title: Measures of body mass and of obesity from infancy to adulthood and their appropriate transformation.
abstract: In this paper we investigate first the choice of an appropriate index of body mass. The traditional indices weight/height (W/H), W/H2 and W/H3 are compared, as well as an approach due to Cole (1986) making the index W/Hp age-dependent, i.e. by allowing the power p to depend on age. While there may be no perfect index reflecting over- and underweight--irrespective of height and width--the Quetelet index W/H2 turned out to be a reasonable index from childhood to adulthood. Second, we study the development of the body mass index W/H2 longitudinally from birth onwards, based on structural average distance, velocity and acceleration curves. As a third topic, transformations for obtaining an approximate normal distribution for W/H2, weight and skinfolds are compared. The usual log-transformation turned out to be unsatisfactory. While for height and arm skinfolds a transformation -1/square root of x performs rather well across age and sex, a transformation -1/x is more appropriate for trunk skinfolds and W/H2.
authors.affiliation: Abteilung Biostatistik, Universität Zürich, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Gasser
authors.forename: P
authors.initials: P
authors.lastname: Ziegler
authors.forename: B
authors.initials: B
authors.lastname: Seifert
authors.forename: A
authors.initials: A
authors.lastname: Prader
authors.forename: L
authors.initials: L
authors.lastname: Molinari
authors.forename: R
authors.initials: R
authors.lastname: Largo
mesh_terms: D000367:Age Factors; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D005500:Follow-Up Studies; D006128:Growth; D006801:Humans; D008297:Male; D016011:Normal Distribution; D009765:Obesity / Q000503:physiopathology*; D012885:Skinfold Thickness