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Table 1 Baseline characteristics of insomnia patients by tertiles of serum sodium levels

From: Lower serum sodium levels predict poor clinical outcomes in patients with insomnia

Variables Total
(N = 412)
<  138.0 mg/dL
(N = 147)
138.0–140.9 mg/dL
(N = 136)
≥141.0 mg/dL
(N = 129)
P
Age (yr) 61.5 ± 14.8 63.4 ± 14.2 60.4 ± 16.1 60.4 ± 13.8 0.150
Men (%) 231 (56.1) 93 (63.3) 77 (56.6) 61 (47.3) 0.028
Body mass index (kg/m2) 23.5 ± 2.2 23.3 ± 2.0 23.6 ± 2.3 23.6 ± 2.2 0.431
Systolic blood pressure (mmHg) 124.2 ± 12.1 123.8 ± 11.9 124.7 ± 12.1 124.1 ± 12.5 0.826
Diastolic blood pressure (mmHg) 79.8 ± 7.8 79.9. ± 7.3 80.0 ± 8.0 79.5 ± 8.1 0.906
Serum sodium, (mmol/L) 138.9 ± 3.7 135.0 ± 2.9 139.6 ± 0.9 142.5 ± 1.6 <  0.001
Serum potassium (mmol/L) 4.1 ± 0.5 4.2 ± 0.5 4.2 ± 0.5 4.1 ± 0.5 0.570
Hemoglobin (g/dL) 12.6 ± 2.0 12.2 ± 1.9 12.8 ± 2.0 12.7 ± 2.0 0.012
Calcium (mg/dL) 8.9 ± 0.7 8.7 ± 0.6 9.0 ± 0.6 9.0 ± 0.6 <  0.001
Phosphorus (mg/dL) 3.5 ± 0.8 3.4 ± 0.9 3.6 ± 0.7 3.7 ± 0.7 0.025
Glucose (mg/dL) 129.9 ± 50.2 137.7 ± 59.6 130.9 ± 46.4 120.1 ± 40.1 0.015
Total Protein (g/dL) 6.5 ± 0.8 6.3 ± 0.8 6.6 ± 0.8 6.5 ± 0.7 0.043
Albumin (g/dL) 3.8 ± 0.7 3.5 ± 0.7 4.0 ± 0.7 4.0 ± 0.6 <  0.001
Cholesterol (mg/dL) 165.9 ± 45.2 159.6 ± 52.6 170.9 ± 41.7 171.5 ± 37.4 0.007
Uric acid (mg/dL) 4.6 ± 1.7 4.0 ± 1.9 4.8 ± 1.5 5.0 ± 1.6 <  0.001
eGFR (mL/min/1.73m2) 88.3 ± 24.8 89.0 ± 28.1 88.4 ± 22.4 87.4 ± 22.4 0.787
Follow up duration (month) 49.4 ± 29.0 42.5 ± 29.2 53.8 ± 27.7 52.9 ± 28.9 0.001
Charlson Comorbidity Index (CCI) Score      < 0.001
CCI score 0–2 (%) 161 (39.1) 36 (24.5) 61 (44.9) 64 (49.6)  
CCI score 3–4 (%) 145 (35.2) 56 (38.1) 47 (34.6) 42 (32.6)  
CCI score ≥ 5 (%) 106 (25.7) 55 (37.4) 28 (20.6) 23 (17.8)  
Use of thiazide (%) 32 (7.8) 12 (8.2) 11 (8.1) 9 (7.0) 0.920
  1. eGFR estimated glomerular filtration rate