Table 1.

Intraclass Correlation Coefficient (ICC) measured for kappa free light chain (KFLC) and albumin concentrations in cerebrospinal fluid (CSF) and serum and for K-Index = (CSF KFLC/Serum KFLC)/(CSF Albumin/serum Albumin); 95%CI: 95% confidence interval.

ICC	CSF KFLC (95%CI)	Serum KFLC (95%CI)	K-Index (95%CI)	CSF Albumin (95%CI)	Serum Albumin (95%CI)
Binding Site platform and assay (B) (nr = 4)	0.96 (0.9–0.98)	0.93 (0.63–0.98)	0.97 (0.94–0.99)	1.00 (0.99–1)	0.81 (0.41–0.94)
Siemens platform and assay (S) (nr = 3)	0.99 (0.97–100)	0.93 (0.48–0.98)	0.95 (0.89–0.98)	0.99 (0.98–1)	0.93 (0.8–0.98)
B + S (nr = 7)	0.93 (0.85–0.97)	0.91 (0.73–0.97)	0.91 (0.82–0.96)	0.98 (0.96–0.99)	0.83 (0.58–0.94)
All laboratories (nr = 8)	0.93 (0.87–0.97)	0.81 (0.53–0.93)	0.65 (0.43–0.84)	0.97 (0.96–0.99)	0.79 (0.55–0.92)