Variation in Urinary Flow Rates According to Demographic Characteristics and Body Mass Index in NHANES: Potential Confounding of Associations between Health Outcomes and Urinary Biomarker Concentrations

http://dx.doi.org/10.1289/ehp.1408944



Table 3. GM UFRBW (mL/hr-kg) from NHANES 2009–2012 by age group, sex, race/ethnic group, and BMI categories.
Mean 6–11 years 12–19 years 20–39 years 40–59 years ≥ 60 years
GM (95% CI) p-Valuea GM (95% CI) p-Valuea GM (95% CI) p-Valuea GM (95% CI) p-Valuea GM (95% CI) p-Valuea
ap-Values present comparison with reference group within each age stratum for each categorization (sex, race/ethnic group, or BMI category), except as otherwise indicated. bCompared with ages 20–39 years.
All 1.01 (0.95, 1.07) < 0.001b 0.67 (0.63, 0.70) 0.5b 0.65 (0.62, 0.69) Reference 0.64 (0.62, 0.66) 0.4b 0.56 (0.53, 0.58) < 0.001b
Sex
Male (reference) 1.04 (0.97, 1.11) Reference 0.66 (0.61, 0.71) Reference 0.64 (0.61, 0.67) Reference 0.62 (0.59, 0.65) Reference 0.56 (0.53, 0.59) Reference
Female 0.98 (0.89, 1.07) 0.3 0.67 (0.63, 0.72) 0.7 0.66 (0.61, 0.72) 0.3 0.66 (0.63, 0.68) 0.04 0.55 (0.52, 0.59) 0.7
Race/ethnic group
Mexican American 0.94 (0.85, 1.03) 0.02 0.67 (0.62, 0.72) 0.5 0.57 (0.53, 0.62) < 0.001 0.55 (0.51, 0.60) < 0.001 0.49 (0.43, 0.56) 0.05
Non-Hispanic White 1.08 (0.98, 1.19) Reference 0.70 (0.64, 0.75) Reference 0.71 (0.66, 0.75) Reference 0.67 (0.64, 0.70) Reference 0.57 (0.54, 0.60) Reference
Non-Hispanic Black 0.87 (0.78, 0.97) 0.005 0.55 (0.51, 0.59) < 0.001 0.46 (0.43, 0.49) < 0.001 0.49 (0.46, 0.51) < 0.001 0.47 (0.44, 0.49) < 0.001
Other 1.09 (0.95, 1.25) 0.9 0.72 (0.64, 0.82) 0.6 0.75 (0.69, 0.83) 0.1 0.75 (0.65, 0.87) 0.1 0.61 (0.52, 0.71) 0.3
BMI
< 20 (reference) 1.12 (1.05, 1.21) Reference 0.84 (0.77, 0.91) Reference 0.87 (0.75, 1.00) Reference 1.06 (0.86, 1.31) Reference 0.80 (0.68, 0.95) Reference
20 to < 25 0.85 (0.75, 0.96) < 0.001 0.69 (0.64, 0.74) < 0.001 0.81 (0.75, 0.87) 0.4 0.87 (0.80, 0.95) 0.06 0.66 (0.60, 0.73) 0.04
25 to < 30 0.65 (0.57, 0.75) < 0.001 0.57 (0.52, 0.63) < 0.001 0.66 (0.61, 0.72) 0.004 0.66 (0.62, 0.70) < 0.001 0.59 (0.55, 0.64) 0.004
≥ 30 0.43 (0.35, 0.52) < 0.001 0.46 (0.41, 0.51) < 0.001 0.49 (0.46, 0.52) < 0.001 0.48 (0.46, 0.50) < 0.001 0.45 (0.43, 0.48) < 0.001