The distributions of the explanatory variables CRP, SAA, ACE, and sIL2R were positively skewed; therefore, the data are presented as medians and interquartile ranges.
Treated patients appeared to have significantly lower sIL2R concentrations compared with the untreated patients (P <0.05).
In the group of untreated patients (group I; n = 73), the AUC for sIL2R was significantly larger than the AUC for ACE (P = 0.033), but we found no significant difference for sIL2R compared with hs-CRP (P = 0.236) or SAA (P = 0.180).
However, in all three tested groups, the AUC for sIL2R was the largest.
The combinations of sIL2R and hs-CRP, sIL2R and SAA, and sIL2R and ACE yielded AUCs (SE) of 0.812 (0.054), 0.803 (0.056), and 0.803 (0.057), respectively, for group I and 0.733 (0.059), 0.732 (0.059), and 0.708 (0.061) for group II.
In group la (nonchronic group; n = 42), only sIL2R (P <0.0001) and ACE (P <0.04) had an AUC significantly different from the null hypothesis; the P values for the RUCs for hs-CRP and SAA were 0.141 and 0.074, respectively.
In group lb (chronic group; n = 31), the RUCs for sIL2R (P = 0.043), hs-CRP (P = 0.019), and SAA (P = 0.035) all were significantly different from the AUC of 0.5 (P <0.05), in contrast to ACE (P = 0.536).
The combinations of sIL2R and hs-CRP, sIL2R and SAA, and sIL2R and ACE yielded AUCs (SE) of 0.812 (0.067), 0.889 (0.055), and 0.880 (0.058), respectively, for group la and 0.777 (0.083), 0.723 (0.093), and 0.723 (0.043) for group lb.
Somewhat overlapping sensitivity and specificity confidence intervals were observed, but sIL2R had the highest combination of positive and negative predictive values among the markers: 70% and 85%, respectively, for group 1; 82% and 94% for group la; and 67% and 84% for group lb.
Although determining the prognostic value of sIL2R in untreated patients was beyond the scope of this study and should be addressed in a prospective study, some follow-up data were available.
In the whole untreated sarcoidosis patient group as well as in the subgroups of untreated group divided according to the time since diagnosis (group Ia, the nonchronic group, and group lb, the chronic group), ROC curves and logistic regression analysis indicated that sIL2R has the highest ability to determine pulmonary severity.
Although the sensitivity confidence intervals for ACE and sIL2R were largely overlapping, the positive predictive values were higher for sIL2R than for ACE.