Chia-Yih Wang1, Alicia L Carriquiry2, Te-Ching Chen3, Catherine M Loria4, Christine M Pfeiffer5, Kiang Liu6, Christopher T Sempos7, Cria G Perrine8, Mary E Cogswell9. 1. Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, CDC, Hyattsville, MD; cwang@cdc.gov. 2. Department of Statistics, Iowa State University, Ames, IA; 3. Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, CDC, Hyattsville, MD; 4. National Heart, Lung, and Blood Institute, and. 5. Division of Laboratory Sciences, National Center for Environmental Health. 6. Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL. 7. Office of Dietary Supplements, NIH, Bethesda, MD; 8. Division of Nutrition, Physical Activity, and Obesity, and. 9. Division for Heart Disease and Stroke Prevention, National Center for Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA; and.
Abstract
BACKGROUND: High US sodium intake and national reduction efforts necessitate developing a feasible and valid monitoring method across the distribution of low-to-high sodium intake. OBJECTIVE: We examined a statistical approach using timed urine voids to estimate the population distribution of usual 24-h sodium excretion. METHODS:A sample of 407 adults, aged 18-39 y (54% female, 48% black), collected each void in a separate container for 24 h; 133 repeated the procedure 4-11 d later. Four timed voids (morning, afternoon, evening, overnight) were selected from each 24-h collection. We developed gender-specific equations to calibrate total sodium excreted in each of the one-void (e.g., morning) and combined two-void (e.g., morning + afternoon) urines to 24-h sodium excretion. The calibrated sodium excretions were used to estimate the population distribution of usual 24-h sodium excretion. Participants were then randomly assigned to modeling (n = 160) or validation (n = 247) groups to examine the bias in estimated population percentiles. RESULTS: Median bias in predicting selected percentiles (5th, 25th, 50th, 75th, 95th) of usual 24-h sodium excretion with one-void urines ranged from -367 to 284 mg (-7.7 to 12.2% of the observed usual excretions) for men and -604 to 486 mg (-14.6 to 23.7%) for women, and with two-void urines from -338 to 263 mg (-6.9 to 10.4%) and -166 to 153 mg (-4.1 to 8.1%), respectively. Four of the 6 two-void urine combinations produced no significant bias in predicting selected percentiles. CONCLUSIONS: Our approach to estimate the population usual 24-h sodium excretion, which uses calibrated timed-void sodium to account for day-to-day variation and covariance between measurement errors, produced percentile estimates with relatively low biases across low-to-high sodium excretions. This may provide a low-burden, low-cost alternative to 24-h collections in monitoring population sodium intake among healthy young adults and merits further investigation in other population subgroups.
RCT Entities:
BACKGROUND: High US sodium intake and national reduction efforts necessitate developing a feasible and valid monitoring method across the distribution of low-to-high sodium intake. OBJECTIVE: We examined a statistical approach using timed urine voids to estimate the population distribution of usual 24-h sodium excretion. METHODS: A sample of 407 adults, aged 18-39 y (54% female, 48% black), collected each void in a separate container for 24 h; 133 repeated the procedure 4-11 d later. Four timed voids (morning, afternoon, evening, overnight) were selected from each 24-h collection. We developed gender-specific equations to calibrate total sodium excreted in each of the one-void (e.g., morning) and combined two-void (e.g., morning + afternoon) urines to 24-h sodium excretion. The calibrated sodium excretions were used to estimate the population distribution of usual 24-h sodium excretion. Participants were then randomly assigned to modeling (n = 160) or validation (n = 247) groups to examine the bias in estimated population percentiles. RESULTS: Median bias in predicting selected percentiles (5th, 25th, 50th, 75th, 95th) of usual 24-h sodium excretion with one-void urines ranged from -367 to 284 mg (-7.7 to 12.2% of the observed usual excretions) for men and -604 to 486 mg (-14.6 to 23.7%) for women, and with two-void urines from -338 to 263 mg (-6.9 to 10.4%) and -166 to 153 mg (-4.1 to 8.1%), respectively. Four of the 6 two-void urine combinations produced no significant bias in predicting selected percentiles. CONCLUSIONS: Our approach to estimate the population usual 24-h sodium excretion, which uses calibrated timed-void sodium to account for day-to-day variation and covariance between measurement errors, produced percentile estimates with relatively low biases across low-to-high sodium excretions. This may provide a low-burden, low-cost alternative to 24-h collections in monitoring population sodium intake among healthy young adults and merits further investigation in other population subgroups.
Authors: Kirsten Bibbins-Domingo; Glenn M Chertow; Pamela G Coxson; Andrew Moran; James M Lightwood; Mark J Pletcher; Lee Goldman Journal: N Engl J Med Date: 2010-01-20 Impact factor: 91.245