Agreement between measured height, and height predicted from ulna length, in adult patients in Bloemfontein, South Africa

Abstract

Objective: To assess the agreement between measured height, and height predicted from ulna length using the Malnutrition Universal Screening Tool (MUST) equations, in adult patients admitted to government hospitals in Bloemfontein, South Africa. Design: Descriptive cross-sectional survey. Setting: Medical, surgical, pulmonary, orthopaedic, cardiovascular and general wards at Pelonomi, Universitas and National Hospitals in Bloemfontein. Subjects: All patients between 19 and 60 years, admitted during a two-week period in March 2015, who gave written informed consent, and were able to stand upright and unassisted, were included. Outcome measures: Standing height (via stadiometer; referred to as reference height), weight and ulna length were measured. Predicted height and body mass index (BMI) were calculated from ulna length using MUST equations, and compared with reference height and BMI by 95% confidence intervals (CI) and Bland–Altman analysis. Results: The sample comprised n = 200 participants (48% female; median age: 42 years: 32–51 years). The median height estimated from ulna length (170.2 cm; range: 154.2–213.0 cm) was statistically significantly (95% CI [7.1; 7.7]) longer than the median reference height (163.9 cm; range: 145.1–188.4 cm). The Bland–Altman analysis indicated that the 95% limits of agreement between the two methods ranged from –19.8 to 5.7 cm. Median BMI based on estimated height (20.1 kg/m2) was significantly (95% CI [–1.9; –1.6]) lower than median BMI calculated from reference height (21.8 kg/m2). Conclusion: Height predicted from ulna length with the MUST equations overestimated height in this population. This may be related to high prevalence of stunting in the South African population. The discrepancy may have clinical implications particularly for critically ill patients. Strong message: Estimations of height based on upper body long-bone measurements may not be reliable in populations with a high prevalence of stunting.