroviral (ARV) regimens used for the prevention of mother-to-child transmission of HIV have evolved over time. We evaluated the contribution of different ARV regimens on the reduction of the plasma HIV RNA viral load (VL) during pregnancy. METHODS: A total of 1,833 VL measurements from ARV-naive pregnant women participating in perinatal prevention trials in Thailand were included. Women received either zidovudine (ZDV) monotherapy, ZDV plus lopinavir/ritonavir (LPV/r), or ZDV plus lamivudine (3TC) plus LPV/r. VL time-course during pregnancy was described as a function of pretreatment VL and treatment duration using an Emax non-linear mixed-effect model. VL reduction and median time to achieve a VL<50 copies/ml were estimated for each regimen. RESULTS: Among 745 women, 279 (37%), 145 (20%) and 321 (43%) received ZDV monotherapy, ZDV+LPV/r and ZDV+3TC+LPV/r, respectively. The predicted VL reduction from baseline to delivery after a median of 10 weeks of treatment were 0.5, 2.7 and 2.9 log10 copies/ml with ZDV monotherapy, ZDV+LPV/r and ZDV+3TC+LPV/r, respectively. At delivery, 1%, 57% and 63% of women receiving ZDV monotherapy, ZDV+LPV/r or ZDV+3TC+LPV/r had a VL<50 copies/ml. The addition of 3TC to ZDV+LPV/r reduced the time to achieve a VL<50 copies/ml and the higher the pretreatment VL, the larger the effect 3TC had on reducing the time to VL<50 copies/ml. CONCLUSIONS: The addition of 3TC to ZDV+LPV/r was associated with a slight further VL reduction but the time to reach a VL<50 copies/ml was shorter. This beneficial effect of 3TC is crucial for prevention of mother-to-child transmission in women who receive ARVs late and with high pretreatment VL.