Table 1. Baseline Characteristics of Patients in the Chronic Kidney Disease Water Intake Trial (N = 631).
| Demographic and Clinical Characteristics | Treatment Group | |
|---|---|---|
| Hydration (n = 316) |
Control (n = 315) |
|
| Age, mean (SD), y | 64.8 (12.0) | 65.2 (11.6) |
| Men, No. (%) | 200 (63.3) | 200 (63.5) |
| Race/ethnicity, No. (%)a | ||
| White | 279 (88.3) | 293 (93.0) |
| South Asian | 14 (4.4) | 3 (1.0) |
| Black | 7 (2.2) | 8 (2.5) |
| Other | 16 (5.1) | 11 (3.5) |
| Weight, mean (SD), kg | 87.2 (18.9) | 87.2 (19.9) |
| BMI,b mean (SD) | 30.0 (6.0) | 29.8 (6.0) |
| Obese (BMI ≥30b), No. (%) | 149 (47.2) | 139 (44.1) |
| Current smoker, No. (%) | 30 (9.5) | 38 (12.1) |
| Daily fluid intake, mean (SD), L/d | 2.1 (0.8) | 2.0 (0.7) |
| Primary etiology of chronic kidney disease, No. (%) | ||
| Hypertension | 127 (40.2) | 119 (37.8) |
| Diabetes | 120 (38.0) | 105 (33.3) |
| Glomerulonephritis | 35 (11.1) | 41 (13.0) |
| Autoimmune | 15 (4.7) | 26 (8.3) |
| Polycystic kidney disease | 9 (2.9) | 9 (2.8) |
| Other/unknown | 10 (3.2) | 15 (4.8) |
| Chronic kidney disease stage, No. (%) | ||
| eGFRc ≥45 mL/min per 1.73 m2 | 141 (44.6) | 148 (47.0) |
| Urine albumin <30 mg/d | 28 (8.9) | 39 (12.4) |
| Urine albumin 30-300 mg/d | 58 (18.4) | 65 (20.6) |
| Urine albumin >300 mg/d | 49 (15.5) | 33 (10.5) |
| eGFRc<45 mL/min per 1.73 m2 | 175 (55.4) | 167 (53.0) |
| Urine albumin <30 mg/d | 31 (9.8) | 33 (10.5) |
| Urine albumin 30-300 mg/d | 77 (24.4) | 63 (20.0) |
| Urine albumin >300 mg/d | 53 (16.8) | 63 (20.0) |
| Comorbidities within last 10 y, No. (%) | ||
| Hypertension | 278 (88.3) | 278 (88.3) |
| Hyperlipidemia | 211 (67.2) | 206 (65.8) |
| Diabetes | 166 (52.7) | 137 (43.5) |
| Malignancy | 60 (19.1) | 72 (23.0) |
| Coronary artery disease | 64 (20.4) | 67 (21.3) |
| Cerebrovascular/transient ischemic attack | 36 (11.5) | 45 (14.3) |
| Peripheral vascular disease | 28 (8.9) | 28 (8.9) |
| Chronic obstructive pulmonary disease | 45 (14.2) | 43 (13.7) |
| Transplant | 13 (4.1) | 20 (6.3) |
| Congestive heart failure | 19 (6.0) | 11 (3.5) |
| Family history of hypertension or kidney failure, No. (%) | 181 (57.3) | 177 (56.2) |
| Systolic blood pressure, mean (SD), mm Hg | 140.8 (19.1) | 136.8 (17.2) |
| Diastolic blood pressure, mean (SD), mm Hg | 79.2 (10.3) | 77.7 (10.9) |
| Measures from blood samples, mean (SD) | ||
| eGFR (creatinine)c, mL/min per 1.73 m2 | 43.2 (10.2) | 43.7 (9.3) |
| eGFR (cystatin C)d, mL/min per 1.73 m2 | 46.7 (19.8) | 47.5 (19.3) |
| Copeptin, pmol/L | 16.6 (11.8) | 17.8 (13.7) |
| Cystatin C, mg/L | 1.6 (0.5) | 1.6 (0.4) |
| Sodium, mEq/L | 139.1 (2.7) | 139.2 (2.6) |
| Osmolality, mOsm/kg | 300.3 (7.4) | 301.2 (8.3) |
| Urea, mg/dL | 28.9 (9.5) | 28.6 (10.4) |
| Measures from 24-h urine samples | ||
| Urine volume, mean (SD), L/d | 1.9 (0.6) | 1.9 (0.6) |
| Creatinine, mean (SD), mmol/d | 11.9 (4.3) | 12.0 (3.7) |
| Osmolality, mean (SD), mOsm/kg | 447.4 (140.0) | 456.6 (132.9) |
| Urea, mean (SD), mmol/d | 339.6 (129.9) | 350.2 (125.7) |
| Sodium, mean (SD), mmol/d | 145.9 (62.4) | 149.2 (62.5) |
| Potassium, mean (SD), mmol/d | 63.3 (26.6) | 63.9 (23.4) |
| Albumin, median (IQR), mg/d | 108 (31-522) | 150 (40-507) |
| Creatinine clearance, mean (SD), mL/min per 1.73 m2 | 53.0 (18.7) | 54.0 (16.4) |
| Medications, No. (%) | ||
| ACE inhibitor or angiotensin receptor blocker | 217 (68.7) | 211 (67.0) |
| Statin | 203 (64.2) | 211 (67.0) |
| Calcium channel blockers | 134 (42.4) | 125 (39.7) |
| β-Blockers | 124 (39.2) | 127 (40.3) |
| Diuretic | 133 (42.1) | 113 (35.9) |
Abbreviations: ACE, angiotensin-converting enzyme; BMI, body mass index; CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; eGFR, estimated glomerular filtration rate; IQR, interquartile range.
SI conversion factors: To convert serum urea to mmol/L, multiply by 0.357.
a
Self-reported race/ethnicity was collected and recorded by a research assistant using prespecified categories; black/white racial origin is needed for the calculation of eGFR.
b
BMI was calculated as weight in kilograms divided by height in meters squared.
c
Calculated using the CKD-EPI creatinine equation.
d
Calculated using the CKD-EPI cystatin C equation.