Table 4.
Prediction equations to estimate 24 h Na using correction applied for both spot Na and spot Cr using the INTERSALT equation (mmoL/day).
| Statistics | Measured 24 h Urinary Sodium Excretion | INTERSALT Spot 1 | INTERSALT Mean Day 1 and 2 | INTERSALT Adjusted Day 1 and 2 | INTERSALT Mean Day 1, 2, and 3 | INTERSALT Adjusted Day 1, 2, and 3 |
|---|---|---|---|---|---|---|
| Minimum | 32.00 | 4.48 | 12.06 | 11.00 | 14.21 | 12.27 |
| p5 | 49.00 | 21.09 | 39.03 | 42.41 | 48.53 | 45.41 |
| p10 | 56.00 | 90.52 | 102.67 | 105.63 | 109.21 | 106.67 |
| p25 | 66.00 | 132.82 | 119.21 | 122.35 | 120.76 | 122.20 |
| p50 | 107.00 | 140.74 | 132.96 | 141.44 | 133.02 | 141.39 |
| p75 | 154.00 | 167.67 | 164.70 | 164.97 | 172.34 | 165.93 |
| p90 | 201.00 | 212.32 | 209.14 | 208.46 | 198.68 | 204.26 |
| p95 | 220.00 | 215.77 | 209.20 | 213.71 | 207.71 | 206.18 |
| IQR | 88.00 | 34.85 | 45.48 | 42.62 | 51.57 | 43.74 |
| Maximum | 232.00 | 220.26 | 215.19 | 214.36 | 228.70 | 213.41 |
| Mean | 115.00 | 140.87 | 140.17 | 142.80 | 140.58 | 142.15 |
| SD | 56.33 | 51.30 | 49.01 | 48.10 | 47.86 | 47.01 |
| p-value * | 0.0208 | 0.0150 | 0.0150 | 0.0177 | 0.0163 | |
| Spearman r | 0.3083 | 0.2856 | 0.2727 | 0.2885 | 0.2579 | |
| p-value | 0.1524 | 0.1865 | 0.2080 | 0.1818 | 0.2348 |
* p-value of difference between measured 24 h urinary sodium excretion and each prediction equation using INTERSALT was assessed by Wilcoxon’s signed rank test. Na: sodium, Cr: creatinine.