Longitudinal change in height of men and women: Implications for interpretation of the body mass index - The Baltimore Longitudinal Study of Aging

Age differences in height derived from cross-sectional studies can be the r esult of differential secular influences among the age cohorts. To determin e the magnitude of height loss that accompanies aging, longitudinal studies are required. The authors studied 2,084 men and women aged 17-94 years enr olled from 1958 to 1993 in the Baltimore Longitudinal Study of Aging, Balti more, Maryland. On average, men's height was measured nine times during 15 years and women's height five times during 9 years. The rate of decrease in height was greater for women than for men. For both sexes, height loss beg an at about age 30 years and accelerated with increasing age. Cumulative he ight loss from age 30 to 70 years averaged about 3 cm for men and 5 cm for women; by age 80 years, it increased to 5 cm for men and 8 cm for women. Th is degree of height loss would account for an "artifactual" increase in bod y mass index of approximately 0.7 kg/m(2) for men and 1.6 kg/m(2) for women by age 70 years that increases to 1.4 and 2.6 kg/m(2), respectively, by ag e 80 years. True height loss with aging must be taken into account when hei ght (or indexes based on height) is used in physiologic or clinical studies .