Steve Innes

White matter signal abnormalities in children with suspected HIV-related neurologic disease on early combination antiretroviral therapy.

Background: The natural history and manifestation of HIV-related neurologic disease have been ameliorated by combination antiretroviral therapy (ART). We describe the characteristics of white matter signal abnormalities (WMSA) on magnetic resonance imaging in children with HIV-related neurologic disease. Methods: We reviewed magnetic resonance imaging scans of children with suspected HIV-related neurologic disease despite early ART and correlated with clinical, neurodevelopmental data, virologic markers and time on ART. These children were also on the Children with HIV Early Antiretroviral (CHER) trial. Results: Magnetic resonance imaging scans were performed at a mean age 31.9 months (range 8–54) on 44 children: 10 on deferred and 34 on early treatment arms, commencing ART at mean age of 18.5 and 8 weeks, respectively. Multiple high signal intensity lesions on T2/fluid attenuated inversion recovery were documented in 22 patients (50%), predominantly in frontal (91%) and parietal (82%) white matter. No differences in neurodevelopmental scores comparing children with and without WMSA were found. Neither lesion load nor distribution showed significant correlation with neurodevelopmental scores or neurologic examination. Normal head growth was more common in the WMSA group (P = 0.01). There was a trend for association of WMSA and longer time on ART (P = 0.13) and nadir CD4% (P = 0.08). Conclusions: Half of children referred with HIV-related brain disease had WMSA on T2/fluid attenuated inversion recovery. Our findings of the association with normal head growth and duration of ART require further study. We suspect that WMSA can occur early and that initiating ART by 8 weeks of life may be too late to prevent HIV from entering the central nervous system.

High prevalence of lipoatrophy in pre-pubertal South African children on antiretroviral therapy: a cross-sectional study

BackgroundDespite changes in WHO guidelines, stavudine is still used extensively for treatment of pediatric HIV in the developing world. Lipoatrophy in sub-Saharan African children can be stigmatizing and have far-reaching consequences. The severity and extent of lipoatrophy in pre-pubertal children living in sub-Saharan Africa is unknown.MethodsIn this cross-sectional study, children who were 3-12 years old, on antiretroviral therapy and pre-pubertal were recruited from a Family HIV Clinic in South Africa. Lipoatrophy was identified and graded by consensus between two HIV pediatricians using a standardized grading scale. A professional dietician performed formal dietary assessment and anthropometric measurements of trunk and limb fat. Previous antiretroviral exposures were recorded. In a Dual-Energy X-ray Absorbtiometry (DXA) substudy body composition was determined in 42 participants.ResultsAmong 100 recruits, the prevalence of visually obvious lipoatrophy was 36% (95% CI: 27%–45%). Anthropometry and DXA measurements corroborated the clinical diagnosis of lipoatrophy: Both confirmed significant, substantial extremity fat loss in children with visually obvious lipoatrophy, when adjusted for age and sex. Adjusted odds ratio for developing lipoatrophy was 1.9 (95% CI: 1.3 - 2.9) for each additional year of accumulated exposure to standard dose stavudine. Cumulative time on standard dose stavudine was significantly associated with reductions in biceps and triceps skin-fold thickness (p=0.008).ConclusionsThe prevalence of visually obvious lipoatrophy in pre-pubertal South African children on antiretroviral therapy is high. The amount of stavudine that children are exposed to needs review. Resources are needed to enable low-and-middle-income countries to provide suitable pediatric-formulated alternatives to stavudine-based pediatric regimens. The standard stavudine dose for children may need to be reduced. Diagnosis of lipoatrophy at an early stage is important to allow timeous antiretroviral switching to arrest progression and avoid stigmatization. Diagnosis using visual grading requires training and experience, and DXA and comprehensive anthropometry are not commonly available. A simple objective screening tool is needed to identify early lipoatrophy in resource-limited settings where specialized skills and equipment are not available.

Effect of reducing the paediatric stavudine dose by half: A physiologically-based pharmacokinetic model

Owing to significant dose-related toxicity, the adult stavudine dose was reduced in 2007. The paediatric dose, however, has not been reduced. Although the intended paediatric dose is 1 mg/kg twice daily (b.i.d.), the current weight-band dosing approach results in a mean actual dose of 1.23±0.47 mg/kg. Both efficacy and mitochondrial toxicity depend on the concentration of the intracellular metabolite stavudine triphosphate (d4T-TP). We simulated the effect of reducing the paediatric dose to 0.5 mg/kg. A physiologically-based pharmacokinetic model consisting of 13 tissue compartments plus a full ADAM model was used to describe the elimination of stavudine. The volume of distribution at steady-state and apparent oral clearance were simulated and the resulting AUC profile was compared with literature data in adult and paediatric populations. A biochemical reaction model was utilised to simulate intracellular d4T-TP levels for both the standard and proposed reduced paediatric doses. Simulated and observed exposure after oral dosing showed adequate agreement. Mean steady-state d4T-TP for 1.23 mg/kg b.i.d. was 27.9 (90% CI 27.0-28.9) fmol/10(6) cells, 25% higher than that achieved by the 40 mg adult dose. The 0.5 mg/kg dose resulted in d4T-TP of 13.2 (12.7-13.7) fmol/10(6) cells, slightly higher than the adult dose of 20 mg b.i.d. [11.5 (11.2-11.9) fmol/10(6) cells], which has excellent antiviral efficacy and substantially less toxicity. Current paediatric dosing may result in even higher d4T-TP than the original 40 mg adult dose. Halving the paediatric dose would significantly reduce the risk of mitochondrial toxicity without compromising antiviral efficacy.

High Prevalence of Dyslipidemia and Insulin Resistance in HIV-infected Prepubertal African Children on Antiretroviral Therapy.

Background: Data describing the true extent of antiretroviral therapy (ART)–induced dyslipidemia and insulin resistance in perinatally infected children on ART in Africa are sparse. Methods: Fasting total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, insulin and glucose were performed on the first 100 of 190 pediatric ART clinic attendees. Diet assessment was performed by a trained dietician. Lipoatrophy was formally graded by consensus between 2 expert HIV pediatricians. Durations of previous ART exposures, clinical stage, pre-ART viral load, nadir and current CD4 were recorded. Dual-energy X-ray absorptiometry was performed on a subset of 42 patients selected semi-randomly. Results: Prevalences of insulin resistance, abnormal total cholesterol, LDL, HDL and triglyceride were 10%, 13%, 12%, 13% and 9%, respectively. Overall, 40% had at least 1 lipid abnormality or insulin resistance. Adjusted mean LDL cholesterol increased by 0.24 mmol/L for each additional year of cumulative lopinavir/r exposure (P = 0.03) after correcting for age, gender, body mass index, previous stavudine exposure, age at ART initiation, dietary fat and refined carbohydrate, whereas adjusted mean LDL cholesterol was 0.9 mmol/L higher in children exposed to efavirenz within the previous 6 months (P = 0.02). Adjusting for age, gender and ethnicity, dual-energy X-ray absorptiometry revealed that greater trunk fat and lower peripheral subcutaneous fat were associated with elevated triglycerides but not with total cholesterol, LDL, HDL or homeostatic model assessment. Similarly, the presence of visually obvious lipoatrophy was associated with elevated triglycerides but not with total cholesterol, LDL, HDL, homeostatic model assessment or lactate. Conclusions: Prevalences of insulin resistance and dyslipidemia were high. Cumulative lopinavir is an independent risk factor for dyslipidemia, with efavirenz exposure having only transitory effect.

Estimation of Intracellular Concentration of Stavudine Triphosphate in HIV-Infected Children Given a Reduced Dose of 0.5 Milligrams per Kilogram Twice Daily

ABSTRACT The antiviral efficacy of stavudine depends on the trough concentration of its intracellular metabolite, stavudine-triphosphate (d4T-TP), while the degree of stavudines mitochondrial toxicity depends on its peak concentration. Rates of mitochondrial toxicity are high when stavudine is used at the current standard pediatric dose (1 mg/kg twice daily [BID]). Evidence from adult work suggests that half of the original standard adult dose (i.e., 20 mg BID) may be equally effective, with markedly less mitochondrial toxicity. We present a population pharmacokinetic model to predict intracellular d4T-TP concentrations in pediatric HIV-infected patients administered a dose of 0.5 mg/kg BID. Our model predicted that the reduced pediatric dose would result in a trough intracellular d4T-TP concentration above that of the reduced 20-mg adult dose and a peak concentration below that of the 20-mg adult dose. The simulated pediatric intracellular d4T-TP at 0.5 mg/kg BID resulted in median peak and trough values of approximately 23.9 fmol/106 cells (95% prediction interval [PI], 14.2 to 41 fmol/106 cells) and 14.8 fmol/106 cells (95% PI, 7.2 to 31 fmol/106 cells), respectively. The peak and trough concentrations resulting from a 20-mg BID adult dose were 28.4 fmol/106 cells (95% PI, 17.3 to 45.5 fmol/106 cells) and 13 fmol/106 cells (95% PI, 6.8 to 28.6 fmol/106 cells), respectively. Halving the current standard pediatric dose should therefore not compromise antiviral efficacy, while markedly reducing mitochondrial toxicity.

Biceps skin-fold thickness may detect and predict early lipoatrophy in HIV-infected children

Background: The prevalence of potentially stigmatizing lipoatrophy in children receiving antiretroviral therapy in Southern Africa is high, affecting around a third of children. Early diagnosis of lipoatrophy is essential for effective intervention to arrest progression. Methods: Prepubertal children receiving antiretroviral therapy were recruited from a hospital-based family HIV clinic in Cape Town and followed up prospectively. Lipoatrophy was identified and graded by consensus between 2 HIV pediatricians. A dietician performed anthropometric measurements of trunk and limb fat. Anthropometric measurements in children with and without lipoatrophy were compared using multivariable linear regression adjusting for age and gender. The most discerning anthropometric indicators of lipoatrophy underwent receiver operating characteristic curve analysis. The precision of anthropometric measurements performed by an inexperienced healthcare worker was compared with that of a research dietician. Results: Of 100 recruits, 36 had lipoatrophy at baseline and a further 9 developed lipoatrophy by 15-month follow-up. Annual incidence of lipoatrophy was 12% (confidence interval [CI]: 5–20%) per person-year of follow-up. A biceps skin-fold thickness <5 mm at baseline had a sensitivity of 89% (CI: 67–100%) and a specificity of 60% (CI: 46–75%) for predicting development of lipoatrophy by 15-month follow-up. Negative and positive predictive values were 97% (CI: 91–100%) and 32% (CI: 14–50%). Conclusion: Biceps skin-fold thickness <5 mm in prepubertal children exposed to thymidine analogue-based antiretroviral therapy may be a useful screening tool to identify children who are likely to develop lipoatrophy. The variation in precision of measurements performed by an inexperienced healthcare worker only marginally impacted performance.

Lipoatrophy/lipohypertrophy outcomes after antiretroviral therapy switch in children in the UK/Ireland

Background Following widespread use of stavudine, a thymidine analogue, in antiretroviral therapy (ART) over the past three decades, up to a third of children developed lipoatrophy (LA) and/or lipohypertrophy (LH). Following phasing-out of stavudine, incidence of newly-diagnosed LA and LH declined dramatically. However, the natural history of existing cases should be explored, particularly with prolonged protease inhibitor exposure. Methods The Collaborative HIV Paediatric Study (CHIPS) is a multicentre cohort study of most HIV-infected children in the United Kingdom and Ireland. Those on ART with a LA/LH assessment recorded in 2003–2011 were included. Assessments were completed annually by consultant physicians. Using the 0–3 grading system, LA or LH was defined as grade 2 or 3. Resolution was defined as return to grade 1 or 0 in all body regions. Results Of 1345 children followed for median (IQR) 5.5 (2.9, 8.2) years after ART initiation, 30 developed LA and 27 developed LH, all at least 2 years after ART initiation. Median age at LA diagnosis was 11 (10, 13) years and at LH diagnosis was 13 (11, 15) years. Children with LA were more likely white (p<0.0001); lower height-for-age z-score at ART initiation (p = 0.02); initiated ART earlier (p = 0.04), with longer ART exposure (p = 0.04). Children with LH were similar to those without. Analysis of individual drugs revealed that LA was associated with greater duration of exposure to stavudine and didanosine; while LH was associated with greater duration of exposure to stavudine and ritonavir (given alone or in combination with another protease inhibitor). Median time in follow-up following ART switch was 2.8 (1.9, 4.9) and 2.5 (1.6, 4.7) years respectively. Resolution occurred in 10 (30%) of LA cases (median time to resolution 2.3 [1.8, 3.6] years) and 3 (11%) of LH cases (median time to resolution 2.0 [1.7, 2.1] years). Conclusions Prevalence of LA and LH were low, with some resolution noted, especially for LA. More long-term data are needed.

Late-Onset Hiv Encephalopathy In Children With Long-Standing Virologic Suppression Followed By Slow Spontaneous Recovery Despite no Change In Antiretroviral Therapy: 4 Case Reports

We describe 4 Children with HIV Early Antiretroviral Therapy trial participants with late-onset HIV encephalopathy despite long-standing viral suppression in blood and undetectable HIV DNA and RNA polymerase chain reaction in cerebrospinal fluid. Extensive investigations revealed no alternative etiology. Reassuringly, all 4 experienced slow spontaneous recovery despite no change in antiretroviral therapy. Virally suppressed HIV-infected children remain at risk for fluctuating neurologic signs and symptoms.

Long-Term Changes of Subcutaneous Fat Mass in HIV-Infected Children on Antiretroviral Therapy: A Retrospective Analysis of Longitudinal Data from Two Pediatric HIV-Cohorts

Objective Longitudinal studies objectively evaluating changes in regional fat distribution of HIV-infected children assessed by whole body dual energy X-ray absorptiometry (DEXA) are scarce, whilst this long-term effect of HIV and antiretroviral therapy (cART) is an important issue in infected children in need for lifelong treatment. Methods We assessed regional fat distribution over time, measured with sequential DEXA-scans in HIV-infected children on cART in cohorts from South Africa (SA) and the Netherlands (NL), and in healthy controls (SA). Limb and trunk fat Z-scores were calculated with the lambda-mu-sigma (LMS) method. Multivariable linear regression models with mixed effects were used to investigate the effect of cART compounds on body fat distribution over time. Results In total, 218 children underwent 445 DEXA assessments with a median follow-up of 3.5 years. Fat mass in all limbs was decreased in HIV-infected children compared to controls (arm fat Z-score: coefficient -0.4813; P = 0.006, leg fat Z-score: coefficient -0.4345; P = 0.013). In the HIV-infected group, stavudine treatment was associated with lower subcutaneous fat mass (arm fat Z-score: coefficient -0.5838; P = 0.001), with an additional cumulative exposure effect (arm fat Z-score: coefficient -0.0867; P = 0.003). Conclusions Our study shows that subcutaneous fat loss is still prevalent in HIV-infected children on cART, and is strongly associated with cumulative stavudine exposure. These results underline the need for early detection of subcutaneous fat loss and alternative treatment options for HIV-infected children globally.

Delay in diagnosis of Duchenne muscular dystrophy may reduce benefit from new corticosteroid protocol

About one-third of boys with Duchenne muscular dystrophy (DMD) have associated learning difficulties, particularly speech and language delay, and this may be the initial presenting complaint. Attention is often focused on behaviour and learning difficulties, and the progressive muscle weakness may not be noticed until the condition is advanced. Now that corticosteroids have been established as the gold standard of care, delay in the diagnosis of DMD has become far more relevant because any delay may limit the benefit that can be gained from steroid therapy, since muscle strength that has been lost cannot be regained. We present 3 cases of boys with unexplained learning difficulty in whom the diagnosis could have been made far earlier if a creatine kinase test had been done at presentation.