Agreement between self-reported and measured height, weight and body mass index in old age--a longitudinal study with 20 years of follow-up.
BACKGROUND
self-reported body mass index (BMI) based on self-reported height and weight is a widely used measure of adiposity in epidemiological research. Knowledge about the accuracy of these measures in late life is scarce.


OBJECTIVE
the study aimed to evaluate the accuracy and changes in accuracy of self-reported height, weight and BMI calculated from self-reported height and weight in late life.


METHODS
a longitudinal population-based study with five times of follow-up was conducted.


METHODS
seven hundred seventy-four community-living men and women, aged 40-88 at baseline (mean age 63.9), included in The Swedish Adoption/Twin Study of Aging.


METHODS
participants self-reported their height and weight in a questionnaire, and height and weight were measured by experienced research nurses at an in-person testing five times during a 20-year period. BMI was calculated as weight (kilogramme)/height (metre)(2).


RESULTS
latent growth curve modelling showed an increase in the mean difference between self-reported and measured values over time for height (0.038 cm/year) and BMI (0.016 kg/m(2)/year), but not for weight.


CONCLUSIONS
there is a very small increase in the mean difference between self-reported and measured BMI with ageing, which probably would not affect the results when self-reported BMI is used as a continuous variable in longitudinal studies.
Dahl
Anna K
AK
Institute of Gerontology, Jönköping University, Sweden. anna.dahl@hhj.hj.se <anna.dahl@hhj.hj.se>
Hassing
Linda B
LB
Fransson
Eleonor I
EI
Pedersen
Nancy L
NL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D005500:Follow-Up Studies; D015577:Geriatric Assessment / Q000706:statistics & numerical data*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012649:Self Concept; D011795:Surveys and Questionnaires
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