POS1367 PROCALCITONIN IN RHEUMATOLOGY
Authors: K. Erraoui, K. Nassar, S. Janani
Journal: Annals of the Rheumatic Diseases (2021)

Background: The differentiation between infection and aseptic inflammation is difficult and often a challenge in the daily practice of rheumatology.Procalcitonin (PCT) is a preferred marker for bacterial infections that allows the rheumatologist to make an early diagnosis, choose an appropriate antibiotic therapy for bacterial infection, and avoid unnecessary antibiotic therapy for inflammation. Objectives: To study the levels of PCT in various inflammatory states observed in a rheumatology department, and to assess its possible discriminating role in the differentiation of bacterial infection from other inflammatory processes. Methods: This is a preliminary monocentric retrospective study conducted from January 2018 to December 2020 in our rheumatology department. The inclusion criteria were all patients hospitalized in rheumatology for a rheumatic or autoimmune disease or a bone and joint infection.PCT samples from patients were analyzed along with general signs (fever/chills) and with routine assessment (blood count including white blood cell count(WBC), erythrocyte sedimentation rate (ESR)and C reactive protein(CRP)) in patients admitted to hospitalfor a fever or a biological inflammatory syndrome, or both, with a laboratory cut-off value of 0.5 ng/ml. Results: 20 patients were included. Their mean age was 46.1 (extremes 19 – 66)and the with sex ratio was 1. Three patients had a history of autoimmune disease, 2 of neoplasia, 1 with chronic terminal kidney failure and hemodialysis, and 4 patients took antibiotics before hospitalization. The mean PCT was 100.01ng/ml (extremes 0.01-200), and Sensitivity at 57.44% and specificity at 100%, PPV: 100%, NPV: 81.25%. The patients were divided according to their final diagnosis into 3 groups: bacterial or fungal infection; inflammatory abacterian disease (autoimmune or rheumatic flare, neoplasia, metabolic, reactive arthritis); infection + inflammatory abacterian disease. Group 1 included 4 patients, their mean PCT was 6.92ng/ml (0.16-26.80),mean CRP was 131.725 mg/L, and mean ESR was 50 mm, and 25% had hyperleukocytosis.2 patients had already taken antibiotics before admission. Group 2 included 13 patients, their mean PCT was 0.025 ng/mL (0.01-0.13), mean CRP was 132.25mg/L, mean ESR was 84.38mm, and 30.77% of them had hyperleukocytosis. Group 3 included 3 patients, their mean PCT was 66.88 ng/mL (0.02-200), mean CRP was 560 mg/L, mean ESR was 107.33 mm, and 33.33% had hyperleucocytosis. The patient with the highest PCT was admitted for a sepsis with uremic encephalopathy that improved after hemodialysis. A control PCT was made in 2 patients with infection who received antibiotics,showing a decrease or negativation compared to the initial value of PCT. Conclusion: Our study showed that PCT levels only increased significantly in bacterial infections. The PCT values were more discriminating than the level of WBC and CRP in differentiating a bacterial infection from another inflammatory process, hence the value of using this marker in case diagnosis doubt. Group 1(n=4 ) Group 2(n=13 ) Group 3(n=3 ) Mean age 45 46.77 44.67 Sex ratio M/F 2/2 8/5 0/3 Reason for hospitalization Phlegmon of the left shoulder and inflammatory gonalgia in a feverish context 25% Multiple vertebral fractures 25% Acute monoarthritis of the left knee 25% Pain in the left hip with functional impairment 25% Inflammatory polyarthralgia15.38% Inflammatory back pain 23.07% Activity of his autoimmune 15.38% disease Chronic hip pain 7.69% Acute febrile polyarthralgia 30.77% Biarthritis 7.69% Acute febrile polyarthralgia 66.67% Flare of polymyalgia rheumatica 33.33% History Neoplasia 25% Autoimmune disease 23.07% End-stage chronic renal disease with hemodialysis 33.33% PCT indication Suspected septic arthritis 75% Exploration of inflammatory syndrome 25% Suspicion of arthritis 46.15% Exploration of inflammatory syndrome 53.85% Suspicion of sepsis 33.33% Exploration of inflammatory syndrome 66.67% Mean PCT value (ng/ml ) 6.92 0.025 66.88 fever/chills 75% 30.77% 33.33% Biological parameters Hyperleukocytosis ESR (mm ) CRP (mg/L ) 25% 50 131.725 30.77 % 84.38 132.25 33.33% 107.33 560 Disclosure of Interests: None declared