In group lb (chronic group; n = 31), the RUCs for sIL2R (P = 0.
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.
The reason for its poorer performance compared with sIL2R might, at least in part, may be explained by the fact that ACE concentrations can be influenced by an ACE polymorphism (I/D polymorphism in intron 16 of the ACE gene) (29, 30).
These results are in agreement with a previous study, which found that the mean CRP concentrations in patients with stable or progressing disease (indicating severe disease) did not differ significantly from those in controls, in contrast to sIL2R (16).
Similar results were demonstrated for sIL2R, CRP, and SAA in the present study.
In the untreated group of patients, sIL2R appeared to be the best marker for predicting disease severity, whereas the traditionally used ACE appeared comparable to hs-CRP and SAA.
Serum sIL2R measurement in sarcoidosis patients: a clinical evaluation.
5] Nonstandard abbreviations: IL, interleukin; hs-CRP, high-sensitivity Creactive protein; SAA, serum amyloid A; sIL2R, soluble interleukin-2-receptor; ACE, angiotensin-converting enzyme; RFI, respiratory functional impairment; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; DLCO, diffusing capacity for carbon monoxide; and AUC, area under the curve.