Table 3.

Rank correlation coefficients and the 95% limits of agreement between measurements of six inflammatory markers in induced and spontaneous sputum samples

	Correlation coefficient *	Bland & Altmans 95% limit of agreement †
		Lower	Upper
IL-6 (pg/ml)	0.729	0.12	6.35
IL-8 (pg/ml)	0.695	0.12	5.59
IP-10 (pg/ml)	0.833	0.08	13.7
TNFα (pg/ml)	0.600	0.11	5.53
IL-18 (pg/ml)	0.583	0.09	29.99
MIG (pg/ml)	0.754	0.10	17.24

^*Spearman’s rank correlation test.

^†±2 SD of the mean difference between the two measurements.