Table 1.
Baseline characteristics among incident peritoneal dialysis patients according to baseline sodium level
| Serum sodium level (mEq/L) |
P* | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Overall | <134 | 134 to <136 | 136 to <138 | 138 to <140 | 140 to <142 | 142 to <144 | ≥144 | ||
| N | 4687 | 148 | 251 | 654 | 1368 | 1424 | 672 | 170 | N/A |
| Age, years (±SD) | 58 ± 15 | 59 ± 14 | 58 ± 16 | 56 ± 15 | 56 ± 16 | 58 ± 15 | 60 ± 15 | 59 ± 16 | <0.001 |
| Female (%) | 45 | 61 | 47 | 48 | 46 | 44 | 40 | 32 | <0.001 |
| Race/ethnicity (%) | |||||||||
| Caucasian | 60 | 67 | 58 | 58 | 58 | 61 | 64 | 63 | 0.16 |
| African-American | 20 | 10 | 20 | 18 | 21 | 21 | 20 | 24 | 0.009 |
| Asian | 5 | 5 | 4 | 6 | 5 | 4 | 4 | 1 | 0.04 |
| Hispanic | 11 | 14 | 14 | 15 | 12 | 10 | 9 | 7 | <0.001 |
| Other | 4 | 4 | 4 | 3 | 4 | 4 | 3 | 5 | 0.58 |
| Primary insurance (%) | |||||||||
| Medicare | 44 | 51 | 44 | 46 | 44 | 45 | 44 | 42 | 0.20 |
| Medicaid | 4 | 5 | 6 | 5 | 4 | 4 | 2 | 4 | 0.03 |
| Other | 52 | 45 | 50 | 50 | 53 | 51 | 54 | 54 | <0.001 |
| Comorbidities (%) | |||||||||
| Diabetes | 58 | 67 | 69 | 71 | 60 | 53 | 52 | 48 | <0.001 |
| Hypertension | 48 | 39 | 49 | 48 | 45 | 49 | 51 | 50 | 0.06 |
| Atherosclerotic heart disease | 13 | 12 | 14 | 13 | 13 | 12 | 14 | 13 | 0.98 |
| Other cardiovascular disease | 9 | 7 | 10 | 12 | 9 | 9 | 10 | 7 | 0.37 |
| Congestive heart failure | 6 | 5 | 9 | 8 | 5 | 5 | 6 | 4 | 0.03 |
| Cerebrovascular disease | <1 | <1 | 1 | <1 | 1 | 0 | <1 | <1 | 0.48 |
| Thyroid disorders | 15 | 18 | 17 | 16 | 14 | 14 | 16 | 12 | 0.41 |
| COPD | 2 | 1 | 3 | 3 | 1 | 2 | 2 | 3 | 0.77 |
| Malignancy | 1 | <1 | <1 | 1 | 1 | 2 | 1 | 1 | 0.92 |
| HIV | <1 | 0 | 0 | <1 | 0 | 0 | 0 | 0 | 0.76 |
| Alcohol | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0.07 |
| Liver disease | <1 | <1 | 1 | <1 | 1 | 0 | <1 | 0 | 0.09 |
| Use of APD (%) | |||||||||
| At study entry | 45 | 35 | 37 | 42 | 45 | 46 | 47 | 51 | <0.001 |
| Any time during study follow-up | 83 | 80 | 76 | 81 | 85 | 84 | 85 | 87 | 0.001 |
| Laboratory tests [mean ± SD or median (IQR)] | |||||||||
| 4-h PET D/P creatinine | 0.64 ± 0.12 | 0.64 ± 0.12 | 0.65 ± 0.12 | 0.65 ± 0.12 | 0.63 ± 0.12 | 0.64 ± 0.12 | 0.64 ± 0.12 | 0.64 ± 0.13 | 0.18 |
| 4-h PET ultrafiltration volume (mL) | 300 (100, 400) | 400 (200, 500) | 300 (175, 400) | 300 (100, 450) | 300 (200, 450) | 300 (100, 400) | 275 (100, 400) | 225 (0, 400) | <0.001 |
| Renal urea clearance (renal Kt/V) | 1.2 ± 0.8 | 1.0 ± 0.7 | 1.0 ± 0.8 | 1.1 ± 0.8 | 1.3 ± 0.8 | 1.3 ± 0.8 | 1.3 ± 0.8 | 1.3 ± 0.8 | <0.001 |
| Peritoneal clearance (peritoneal Kt/V) | 1.4 ± 0.4 | 1.6 ± 0.5 | 1.5 ± 0.4 | 1.5 ± 0.5 | 1.4 ± 0.4 | 1.4 ± 0.4 | 1.4 ± 0.4 | 1.4 ± 0.4 | <0.001 |
| Serum albumin (g/dL) | 3.7 ± 0.5 | 3.4 ± 0.5 | 3.5 ± 0.6 | 3.6 ± 0.5 | 3.7 ± 0.5 | 3.8 ± 0.4 | 3.7 ± 0.4 | 3.7 ± 0.5 | <0.001 |
| Serum creatinine (mg/dL) | 5.9 ± 2.4 | 5.4 ± 2.3 | 5.7 ± 2.4 | 6.0 ± 2.6 | 5.9 ± 2.4 | 5.9 ± 2.4 | 5.8 ± 2.4 | 5.8 ± 2.4 | 0.86 |
| Serum potassium (mEq/L) | 4.2 ± 0.5 | 4.2 ± 0.5 | 4.2 ± 0.5 | 4.2 ± 0.5 | 4.2 ± 0.5 | 4.2 ± 0.5 | 4.1 ± 0.5 | 4.1 ± 0.6 | <0.001 |
| Glucose (mg/dL) | 158 ± 67 | 207 ± 144 | 200 ± 89 | 185 ± 79 | 160 ± 63 | 143 ± 51 | 133 ± 40 | 124 ± 36 | <0.001 |
| TIBC (mg/dL) | 257 ± 47 | 248 ± 25 | 249 ± 54 | 256 ± 47 | 260 ± 48 | 259 ± 45 | 256 ± 45 | 255 ± 43 | 0.05 |
| Bicarbonate (mEq/L) | 25 ± 3 | 25 ± 3 | 25 ± 3 | 24 ± 3 | 24 ± 3 | 25 ± 3 | 25 ± 3 | 26 ± 3 | <0.001 |
| Calcium (mg/dL) | 9.1 ± 0.7 | 9.2 ± 0.5 | 9.2 ± 0.8 | 9.2 ± 0.6 | 9.1 ± 0.7 | 9.1 ± 0.7 | 9.1 ± 0.7 | 9.2 ± 0.7 | <0.001 |
| Phosphorus (mg/dL) | 4.7 ± 1.1 | 4.8 ± 1.1 | 4.7 ± 1.0 | 4.9 ± 1.2 | 4.8 ± 1.0 | 4.7 ± 1.0 | 4.6 ± 1.1 | 4.7 ± 1.2 | <0.001 |
| Intact PTH (pg/mL) | 266 (159, 429) | 206 (127, 368) | 238 (144, 400) | 249 (154, 420) | 268 (159, 426) | 281 (166, 445) | 271 (167, 458) | 246 (147, 379) | 0.03 |
| Ferritin (ng/mL) | 199 (110, 348) | 222 (124, 348) | 241 (122, 478) | 209 (106, 375) | 200 (108, 335) | 192 (107, 340) | 200 (115, 344) | 180 (94, 319) | 0.006 |
| Iron saturation (%) | 26 ± 9 | 26 ± 10 | 28 ± 10 | 27 ± 11 | 26 ± 9 | 26 ± 9 | 26 ± 9 | 26 ± 10 | 0.25 |
| Hemoglobin (g/dL) | 11.4 ± 1.3 | 11.3 ± 1.4 | 11.4 ± 1.2 | 11.3 ± 1.3 | 11.4 ± 1.3 | 11.4 ± 1.3 | 11.5 ± 1.3 | 11.4 ± 1.4 | 0.06 |
| WBC (×103/µL) | 7.4 ± 2.4 | 7.9 ± 3.4 | 7.6 ± 2.4 | 7.4 ± 2.3 | 7.4 ± 2.5 | 7.4 ± 2.3 | 7.2 ± 2.0 | 7.2 ± 2.3 | 0.007 |
*P-for-trend values.
COPD, chronic obstructive pulmonary disease; HIV, human immunodeficiency virus; PET, peritoneal equilibrium test; D/P, dialysate to plasma; APD, automated peritoneal dialysis; TIBC, total iron binding capacity; PTH, parathyroid hormone; WBC, white blood cell count.