Equations suggested by WHO to estimate height above 60 years of age do not fit Portuguese elderly: A new predictive model based on knee height

Aged individuals present a high prevalence of health problems that unable the correct measuring of height (e.g.: incapacity to stand up, spine deformities, inferior limb deformities, prosthesis and amputations). In populations 60 years of age or older not studied on predicting height, the World Health Organization suggests the use of Chumlea's 1992 equations, developed in United States and based on knee height, gender and age. These equations may not be applicable in other populations, as showed in Mexico. The study assessed 299 healthy Caucasian Portuguese aged 60 to 95. Data on gender, age, height and knee height were collected. Measurements were taken with a vertical stadiometer, as in the original study. The subjects studied presented an average age of 78.3 (SD = 8.9) for men and 73.5 (SD = 8.5) for women and average stature of 162.4 cm (SD = 6.0) for men and 152.2 cm (SD = 5.6) for women. Height and knee height showed strong correlations (Pearson 0.786 in men and 0.694 in women; P < 0.001). Our subjects were older and shorter than the ones in the original study. Chumlea's equations overestimated height 4.07 cm for men and 1.58 cm for women (P < 0.001). Although this study presents several limitations, the Chumlea's equations do not appear to be applicable to elderly Portuguese. A new predictive model was developed using multiple regression models. The equations obtained were (in cm): standing height (men) = 77.61 + 1.64 knee height; standing height (women) = 73.77 + 1.64 knee height. This model showed R2 of 0.698 for women and 0.737 for men.