Measurement error from assessing use of vitamin supplements at one point in time.
Although many epidemiologic studies ask about current use of vitamin supplements, long-term use is usually the exposure of etiologic interest. We conducted a mailed survey to investigate the relation between current and long-term (10-year) supplement use (N = 325 adults). Estimates of current daily intake for supplemental micronutrients were roughly twice that of average daily intake over the past 10 years. Correlations between current intake and long-term intake from supplements alone were 0.77, 0.75, and 0.65 for vitamin C, vitamin E, and calcium, respectively. A measure of supplement use at one point in time incorporates measurement error that will attenuate measures of association.
Patterson
R E
RE
Fred Hutchinson Cancer Research Center, and Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, Seattle 98109-1024, USA.
Neuhouser
M L
ML
White
E
E
Kristal
A R
AR
Potter
J D
JD
D000368:Aged; D004032:Diet / Q000706:statistics & numerical data; D019587:Dietary Supplements / Q000706:statistics & numerical data*; D015991:Epidemiologic Measurements; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D011897:Random Allocation; D011795:Surveys and Questionnaires; D014815:Vitamins / Q000008:administration & dosage*; D014861:Washington / Q000453:epidemiology
D014815:Vitamins