Table 1.
Baseline Characteristics of Patients With Normal Admission Sodium and Patients With Either Hyponatremia or Hypernatremia on Admission
| Hyponatremia (n=1706) | Normal Sodium (n=7648) | Hypernatremia (n=322) | P Value | |
|---|---|---|---|---|
| Baseline demographics | ||||
| Age, y | 66.9±15.4 | 67.5±15.1 | 70.7±14.3 | <0.001 |
| Female sex | 698 (40.9%) | 2804 (36.7%) | 125 (38.8%) | 0.004 |
| White race | 1551 (90.9%) | 7095 (92.8%) | 290 (90.1%) | 0.010 |
| BMI | 29.7±7.5 | 29.5±6.9 | 29.0±7.5 | 0.23 |
| Comorbidities | ||||
| Charlson comorbidity index | 2.8±2.7 | 2.3±2.6 | 2.8±2.7 | <0.001 |
| Previous MI | 347 (20.4%) | 1522 (20.0%) | 58 (18.1%) | 0.63 |
| Previous HF | 450 (26.4%) | 1385 (18.2%) | 73 (22.7%) | <0.001 |
| Previous DM | 596 (35.0%) | 2073 (27.2%) | 93 (29.0%) | <0.001 |
| Previous stroke | 203 (11.9%) | 935 (12.2%) | 51 (15.9%) | 0.13 |
| Previous liver disease | 70 (4.1%) | 115 (1.5%) | 5 (1.6%) | <0.001 |
| Previous cancer | 419 (24.6%) | 1557 (20.4%) | 87 (27.1%) | <0.001 |
| Previous lung disease | 369 (21.7%) | 1437 (18.8%) | 75 (23.4%) | <0.001 |
| Previous CKD | 419 (24.6%) | 1472 (19.3%) | 90 (28.0%) | <0.001 |
| Previous dialysis | 163 (9.6%) | 383 (5.0%) | 17 (5.3%) | <0.001 |
| Severity of illness | ||||
| APACHE‐III | 69.6±26.0 | 59.5±24.2 | 72.8±32.8 | <0.001 |
| APACHE‐IV | 0.228±0.224 | 0.156±0.190 | 0.260±0.264 | <0.001 |
| Day 1 SOFA | 4.7±3.6 | 3.3±3.0 | 5.2±4.0 | <0.001 |
| Maximum week 1 SOFA | 5.2±3.8 | 3.6±3.1 | 5.4±4.0 | <0.001 |
| Mean week 1 SOFA | 3.9±3.1 | 2.8±2.5 | 4.4±3.6 | <0.001 |
| Procedures and therapies | ||||
| Invasive ventilator | 350 (20.5%) | 1138 (14.9%) | 101 (31.4%) | <0.001 |
| Noninvasive ventilator | 315 (18.5%) | 1086 (14.2%) | 76 (23.6%) | <0.001 |
| Vasoactive drugs | 675 (39.6%) | 1655 (21.6%) | 96 (29.8%) | <0.001 |
| Vasopressors | 576 (33.8%) | 1389 (18.2%) | 86 (26.7%) | <0.001 |
| Inotropes | 287 (16.8%) | 600 (7.8%) | 28 (8.7%) | <0.001 |
| Dialysis | 174 (10.2%) | 286 (3.7%) | 18 (5.6%) | <0.001 |
| CRRT | 83 (4.9%) | 83 (1.1%) | 1 (0.3%) | <0.001 |
| IABP | 201 (11.8%) | 622 (8.1%) | 28 (8.7%) | <0.001 |
| PAC | 208 (12.2%) | 490 (6.4%) | 22 (6.8%) | <0.001 |
| RBC transfusion | 294 (17.2%) | 824 (10.8%) | 52 (16.2%) | <0.001 |
| Coronary angiography | 832 (48.8%) | 4130 (54.0%) | 131 (40.7%) | <0.001 |
| PCI | 459 (26.9%) | 2824 (36.9%) | 58 (18.0%) | <0.001 |
| Admission vital signs | ||||
| Systolic BP | 117.3±27.4 | 124.2±25.7 | 123.5±28.9 | <0.001 |
| Diastolic BP | 66.7±17.7 | 70.0±16.7 | 68.9±18.6 | <0.001 |
| Mean BP | 80.0±19.3 | 84.2±17.6 | 83.8±19.4 | <0.001 |
| Heart rate | 86.2±22.7 | 81.1±23.4 | 84.7±24.8 | <0.001 |
| Shock index | 0.77±0.28 | 0.68±0.26 | 0.73±0.29 | <0.001 |
| Respiratory rate | 19.4±5.7 | 18.2±5.7 | 19.3±6.9 | <0.001 |
| Oxygen saturation | 95.2±6.7 | 95.9±5.6 | 94.0±9.4 | <0.001 |
| Admission laboratory data | ||||
| Serum sodium | 130.9±3.8 | 139.0±2.4 | 146.8±2.6 | <0.001 |
| Serum potassium | 4.4±0.8 | 4.2±0.6 | 4.1±0.7 | <0.001 |
| Serum bicarbonate | 23.2±4.7 | 24.0±4.2 | 23.5±6.0 | <0.001 |
| Serum chloride | 96.8±5.8 | 103.9±4.3 | 109.0±5.2 | <0.001 |
| Serum anion gap | 12.3±4.0 | 11.5±3.4 | 13.3±4.7 | <0.001 |
| Serum magnesium | 2.1±0.4 | 2.0±0.3 | 2.1±0.05 | 0.001 |
| BUN | 34.4±25.6 | 24.7±16.2 | 32.1±21.2 | <0.001 |
| Serum creatinine | 1.7±1.5 | 1.3±1.0 | 1.4±1.0 | <0.001 |
| Serum glucose | 168.0±93.6 | 146.6±65.7 | 154.4±71.3 | <0.001 |
| Discharge ICD‐9 diagnoses | ||||
| Shock | 302 (17.7%) | 685 (9.0%) | 58 (18.0%) | <0.001 |
| Cardiomyopathy | 342 (20.1%) | 956 (12.5%) | 47 (14.6%) | <0.001 |
| HF | 914 (53.6%) | 2721 (35.6%) | 156 (48.4%) | <0.001 |
| AF | 665 (39.0%) | 2289 (30.0%) | 139 (43.2%) | <0.001 |
| Cardiac arrest | 164 (9.6%) | 575 (7.5%) | 46 (14.3%) | <0.001 |
| ACS | 622 (36.5%) | 3417 (44.7%) | 107 (33.2%) | <0.001 |
| Sepsis | 182 (10.7%) | 435 (5.7%) | 32 (9.9%) | <0.001 |
| Respiratory failure | 445 (26.1%) | 16.8%) | 117 (36.3%) | <0.001 |
| Outcomes | ||||
| CICU LOS | 3.4±6.4 | 2.4±4.2 | 2.5±2.8 | <0.001 |
| Hospital LOS | 11.4±15.8 | 7.3±12.6 | 8.9±13.8 | <0.001 |
| CICU mortality | 154 (9.0%) | 345 (4.5%) | 41 (12.7%) | <0.001 |
| Hospital mortality | 265 (15.5%) | 542 (7.1%) | 57 (17.7%) | <0.001 |
Data reported as frequency (percent) or mean±SD. Reported P values are for chi‐squared test (categorical variables) or ANOVA (continuous variables) across groups. ACS indicates acute coronary syndrome; AF, atrial fibrillation; APACHE, Acute Physiology and Chronic Health Evaluation; BMI, body mass index; BP, blood pressure; BUN, blood urea nitrogen; CICU, cardiac intensive care unit; CKD, chronic kidney disease; CRRT, continuous renal‐replacement; DM, diabetes mellitus; HF, heart failure; IABP, intra‐aortic balloon pump; LOS, length of stay; MI, myocardial infarction; PAC, pulmonary artery catheterization; PCI, percutaneous intervention; RBC, red blood cell; SOFA, Sequential Organ Failure Assessment.