Changes in peripheral quantitative computed tomography measured bone density, size and strength in Zimbabwean children with and without HIV over one year: a cohort study.

Understanding bone accrual in adolescents may inform approaches to improve skeletal health and reduce adult fracture risk. We investigated the effect of HIV on bone mineral accrual assessed by peripheral Quantitative Computed tomography (pQCT). Children with HIV (CWH) on ART for ≥2 years, and children without HIV (CWOH), aged 8-16 years (n = 609), had tibial pQCT scans at 0 and 12 months. Linear regression estimated sex stratified differences in change (∆) and mean pQCT bone density (trabecular and cortical), size (total cross-sectional area [CSA]) and strength (SSI) between CWH and CWOH, adjusting for socio-economic status (SES) and orphanhood and incorporating an interaction term for baseline pubertal status (Tanner 1-2[pre/early] vs 3-5[mid/late]). Structural equation modelling tested whether baseline height-for-age-Z-scores (HAZ) mediate the effect of HIV on ∆bone outcomes. CWH were more likely than CWOH to be orphans (44% vs 7%), of lower SES (43% vs 27%) and be stunted (30% vs 8%); but similar in age. At baseline and follow up, CWH had lower trabecular density, CSA and SSI than CWOH. After adjustment, bone density and strength increased similarly in CWH and CWOH. CWH in mid/late puberty at baseline had greater 12 months increases in CSA than CWOH, particularly males (mean difference [31.3(95%CI:-3.1, 65.6) mm2 in mid/late puberty vs. -2.04(-23.8, 19.7) mm2 in pre/early puberty; interaction P-value = 0.013]. HAZ mediated the effect of HIV on ∆bone outcomes only in females as follows: indirect pathways from HIV to ∆trabecular density [-1.85(-3.5, -0.2) mg/cm3], ∆cortical density [-2.01(-3.9, -0.01) mg/cm3], ∆CSA [-2.59(-4.7, -0.5) mm] and ∆SSI [-18.36(-29.6, -7.2) mm3]. In conclusion, CWH show bone deficits at follow up. Investigations of bone mineral accrual earlier in life and post-puberty to peak bone mass are needed.

We measured bone density, bone size and bone strength at 0 and 12 months in 609, 8-16 year old children living with (CWH) and children living without HIV (CWOH). CWH were more likely to be orphans, to be of a lower socio-economic status, to be shorter and to have lower bone density, size and strength than CWOH who are of the same age. After 12 months, there were persistent bone deficits in CWH, despite that CWH who were in their mid/late puberty (especially males) showed greater increases in bone size than CWOH. Investigations of bone accrual in early life and beyond puberty are necessary.

Perinatal HIV infection is associated with deficits in muscle function in children and adolescents in Zimbabwe.

OBJECTIVES: To determine how muscle strength, power, mass, and density (i.e. quality) differ between children living with HIV (CWH) and those uninfected, and whether antiretroviral therapy (ART) regime is associated with muscle quality. DESIGN: A cross-sectional study in Harare, Zimbabwe. METHODS: The study recruited CWH aged 8-16 years, taking ART for at least 2 years, from HIV clinics, and HIV-uninfected children from local schools. Muscle outcomes comprised grip strength measured by hand-held Jamar dynamometer, lower limb power measured by standing long-jump distance, lean mass measured by dual-energy X-ray absorptiometry, and muscle density (reflecting intramuscular fat) by peripheral quantitative computed tomography. Linear regression calculated adjusted mean differences (aMD) by HIV status. RESULTS: Overall, 303 CWH and 306 without HIV, had mean (SD) age 12.5 (2.5) years, BMI 17.5 (2.8), with 50% girls. Height and fat mass were lower in CWH, mean differences (SE) 7.4 (1.1) cm and 2.7 (0.4)kgs, respectively. Male CWH had lower grip strength [aMD 2.5 (1.1-3.9) kg, P  < 0.001], long-jump distance [7.1 (1.8-12.5) cm, P  = 0.006], muscle density [0.58 (0.12-1.05) mg/cm 3 , P  = 0.018, but not lean mass 0.06 (-1.08 to 1.21) kg, P  = 0.891) versus boys without HIV; differences were consistent but smaller in girls. Mediation analysis suggested the negative effect of HIV on jumping power in boys was partially mediated by muscle density ( P  = 0.032). CWH taking tenofovir disoproxil fumarate (TDF) had lower muscle density [0.56 (0.00-1.13)mg/cm 3 , P  = 0.049] independent of fat mass, than CWH on other ART. CONCLUSION: Perinatally acquired HIV is associated, particularly in male individuals, with reduced upper and lower limb muscle function, not mass. Intra-muscular fat (poorer muscle quality) partially explained reductions in lower limb function. TDF is a novel risk factor for impaired muscle quality.

Wearable GPS and Accelerometer Technologies for Monitoring Mobility and Physical Activity in Neurodegenerative Disorders: A Systematic Review.

Neurodegenerative disorders (NDDs) constitute an increasing global burden and can significantly impair an individual's mobility, physical activity (PA), and independence. Remote monitoring has been difficult without relying on diaries/questionnaires which are more challenging for people with dementia to complete. Wearable global positioning system (GPS) sensors and accelerometers present a cost-effective and noninvasive way to passively monitor mobility and PA. In addition, changes in sensor-derived outcomes (such as walking behaviour, sedentary, and active activity) may serve as potential biomarkers of disease onset, progression, and response to treatment. We performed a systematic search across four databases to identify papers published within the past 5 years, in which wearable GPS or accelerometers were used to monitor mobility or PA in patients with common NDDs (Parkinson's disease, Alzheimer's disease, motor neuron diseases/amyotrophic lateral sclerosis, vascular parkinsonism, and vascular dementia). Disease and technology-specific vocabulary were searched singly, and then in combination, identifying 4985 papers. Following deduplication, we screened 3115 papers and retained 28 studies following a full text review. One study used wearable GPS and accelerometers, while 27 studies used solely accelerometers in NDDs. GPS-derived measures had been validated against current gold standard measures in one Parkinson's cohort, suggesting that the technology may be applicable to other NDDs. In contrast, accelerometers are widely utilised in NDDs and have been operationalised in well-designed clinical trials.