**Background:** There is a critical gap in school-age health outcome data for children aged 5-14 years in low- and middle-income countries (LMICs), a period termed the 'missing middle' of child health. Existing tools rarely combine growth, physical function, and cognitive function assessments holistically. The authors developed the School-Age Health, Activity, Resilience, Anthropometry and Neurocognitive (SAHARAN) toolbox to address this need, with three objectives: develop and test feasibility, describe a pilot cohort, and explore associations between domains.
**Methods:** The toolbox was developed through a systematic process including literature review, expert consultation, COSMIN-based tool selection, cognitive interviewing, and pre-testing. The final battery comprised: growth assessment (anthropometry, knee-heel length, skinfold thicknesses), body composition (bioimpedance analysis for lean mass index and phase angle), cognitive function (KABC-II mental processing index [MPI], School Achievement Test [SAT], fine motor finger-tapping task, Strengths and Difficulties Questionnaire [SDQ]), and physical function (handgrip strength, broad jump, 20m shuttle-run test combined into a total physical score). A caregiver questionnaire captured demographics, adversities, food security, and socioemotional factors. The pilot was conducted in Zvamabande (rural) and Makusha (urban) in Shurugwi district, Zimbabwe. Of 157 eligible children aged 7 years, 80 were randomly selected and assessed between September 3rd and December 4th, 2020. Assessments took 4-5 hours per child. Growth measurements were converted to WHO Z-scores. Associations were explored using least squares regression.
**Key Results:** The toolbox was feasible and acceptable after minor modifications (replacing electronic blood pressure cuffs with manual sphygmomanometers, adapting two KABC-II subtests for rural context, replacing the Early Grade Reading Assessment with a culturally adapted SAT). All 80 children (39 girls, 49%) completed the full battery. Mean (SD) age was 7.6 (0.2) years. Mean HAZ was -0.63 (0.81) and mean WAZ was -0.55 (0.85); 2 children (3%) were stunted and 3 (4%) were underweight. Mean BMI was 15.3 kg/m² (SD 1.4). Mean handgrip strength was 12 Kg (SD 2), mean broad jump distance was 111 cm (SD 16), and mean shuttle-run level was 3.4 (SD 1.2). Mean haemoglobin was 126 g/L (SD 10.1); 5 children (6%) were below the WHO anaemia threshold of 110 g/L. Mean MPI was 47 (SD 9), mean SAT score was 41 (SD 21), mean fastest finger tapping time was 22 (SD 6) seconds, and mean SDQ total difficulties score was 10 (SD 5). Eighteen children (23%) could not recognise any letters and 9 (11%) could not write any letters. The adversity questionnaire revealed a mean of 5 (SD 3.1) adverse events per household since the child's birth; 75% reported crop failure, 50% business failure, 34% loss of possessions, and 33% household death. Only 19% of children were enrolled in school during the COVID-19-affected academic year. Total physical score was significantly associated with HAZ (1.29, 95% CI 0.75, 1.82, p<0.001), lean mass index (0.50, 95% CI 0.16, 0.83, p=0.004), and WAZ, but not with skinfold thicknesses or waist circumference. The SAT was associated with each additional year of schooling and with the child's perceived socioemotional support score. The MPI was associated with SAT and weakly with fine motor skills, but not with HAZ or head circumference. Higher phase angle was significantly associated with faster fine motor completion time.
**Clinical Implications:** The SAHARAN toolbox provides a portable, holistic assessment battery suitable for school-age children in LMICs. The strong associations between linear growth, lean mass, and physical function suggest that promoting early-life linear growth and lean mass accretion may improve later physical function and potentially reduce chronic disease risk. The lack of association between growth and cognitive function reinforces that growth is a poor proxy for cognition, and direct cognitive assessment is essential. The high prevalence of household adversities (mean 5 events in 7 years) and food insecurity (median HFIAS 6) highlights the challenging environments in which children in rural Zimbabwe develop. The toolbox can now be deployed in larger cohorts and trials to evaluate early-life interventions on school-age outcomes.