Addy Kekitiinwa

Differences in factors associated with initial growth CD4 and viral load responses to ART in HIV-infected children in Kampala Uganda and the United Kingdom/Ireland.

Background:Few studies have directly compared response to antiretroviral therapy (ART) between children living in well-resourced and resource-limited settings. In resource-limited settings non-HIV contributors could reduce the beneficial effects of ART. We compare predictors of short-term immunological, virological, and growth response to ART in HIV-infected children in the United Kingdom/Ireland and Kampala. Methods:We analyzed prospective cohort data from 54 UK/Irish hospitals (the Collaborative HIV Paediatric Study) and Mulago Hospital, Kampala, Uganda. Six- and 12-month responses are described among children initiating combination ART (≥3 drugs, ≥2 classes). Six months post-ART, predictors of viral load (VL) suppression <400 copies/mL, CD4% increases >10%, and height- and weight-for-age z-score increases ≥+0.5 were investigated using logistic regression. Results:In all, 582 UK/Irish children (76% black African) were younger than 876 Kampala children at ART initiation (median 5.0 vs 7.6 years), with higher CD4% (14%, 8%), lower VL (172,491 and 346,809 copies/mL), and less stunting (−0.8, −2.8) and wasting (−0.6, −2.8). Post-ART, median 12-month changes in the United Kingdom/Ireland and Kampala in CD4% (+12%, +13%) and weight (+0.4, +0.5) were similar, but growth was less in Kampala (+0.20, +0.06, P < 0.001). Younger children in both cohorts had better immunological, weight, and growth responses (all P < 0.001). However, lower pre-ART CD4% predicted better immunological response in the United Kingdom/Ireland but poorer response in Kampala (heterogeneity P = 0.004). Although 70% children in both cohorts had suppressed <400 copies/mL at 6 months, adolescents starting ART in the United Kingdom/Ireland had somewhat poorer VL responses than those in Kampala (P = 0.15). Conclusions:Overall immunological and virologic ART responses were similar in children in both cohorts. Poorer CD4 recovery in more immunosuppressed Kampala children and blunted growth responses likely reflect higher background malnutrition and infection rates in Uganda, suggesting the need for earlier HIV diagnosis, nutritional support, cotrimoxazole prophylaxis, and ART.

Extensive Polymorphism in Cryptosporidium parvum Identified by Multilocus Microsatellite Analysis

ABSTRACT Restriction fragment length polymorphism and DNA sequence analysis discern two main types of Cryptosporidium parvum. We present a survey of length polymorphism at several microsatellite loci for type 1 and type 2 isolates. A total of 14 microsatellite loci were identified from C. parvum DNA sequences deposited in public databases. All repeats were mono-, di-, and trinucleotide repeats of A, AT, and AAT, reflecting the high AT content of the C. parvum genome. Several of these loci showed significant length polymorphism, with as many as seven alleles identified for a single locus. Differences between alleles ranged from 1 to 27 bp. Karyotype analysis using probes flanking three microsatellites localized each marker to an individual chromosomal band, suggesting that these markers are single copy. In a sample of 19 isolates for which at least three microsatellites were typed, a majority of isolates displayed a unique multilocus fingerprint. Microsatellite analysis of isolates passaged between different host species identified genotypic changes consistent with changes in parasite populations.

Mortality in the Year Following Antiretroviral Therapy Initiation in HIV-Infected Adults and Children in Uganda and Zimbabwe

In low-income countries, children ≥4 years and adults with low CD4 count have equally high mortality risk in the 3 months after initiation of antiretroviral therapy, similar to that of untreated individuals. Bacterial infections play a major role; targeted interventions could have important benefits.

Tuberculosis in human immunodeficiency virus infected Ugandan children starting on antiretroviral therapy

OBJECTIVE To identify the incidence of tuberculosis (TB) in human immunodeficiency virus (HIV) infected children in a resource-limited setting before and after initiation of antiretroviral therapy (ART), and to assess the impact of TB screening by tuberculin skin testing and clinical history. METHODS A retrospective cohort study of 1806 HIV-infected children and adolescents (age <18 years) initiating ART from 2003 to 1 July 2006 in Kampala, Uganda. A TB screening program was instituted clinic-wide in January 2006. RESULTS Of 311 (17.2%) HIV-infected children, 171 had been diagnosed with TB before and 140 after ART initiation. During the first 100 days of ART, risk of a new TB diagnosis was 2.7-fold higher compared to the pre-ART period (RR 2.7, 95%CI 2.1-3.5, P < 0.001). After 100 days of ART, the TB incidence rate decreased to below pre-ART levels (RR 0.41, 95%CI 0.30-0.54, P = 0.002). After TB screening was instituted in 2006, the proportion of new TB cases diagnosed after starting ART decreased by 70% (95%CI 51-82, P < 0.001), abating the early excess risk. CONCLUSIONS TB is common among African children and adolescents initiating ART in sub-Saharan Africa. More aggressive screening for active TB before starting ART can diminish the rate of TB during immune reconstitution. Future studies are needed to determine optimal screening practices for HIV-infected children.

Plasma Efavirenz Exposure, Sex, and Age Predict Virological Response in HIV-Infected African Children

Background:Owing to insufficient evidence in children, target plasma concentrations of efavirenz are based on studies in adults. Our analysis aimed to evaluate the pediatric therapeutic thresholds and characterize the determinants of virological suppression in African children. Methods:We analyzed data from 128 African children (aged 1.7–13.5 years) treated with efavirenz, lamivudine, and one among abacavir, stavudine, or zidovudine, and followed up to 36 months. Individual pharmacokinetic (PK) measures [plasma concentration 12 hours after dose (C12h), plasma concentration 24 hours after dose (C24h), and area under the curve (AUC0-24)] were estimated using population PK modeling. Cox multiple failure regression and multivariable fractional polynomials were used to investigate the risks of unsuppressed viral load associated with efavirenz exposure and other factors among 106 initially treatment-naive children, and likelihood profiling was used to identify the most predictive PK thresholds. Results:The risk of viral load >100 copies per milliliter decreased by 42% for every 2-fold increase in efavirenz mid-dose concentration [95% confidence interval (CI): 23% to 57%; P < 0.001]. The most predictive PK thresholds for increased risk of unsuppressed viral load were C12h 1.12 mg/L [hazard ratio (HR): 6.14; 95% CI: 2.64 to 14.27], C24h 0.65 mg/L (HR: 6.57; 95% CI: 2.86 to 15.10), and AUC0-24 28 mg·h/L (HR: 5.77; 95% CI: 2.28 to 14.58). Children older than 8 years had a more than 10-fold increased risk of virological nonsuppression (P = 0.005); among children younger than 8 years, boys had a 5.31 times higher risk than girls (P = 0.007). Central nervous system adverse events were infrequently reported. Conclusions:Our analysis suggests that the minimum target C24h and AUC0-24 could be lowered in children. Our findings should be confirmed in a prospective pediatric trial.

The impact of genetic polymorphisms on the pharmacokinetics of efavirenz in African children.

Aims Using a model‐based approach, the efavirenz steady‐state pharmacokinetics in African children is characterized, quantifying demographic and genotypic effects on the drugs disposition. Simulations are also conducted allowing prediction of optimized doses of efavirenz in this population. Methods We modelled the steady‐state population pharmacokinetics of efavirenz in Ugandan and Zambian children using nonlinear mixed‐effects modelling. Individual mid‐dose efavirenz concentrations were derived and simulations explored genotype‐based dose optimization strategies. Results A two‐compartment model with absorption through transit compartments well described 2086 concentration‐time points in 169 children. The combined effect of single nucleotide polymorphisms (SNPs) 516G>T and 983T>C explained 44.5% and 14.7% of the variability in efavirenz clearance and bioavailability, respectively. The detected frequencies of composite CYP2B6 genotype were 0.33 for 516GG|983TT, 0.35 for 516GT|983TT, 0.06 for 516GG|983TC, 0.18 for 516TT|983TT, 0.07 516GT|983TC and 0.01 for 516GG|983CC. The corresponding estimated clearance rates were 6.94, 4.90, 3.93, 1.92, 1.36, and 0.74 l h−1 for a 15.4 kg child and median (95% CI) observed mid‐dose concentrations 1.55 (0.51–2.94), 2.20 (0.97–4.40), 2.03 (1.19–4.53), 7.55 (2.40–14.74), 7.79 (3.66–24.59) and 18.22 (11.84–22.76) mg l−1, respectively. Simulations showed that wild‐type individuals had exposures at the bottom of therapeutic range, while slower metabolizers were overexposed. Conclusions Dosage guidelines for African children should take into consideration the combined effect of SNPs CYP2B6 516G>T and 983T>C.

Effect of diurnal variation, CYP2B6 genotype and age on the pharmacokinetics of nevirapine in African children

Objectives To characterize the effects of CYP2B6 polymorphisms, diurnal variation and demographic factors on nevirapine pharmacokinetics in African children. Methods Non-linear mixed-effects modelling conducted in NONMEM 7.3 described nevirapine plasma concentration–time data from 414 children aged 0.3–15 years. Results Nevirapine pharmacokinetics was best described using a one-compartment disposition model with elimination through a well-stirred liver model accounting for a first-pass effect and transit-compartment absorption. Intrinsic clearance was affected by diurnal variation (characterized using a cosine function with peak amplitude 29% at 12 noon) and CYP2B6 metabolizer status [extensive metabolizer (EM) 516GG|983TT, reference; intermediate metabolizer (IM) 516GT|983TT or 516GG|983TC, 17% lower; slow metabolizer (SM) 516TT|983TT or 516GT|983TC, 50% lower; ultra-slow metabolizer (USM) 516GG|983CC, 68% lower]. Age was found to affect pre-hepatic bioavailability: 31.7% lower at birth and increasing exponentially. Median (90% CI) evening Cmin values in the different metabolizer groups were 5.01 (3.01–7.47), 6.55 (3.65–13.32), 11.59 (5.44–22.71) and 12.32 (12.32–27.25) mg/L, respectively. Evening Cmin values were <3 mg/L in 43% of EM weighing <6 kg and 26% of IM weighing <6 kg, while 73% of SM and 88% of USM in all weight-bands had evening Cmin values >8 mg/L. Cmin was not markedly affected by administration time, but was altered by unequal splitting of the daily dose. Conclusions Diurnal variation does not greatly affect nevirapine exposure. However, when daily doses cannot be split equally, the larger dose should be given in the morning. To achieve homogeneous exposures, nevirapine doses for SM and USM should be reduced by 50%, and children weighing <6 kg with EM or IM metabolizer status should receive the same dose as children weighing 6–10 kg.

Determinants of virological outcome and adverse events in African children treated with paediatric nevirapine fixed-dose-combination tablets

Background: Nevirapine is the only nonnucleoside reverse transcriptase inhibitor currently available as a paediatric fixed-dose-combination tablet and is widely used in African children. Nonetheless, the number of investigations into pharmacokinetic determinants of virological suppression in African children is limited, and the predictive power of the current therapeutic range was never evaluated in this population, thereby limiting treatment optimization. Methods: We analysed data from 322 African children (aged 0.3–13 years) treated with nevirapine, lamivudine, and either abacavir, stavudine, or zidovudine, and followed up to 144 weeks. Nevirapine trough concentration (Cmin) and other factors were tested for associations with viral load more than 100 copies/ml and transaminase increases more than grade 1 using proportional hazard and logistic models in 219 initially antiretroviral treatment (ART)-naive children. Results: Pre-ART viral load, adherence, and nevirapine Cmin were associated with viral load nonsuppression [hazard ratio = 2.08 (95% confidence interval (CI): 1.50–2.90, P < 0.001) for 10-fold higher pre-ART viral load, hazard ratio = 0.78 (95% CI: 0.68–0.90, P < 0.001) for 10% improvement in adherence, and hazard ratio = 0.94 (95% CI: 0.90–0.99, P = 0.014) for a 1 mg/l increase in nevirapine Cmin]. There were additional effects of pre-ART CD4+ cell percentage and clinical site. The risk of virological nonsuppression decreased with increasing nevirapine Cmin, and there was no clear Cmin threshold predictive of virological nonsuppression. Transient transaminase elevations more than grade 1 were associated with high Cmin (>12.4 mg/l), hazard ratio = 5.18 (95% CI 1.95–13.80, P < 0.001). Conclusion: Treatment initiation at lower pre-ART viral load and higher pre-ART CD4+ cell percentage, increased adherence, and maintaining average Cmin higher than current target could improve virological suppression of African children treated with nevirapine without increasing toxicity.

Decentralisation of child tuberculosis services increases case finding and uptake of preventive therapy in Uganda

BACKGROUND A lack of capacity to diagnose tuberculosis (TB) in children at peripheral health facilities and limited contact screening and management contribute to low case finding in TB-endemic settings. OBJECTIVE To evaluate the implementation of a pilot project that strengthened diagnosis, treatment and prevention of child TB at peripheral health facilities in Uganda. METHODS In June 2015, health care workers at peripheral health facilities were trained to diagnose and treat child TB. Community health care workers were trained to screen household TB contacts. Before-and-after analysis as well as comparisons with non-intervention districts were used to evaluate impact on caseload and treatment outcomes. RESULTS By December 2016, the average number of children (age < 15 years) diagnosed with TB increased from 45 to 108 per quarter. The proportion of child TB among all TB cases increased from 8.8% to 15%, and the proportion completing treatment increased from 65% to 82%. Of 2270 child TB contacts screened, 55 (2.4%) were diagnosed with TB. Of 910 eligible child contacts, 670 (74%) started preventive therapy, 569 (85%) of whom completed therapy. CONCLUSION The strengthening of child TB services at peripheral health facilities in Uganda was associated with increased case finding, improved treatment outcomes and the successful implementation of contact screening and management.