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Table 1 Study Cohort Characteristics

From: Metabolic acidosis is associated with increased risk of adverse kidney outcomes and mortality in patients with non-dialysis dependent chronic kidney disease: an observational cohort study

  Total Study Cohort
N = 51,558
Metabolic Acidosis Group
N = 17,350
Normal Serum Bicarbonate Group
N = 34,208
P value
Sex, n (%)
 Female 27,094 (53) 9,011 (52) 18,083 (53) 0.047
 Male 24,464 (47) 8,339 (48) 16,125 (47) 0.047
 Age, mean ± SD 72.9 ± 11.5 70.3 ± 13.3 74.3 ± 10.3 < 0.001
Race, n (%)
 African American 5,128 (10) 2,585 (15) 2,543 (7) < 0.001
 Asian 996 (2) 398 (2) 598 (2) < 0.001
 Caucasian 42,055 (82) 12,866 (74) 29,189 (85) < 0.001
 Other/unknown 3,379 (7) 1,501 (9) 1,878 (5) < 0.001
Region, n (%)
 Midwest 30,683 (60) 9,359 (54) 21,324 (62) < 0.001
 Northeast 2,603 (5) 1,175 (7) 1,428 (4) < 0.001
 Other/unknown 586 (1) 227 (1) 359 (1) 0.009
 South 14,107 (27) 5,329 (31) 8,778 (26) < 0.001
 West 3,579 (7) 1,260 (7) 2,319 (7) 0.041
Baseline labs, mean ± SD
 Serum bicarbonate, mEq/L 24.0 ± 3.6 19.7 ± 1.1 26.1 ± 2 < 0.001
 eGFR, mL/min/1.73 m2 41.2 ± 12.1 37.2 ± 13.3 43.2 ± 10.9 < 0.001
 ACR, urinary, mg/g 190 ± 554 277 ± 692 127 ± 414 < 0.001
CKD stage, n (%)
 Stage 3a 22,431 (44) 5,719 (33) 16,712 (49) < 0.001
 Stage 3b 19,081 (37) 5,987 (35) 13,094 (38) < 0.001
 Stage 4 8,736 (17) 4,747 (27) 3,989 (12) < 0.001
 Stage 5, non-dialysis 1,310 (3) 897 (5) 413 (1) < 0.001
Comorbidities/conditions, n (%)
 Hypertension 31,761 (62) 12,879 (74) 18,882 (55) < 0.001
 Diabetes 16,168 (31) 7,391 (43) 8,777 (26) < 0.001
 Coronary artery disease 14,329 (28) 6,249 (36) 8,080 (24) < 0.001
 Peripheral vascular disease 10,052 (19) 5,038 (29) 5,014 (15) < 0.001
 Heart failure 10,029 (19) 5,119 (30) 4,910 (14) < 0.001
 CCI, weighted non-renal score, mean ± SD 2.3 (2.7) 3.5 (3.1) 1.7 (2.3) < 0.001
ACE and ARB prescription, n (%)  12,041 (23) 5,110 (29) 6,931 (20) < 0.001
 Alkali treatment, n (%) 807 (2) 461 (3) 346 (1) < 0.001
 Additional baseline labs, mean ± SD
 Serum albumin, g/dL 3.7 ± 0.6 3.5 ± 0.7 3.9 ± 0.5 < 0.001
 Serum calcium, corrected mg/dLa 9.3 ± 0.6 9.3 ± 0.7 9.4 ± 0.5 < 0.001
 Hemoglobin, g/dL 12.2 ± 2.0 11.3 ± 2.1 12.6 ± 1.8 < 0.001
 Serum potassium, mEq/L 4.4 ± 0.6 4.5 ± 0.7 4.4 ± 0.5 < 0.001
  1. Abbreviations: ACE Angiotensin-converting enzyme inhibitor, ACR Albumin-creatinine ratio, ARB Angiotensin II receptor blockers, CCI Charlson Comorbidity Index, CKD Chronic kidney disease, eGFR Estimated glomerular filtration rate, SD Standard deviationa Conversion factors for units, serum calcium mg/dL to mmol/L x 0.2495