Table 1

Baseline characteristics of patients with low serum bicarbonate level in comparison with those of control group
All Low-bicarbonate group Control group p value
N (%) 113 28 85
Age (years) 70.4 ± 6.6 71.0 ± 6.9 70.2 ± 6.5 0.59
Female (%) 41 (36.3) 5 (17.9) 36 (42.4) 0.019
Diabetes mellitus (%) 38 (33.6) 5 (17.9) 33 (38.8) 0.042
Hypertension (%) 45 (39.8) 3 (10.7) 42 (49.4) 0.0003
Height (cm) 160.6 ± 8.9 164.8 ± 8.1 159.2 ± 8.7 0.005
Weight (kg) 58.3 ± 8.9 60.9 ± 9.4 57.4 ± 8.6 0.08
BMI (kg/m2) 22.5 ± 2.5 22.3 ± 2.2 22.6 ± 2.5 0.61
eGFR (ml/min/1.73 m2) 25.7 ± 13.6 15.1 ± 5.9 29.1 ± 13.6 0.0001
CKD Stage (%) 0.0001
3 40 (35.4) 1 (3.5) 39 (45.9)
4 44 (38.9) 12 (42.9) 32 (37.7)
5 29 (25.7) 15 (53.6) 14 (16.5)
Albumin level (g/dl) 3.7 ± 0.3 3.7 ± 0.3 3.7 ± 0.4 0.99
Sodium level (mEq/l) 140.7 ± 2.3 140.9 ± 2.2 140.7 ± 2.4 0.63
Potassium level (mEq/l) 4.8 ± 0.5 5.0 ± 0.5 4.7 ± 0.5 0.004
Bicarbonate level (mEq/l) 27.4 ± 3.2 23.4 ± 1.8 28.8 ± 2.3 0.0001
24-hour urine protein excretion level (g/day) 0.93 ± 1.01 1.25 ± 1.19 0.83 ± 0.93 0.063
0.52 (IQR, 0.25, 1.18) 1.04 (IQR, 0.35, 1.66) 0.44 (IQR, 0.24, 1.11)
RAAS inhibitor use (%) 98 (86.7) 20 (71.4) 78 (91.8) 0.006
ACEI use 51 (45.1) 12 (42.9) 39 (45.9)
ARB use 86 (76.1) 18 (64.3) 68 (80.0)
Direct renin inhibitor use 34 (30.4) 9 (32.1) 25 (29.8)
Loop diuretic use (%) 37 (32.7) 11 (39.3) 26 (30.6) 0.40
Sodium bicarbonate use (%) 23 (20.3) 12 (42.9) 11 (12.9) 0.0006
Dose of sodium bicarbonate (g/day) 0.54 ± 1.29 1.28 ± 2.03 0.28 ± 0.78 0.0006
0 (IQR, 0, 0) 0 (IQR, 0, 2) 0 (IQR, 0, 0)
Decrease of 25% or more in eGFR (%) 46 (40.7) 19 (67.9) 27 (31.8) 0.0007
Dialysis (%) 10 (8.9) 6 (21.4) 4 (4.7) 0.007
Outcome (%) 46 (40.7) 19 (67.9) 27 (31.8) 0.0007
Follow-up days (days) 449.3 ± 162.7 360.4 ± 184.6 478.6 ± 144.4 0.0007

Values are expressed as mean ± standard deviation. The levels of 24-hour urine protein excretion and dose of sodium bicarbonate are presented with median and IQR. The values are compared between the groups by the chi-square test, t-test, or Mann–Whitney U-test as appropriate.

Abbreviations: BMI Body mass index, eGFR Estimated glomerular filtration rate, RAAS Renin angiotensin aldosterone system, ACEI Angiotensin-converting enzyme inhibitor, ARB Angiotensin II receptor blocker, IQR Interquartile range; outcome, a decrease of 25% or higher in eGFR or starting dialysis.

Kanda et al.

Kanda et al. BMC Nephrology 2013 14:4   doi:10.1186/1471-2369-14-4

Open Data