AB1250 DIAGNOSTIC SIGNIFICANCE OF THE PROCALCITONIN TEST IN RHEUMATOLOGY
Authors: N. Muravyeva, B. Belov, G. Tarasova, M. Cherkasova
Journal: Annals of the Rheumatic Diseases (2020)

Background: Immuno-inflammatory rheumatic diseases (IIRDs) are often complicated by the infectious process, which may be due to both the disease itself and immunosuppressive therapy. At the same time, clinical symptoms and traditional laboratory tests are often uninformative in patients with active IIRDs, and negative results of bacteriological research do not exclude the presence of infection. One of the markers of bacterial inflammation – the procalcitonin test (PCT) - can play an important role in the early detection of infection in IIRDs. Objectives: The aim of the study is to assess the diagnostic significant of PCT in rheumatology. Methods: The study included 340 patients (227 women, 113 men, age 39.1±20.8 years) with different IIRDs: systemic lupus erythematosus (SLE) – 74, rheumatoid arthritis (RA) - 71, juvenile arthritis (JA) - 53, systemic vasculitis (SV) - 33, systemic scleroderma (SSD) - 27, ankylosing spondylitis (AS) - 18, adult-onset Still’s disease (AOSD) - 13, other IIRDs - 51. The serum concentration of PCT was determined by the quantitative electrochemiluminescent method using the Cobas E 411 analyzer (Roshe, Switzerland). Results: In patients without infection (n=181), the median (Me) PCT level was 0.11 ng/ml [0.05; 0.17]; higher values of PCT were found in patients with AOSD (0.39 ng/ml [0.14; 0.51]), systemic form of JA (0.17 ng/ml [0.11; 0.5]) and SLE (0.16 ng/ml [0.10-0.45]). In RA, SV, SSD, AS without infection, Me PCT was 0.07 ng/ml [0.03; 0.12]. The infectious process was detected in 159 patients: generalized - in 11, local - in 148. Depending on the severity of the intoxication syndrome, local infections are divided into severe (n=70) and light (n=78). Infections of the lower respiratory tract, urinary system, skin and soft tissues prevailed. In patients with generalized infection, Me PCT level was 3.6 ng/ml [0.49; 11.3]. In 10 patients of this group, the level of PCT exceeded 2 ng/ml, in 5 patients - 10 ng/ml. In severe local infection, Me PCT was 0.45 ng/ml [0.23; 1.19], in light - 0.12 ng/ml [0.05; 0.16]. In generalized infection, the level of PCT was significantly higher than in patients without infection (p&lt;0.0001), as well as with mild (p&lt;0.0001) and severe local infection (p&lt;0.0001). In patients with severe local infection, the level of PCT was higher compared to patients without infection (p&lt;0.0001) and with mild local infection (p&lt;0.001). There were no significant differences in PCT in the groups of patients with light local infection and without infection. In SLE patients with infection, the level of PCT and CRP (but not ESR) was higher than in patients without infection; a correlation was found between the level of PCT and CRP (r=0.53, p&lt;0.001) in the presence of infection. In AOSD, systemic form of JA, RA, SV, SSD, AS, significant differences in the levels of PCT, ESR, CRP in patients with infection and without infection were not obtained, correlations were not revealed. According to the ROC-analysis, the diagnostic significance of determining PCT in generalized infection is excellent, in severe local infection - very good, and in differentiation of generalized infection from local infection - very good. Conclusion: PCT is a significant diagnostic test that allows to recognize generalized and severe local infections in patients with IIRDs. In order to more accurately diagnose the infectious process, a multi-marker approach is needed. References: [1]Wu J-Y, Shen C-J, Hsieh Y-C, et al. Use of serum procalcitonin to direct bacterial infection in patients with autoimmune diseases: a systematic review and meta-analysis. Arthritis Rheum. 2012;64(9):3034-3042 doi: 10.1002/art.34512. Disclosure of Interests: None declared