Clinical significance of non-infectious procalcitonin elevation in Still’s disease: A predictor of macrophage activation syndrome

Abstract Objectives Still’s disease (SD) is an autoinflammatory disease (AID) that can lead to life-threatening macrophage activation syndrome (MAS). The role of procalcitonin (PCT) in AIDs remains unclear. This study aims to explore the relationship between non-infectious PCT elevation and clinical features of SD. Methods This retrospective study included patients with SD and absence of infection who had available PCT data. Control groups consisted of patients with confirmed bloodstream infections and age- and sex-matched healthy controls (HCs). A PCT cut-off of 0.5 ng/ml was used. Clinical and laboratory findings were evaluated based on baseline (PCT < 0.5 and PCT ≥ 0.5 groups) and maximum (PCTmax<0.5 and PCTmax≥0.5 groups) values. Results The study conducted with 110 patients with SD. Of these, 75 (68%) were in the PCT < 0.5 group and 35 (32%) were in the PCT ≥ 0.5 group, while 63 (57.3%) were in the PCTmax<0.5 group and 47 (42.7%) were in the PCTmax≥0.5 group. PCT levels were significantly higher in patients with SD compared with HCs and were nearly as elevated in MAS cases as in infection. Frequency of MAS, higher mPouchot scores and increased use of biologic DMARDs, particularly anakinra, were associated with elevated PCT. MAS risk increased 6.4-fold in the PCT ≥ 0.5 group and 7.6-fold in the PCTmax≥0.5 group in univariate analysis, and 4.3-fold and 5.4-fold, respectively, in multivariate analysis. Conclusion PCT may be a potential marker in AIDs such as SD, even in the absence of infection. Elevated PCT levels may serve as an independent predictor of MAS in SD.