Estimation of Height and Body Mass Index from Demi-Span in Elderly Individuals

Abstract

Background: Obtaining accurate height and, consequently, body mass index (BMI) measurements in elderly subjects can be difficult due to changes in posture and loss of height during ageing. Measurements of other body segments can be used as an alternative to estimate standing height, but population- and age-specific equations are necessary. Objective: Our objectives were to validate existing equations, to develop new simple equations to predict height in an elderly Spanish population and to assess the accuracy of the BMI calculated by estimated height from the new equations. Methods: We measured height and demi-span in a representative sample of 592 individuals, 271 men and 321 women, 65 years and older (mean ± SD, 73.8 ± 6.3 years). We suggested equations to predict height from demi-span by multiple regression analyses and performed an agreement analysis between measured and estimated indices. Results: Height estimated from demi-span correlated significantly (p < 0.001) with measured height (men: r = 0.708, women: r = 0.625). The best prediction equations were as follows: men, height (in cm) = 77.821 + (1.132 × demi-span in cm) + (–0.215 × 5-year age category); women: height (in cm) = 88.854 + (0.899 × demi-span in cm) + (–0.692 × 5-year age category). No significant differences between the mean values of estimated and measured heights were found for men (–0.03 ± 4.6 cm) or women (–0.02 ± 4.1 cm). The BMI derived from measured height did not differ significantly from the BMI derived from estimated height either. Conclusion: Predicted height values from equations based on demi-span and age may be acceptable surrogates to derive accurate nutritional indices such as the BMI, particularly in elderly populations, where height may be difficult to measure accurately.

A comparison of measured height and demi-span equivalent height in the assessment of body mass index among people aged 65 years and over in England

“…Our results from agreement analysis [22] show that BMI-DEH and BMI calculated using measured height show a closer agreement for both men and women than DEH and height measurements but results are very similar, especially for men, to a recent study [29].…”

“…Although cross-sectional surveys have shown that demi-span is also lower in older people, the difference with age is considerably less than the height measurement [3,7,29]; it is most likely to be a cohort effect reflecting the increasing height of successive cohorts during the 20th century [3,7]. It needs to be taken into account that secular trends may explain our observations, since it is difficult to show the true difference between measurements with this type of study design.…”

“…These equations are very limited since they are derived from a small sample of people and there is a need for new and potentially more robust equations to be derived from a larger dataset. Weinbrenner et al [29] derived new equations to predict height in older people based on an elderly Spanish population in whom height would be difficult to measure, however, these are population specific and so not useful for our purposes.…”

True height and variability in estimates thereof across race and gender

“…7 Although the demi-span equation was initially studied among adults as a target population, it has predominantly been studied in the elderly. 7,[48][49][50][51] In a longitudinal study, demi-span was resilient to change with increasing age. 52 However, the accuracy and precision of using the demi-span equation is affected by age-related height loss, especially among females.…”

“…52 However, the accuracy and precision of using the demi-span equation is affected by age-related height loss, especially among females. 51 Consequentially, using demi-span in the elderly results in an overestimation of BMI. 47 Adjustments to the demi-span equation have been documented, such as those 2016;29(2) S Afr J Clin Nutr developed from a health survey in England in 2007.…”