Table 1.
Demographics and clinical characteristics of the study cohort
| Total study cohort (n = 51 558) | Metabolic acidosis (n = 17 350) | Normal serum bicarbonate (n = 34 208) | P-value | |
|---|---|---|---|---|
| Sex, n (%) | ||||
| Male | 24 464 (47) | 8339 (48) | 16 125 (47) | 0.05 |
| Age, mean (SD) (years) | 72.9 (11.5) | 70.3 (13.3) | 74.3 (10.3) | <0.001 |
| Race, n (%) | ||||
| African American | 5128 (10) | 2585 (15) | 2543 (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 | 3379 (7) | 1501 (9) | 1878 (5) | <0.001 |
| US region, n (%) | ||||
| Midwest | 30 683 (60) | 9359 (54) | 21 324 (62) | <0.001 |
| Northeast | 2603 (5) | 1175 (7) | 1428 (4) | <0.001 |
| Other/Unknown | 586 (1) | 227 (1) | 359 (1) | 0.01 |
| South | 14 107 (27) | 5329 (31) | 8778 (26) | <0.001 |
| West | 3579 (7) | 1260 (7) | 2319 (7) | 0.04 |
| Baseline serum bicarbonate (mmol/L), mean (SD) | 24.0 (3.6) | 19.7 (1.1) | 26.1 (2.0) | <0.001 |
| Baseline eGFR (mL/min/1.73 m2), mean (SD) | 41.2 (12.1) | 37.2 (13.3) | 43.2 (10.9) | <0.001 |
| CKD stage, n (%) | ||||
| Stage 3a | 22 431 (44) | 5719 (33) | 16 712 (49) | <0.001 |
| Stage 3b | 19 081 (37) | 5987 (35) | 13 094 (38) | <0.001 |
| Stage 4 | 8736 (17) | 4747 (27) | 3989 (12) | <0.001 |
| Stage 5, nondialysis | 1310 (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) | 7391 (43) | 8777 (26) | <0.001 |
| CAD | 14 329 (28) | 6249 (36) | 8080 (24) | <0.001 |
| PVD | 10 052 (19) | 5038 (29) | 5014 (15) | <0.001 |
| Heart failure | 10 029 (19) | 5119 (30) | 4910 (14) | <0.001 |
| Protein-calorie malnutrition | 895 (2) | 640 (4) | 255 (1) | <0.001 |
| CCI, mean (SD) | 2.3 (2.7) | 3.5 (3.1) | 1.7 (2.3) | <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/dL) | 9.3 (0.6) | 9.3 (0.7) | 9.4 (0.5) | <0.001 |
| Hemoglobin (g/dL) | 12.2 (2) | 11.3 (2.1) | 12.6 (1.8) | <0.001 |
| Serum potassium (mmol/L) | 4.4 (0.6) | 4.5 (0.7) | 4.4 (0.5) | <0.001 |
| Fall during pre-index year, n (%) | 1147 (2) | 675 (4) | 472 (1) | <0.001 |
| Fracture during pre-index year, n (%) | 802 (2) | 445 (3) | 357 (1) | <0.001 |
| Alkali treatment prescription, n (%) | 502 (1) | 329 (2) | 173 (1) | <0.001 |
The reference race was Caucasian. Conversion factor for units: serum calcium in mg/dL to µmol/L, × 0.2495.
Fall or fracture was evaluated for 1 year preceding the index date.
Due to missing data, prescriptions were calculated as a percentage of patients with at least one prescription of any kind during the pre-index year (N = 13 924 in the metabolic acidosis group and N = 21 314 in the normal serum bicarbonate group).
Data on patients contributing laboratory data is provided in Supplementary data, Table S3.
Distribution of baseline serum bicarbonate is provided in Supplementary data, Table S5.
Abbreviations: CCI, Charlson Comorbidity Index; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; SD, standard deviation.