Table 5.
Association of traditional anion gap, albumin-corrected anion gap, full anion gap, and serum bicarbonate with all-cause mortality in United States adults with moderate chronic kidney disease (n = 1,145) with a followup of 12 yr using a frailty model
| Relative Hazard for Mortality (95% Confidence Interval)a |
|||
|---|---|---|---|
| Model | Lowest tertile | Middle tertile | Highest tertile |
| Traditional anion gap | (minimal−8.1 meq/l) | (8.1–11.8 meq/l) | (11.8−maximal meq/l) |
| Unadjusted | 1.05 (0.92–1.18) | 1.0 (reference) | 1.28 (1.14–1.43) |
| Adjustedb | 0.97 (0.84–1.09) | 1.0 (reference) | 1.16 (0.99–1.32) |
| Fully adjustedc | 0.91 (0.78–1.06) | 1.0 (reference) | 1.18 (0.98–1.40) |
| Albumin-corrected anion gap | (minimal−9.2 meq/l) | (9.2–12.7 meq/l) | (12.7−maximal meq/l) |
| Unadjusted | 1.10 (1.00–1.21) | 1.0 (reference) | 1.25 (1.08–1.42) |
| Adjustedb | 1.01 (0.87–1.15) | 1.0 (reference) | 1.14 (0.97–1.30) |
| Fully adjustedd | 0.98 (0.81–1.10) | 1.0 (reference) | 1.13 (0.95–1.31) |
| Full anion gap | (minimal−15.93 meq/l) | (15.93–19.54 meq/l) | (19.54−maximal meq/l) |
| Unadjusted | 1.11 (0.96–1.25) | 1.0 (reference) | 1.23 (1.06–1.39) |
| Adjustedb | 1.04 (0.90–1.19) | 1.0 (reference) | 1.15 (0.99–1.32) |
| Fully adjusted d | 1.01 (0.85–1.16) | 1.0 (reference) | 1.20 (1.01–1.39) |
| Serum bicarbonate | (minimal−26 mmol/l) | (26–29 mmol/l) | (29−maximal mmol/l) |
| Unadjusted | 0.89 (0.89–1.00) | 1.0 (reference) | 0.97 (0.83–1.11) |
| Adjustedb | 0.95 (0.83–1.07) | 1.0 (reference) | 0.99 (0.84–1.13) |
| Fully adjusted e | 0.98 (0.80–1.15) | 1.0 (reference) | 1.01 (0.70–1.31) |
Moderate chronic kidney disease was defined as an estimated glomerular filtration rate of 30–59 ml·min−1·1.73 m−2. These linkage data were limited to linkage-eligible participants. All analyses included the total third National Health and Nutrition Evaluation Survey (NHANES III) MEC-examined sample final weight to account for the complex sample design following the analytical guidelines for NHANES III data (32). For variance estimates, we used Fay’s balanced repeated replication procedure, an approach for estimation of standard errors for multistage samples that consists of many sampling units. aFrom the frailty model; badjusted for demographic factors (age, sex, and race), diabetes, hypertension, estimated glomerular filtration rate, and urinary albumin-to-creatinine ratio. cadjusted for demographic factors (age, sex, and race), diabetes, hypertension, estimated glomerular filtration rate, urinary albumin-to-creatinine ratio, body mass index, serum albumin, total protein, and serum bicarbonate; dadjusted for demographic factors (age, sex, and race), diabetes, hypertension, estimated glomerular filtration rate, urinary albumin-to-creatinine ratio, body mass index, serum total protein, and serum bicarbonate; eadjusted for demographic factors (age, sex, and race), diabetes, hypertension, estimated glomerular filtration rate, urinary albumin-to-creatinine ratio, body mass index, and serum anion gap.