Stature prediction from knee height in Chinese elderly subjects

Abstract

Knee height (KH) measurement is a recumbent anthropometric technique for the estimation of stature in nonambulatory elders. Based on the estimated stature, body mass index (BMI) could be derived for nutritional status assessment. The objective of this study was to verify the KH equations of Chumlea et al. (J Am Geriatr Soc 33:116-120, 1985) and if necessary develop population specific equations. Knee height calipers (Ross Laboratory) and a stadiometer were used to measure KH and stature in a group of institutionalized elders (26 males and 21 females) Differences between measured stature and calculated estimates using the Chumlea equation were -1.7 cm for females (t=2.43, P<0.025) and 0.8 cm for males (t=0.89, ns). In view of the significant deviations found in females, another study was initiated to generate population specific knee height equations. The age range of these newly recruited elders was 60 to 97 years old. Only elders who can stand fully erect are included (62 females and 89 males). Age and KH were independent variables in the stepwise regression analyses. When the first group of elders were used to verify the current gender specific equations, the mean differences were 0.5 cm for females (t=0.8, ns) and - 0.3 cm for males (t= 0.53, ns). Similar effects were obtained when BMI was calculated based on estimated stature. It is concluded that the Chumlea equation gives good stature estimates on Chinese males. The new knee height equation will better predict stature in Chinese female elders.