Table 4.

Association of net endogenous acid production with serum bicarbonate within age categories

Net Endogenous Acid ProductionCoefficient (95% Confidence Interval)
Model 1Model 2Model 3
Age 20–39 yr (n=3299)
 Continuousa−0.05 (−0.14 to 0.03)−0.12 (−0.20 to −0.03)b−0.07 (−0.16 to 0.01)
 <39.3 mEq/dReferenceReferenceReference
 39.3–52.9 mEq/d−0.10 (−0.42 to 0.21)−0.17 (−0.49 to 0.14)−0.12 (−0.42 to 0.18)
 53.0–69.9 mEq/d−0.14 (−0.48 to 0.20)−0.27 (−0.56 to 0.02)−0.15 (−0.40 to 0.11)
 ≥70.0 mEq/d−0.25 (−0.51 to 0.02)−0.40 (−0.64 to −0.17)b−0.26 (−0.49 to −0.03)b
 P for trend0.050.0010.03
Age 40–59 yr (n=3139)
 Continuousa−0.29 (−0.39 to −0.19)b−0.33 (−0.43 to −0.23)b−0.26 (−0.37 to −0.16)b
 <39.3 mEq/dReferenceReferenceReference
 39.3–52.9 mEq/d−0.03 (−0.34 to 0.28)−0.13 (-0.43 to 0.17)−0.11 (−0.40 to 0.18)
 53.0–69.9 mEq/d−0.36 (−0.65 to −0.08)b−0.42 (−0.69 to −0.14)b−0.35 (−0.63 to −0.07)b
 ≥70.0 mEq/d−0.64 (−0.96 to −0.32)b−0.76 (−1.08 to −0.43)b−0.60 (−0.92 to −0.29)b
P for trend<0.001<0.001<0.001
Age≥60 yr (n=3343)
 Continuousa−0.21 (−0.35 to −0.07)b−0.20 (−0.34 to −0.06)b−0.17 (−0.30 to −0.04)b
 <39.3 mEq/dReferenceReferenceReference
 39.3–52.9 mEq/d−0.11 (−0.38 to 0.16)−0.10 (−0.37 to 0.18)−0.11 (−0.39 to 0.17)
 53.0–69.9 mEq/d−0.22 (−0.50 to 0.06)−0.18 (−0.45 to 0.09)−0.15 (−0.40 to 0.09)
 ≥70.0 mEq/d−0.58 (−0.93 to −0.23)b−0.55 (−0.90 to −0.19)b−0.49 (−0.84 to −0.14)b
 P for trend0.0020.0040.008
  • Model 1: unadjusted. Model 2: adjusted for age, sex, and race/ethnicity. Model 3: model 2 adjusted for body mass index, poverty, education, smoking status, diuretic use, diagnosis of diabetes mellitus, hypertension, cardiovascular disease, estimated GFR, log-transformed urine albumin–creatinine ratio, serum albumin, and log-transformed C-reactive protein. P for interaction by age=0.005.

  • a Per SD higher net endogenous acid production (SD=26.4 mEq/d).

  • b P<0.05.