Table 3.

Agreement between iCa concentration and the other estimators of blood calcium concentration^a

iCa	Noncorrected tCa	Albumin-Corrected Ca, Formula 1	Albumin-Corrected Ca, Formula 2
Overall (n = 691)
agreement	545	547	549
underestimation	76	69	58
overestimation	70	75	84
κ coefficient (95% CI)	0.29 (0.20 to 0.38)	0.28 (0.19 to 0.37)	0.25 (0.16 to 0.34)
Low (n = 109)
agreement	44	39	32
sensitivity/specificity (%)	40.4/90.7	35.8/91.2	29.4/93.8
High (n = 28)
agreement	6	6	6
sensitivity/specificity (%)	21.4/99.2	21.4/99.2	21.4/98.8
Normal (n = 554)
agreement	495	502	511
overestimation	5	5	7
underestimation	54	47	36

^aCI, confidence interval.