Table 3.
Agreement between total calcium and free calcium as measured by Harrell’s c Index (95% CI) in patients with estimated glomerular filtration rate (eGFR) above or below normal 60 mL/min/1.73 m2
| Adjustment formula | eGFR≥60 mL/min/1.73 m2 (n=5013) | eGFR<60 mL/min/1.73 m2 (n=1536) |
| None | 0.749 (0.741–0.758) | 0.801 (0.788–0.813) |
| Local* | 0.749 (0.741–0.758) | 0.790 (0.776–0.803) |
| James et al20 | 0.751 (0.743–0.759) | 0.791 (0.777–0.804) |
| Orrell4 | 0.736 (0.728–0.745) | 0.766 (0.751–0.781) |
| BMJ6 | 0.728 (0.719–0.737) | 0.753 (0.738–0.769) |
| Thode 19 | 0.726 (0.717–0.735) | 0.747 (0.731–0.763) |
| Berry et al7 | 0.716 (0.707–0.725) | 0.736 (0.720–0.752) |
| Payne et al5 | 0.707 (0.698–0.716) | 0.723 (0.707–0.740) |
*The local adjustment formulas were constructed using three subgroup-specific albumin coefficients; see Material and methods.