Total body and hand surface area: Measurements, calculations, and comparisons in ethnically diverse children in South Africa.

Aim: The aim was to investigate hand surface as a percentage of body surface area from infancy to 13 years of age using physical measurement and digital planimetry and establish the influence of age, gender, BMI for age and ethnicity, specifically in the South African population. A secondary aim included the development of a template for burn size measurement.

Methodology: This was a cross-sectional observational study. Demographic information was obtained from each participant. Body mass index (BMI) and body surface area (BSA) were determined using several established formulas. The hand area was measured using a standard physical measurement method and a digital planimetry method. All data was presented in an Excel and SPSS spreadsheet and the calculations performed with SPSS 24.0.

Results: Three-hundred and sixty-eight burn patients and 150 children from a nearby primary school were enrolled. The age ranged from 1 month to 13 years. The hospital patient group was significantly younger, included more boys and had a lower BMI by age. Most patients (98.7%) were African or mixed race compared to the school children who were primarily Caucasian (p<0.001). The seven formulas to determine the BSA were highly comparable with Intraclass correlation coefficient (ICC) of 0.997 (95% CI 0.996-0.998). Actual hand surface area measured ranged from 22.44cm to 164.9cm. The mean measured and digital percentage HSA of TBSA for all participants was 0.929% with a SD of 0.088. Male children, had a larger HSA as a proportion of TBSA by 0.036%. Generally, as the child gets older from toddler to late childhood, the hand becomes relatively smaller by a factor of approximately 0.08%. As the BMI increased, the hand got relatively smaller.

Conclusion: The potential value of the physical measurement method is that it lends itself to direct measurement during examination of the burnt child. The study showed that there are minor differences between racial groups, gender, BMI and age variations. The clinical relevance of these variations is negligible.