INFLA-score: a new diagnostic paradigm to identify pericarditis

Diagnosis of pericarditis may be challenging, since not all patients meet conventional criteria. An overlooked diagnosis implies longer course of symptoms and increased risk of recurrences. C-reactive protein(CRP), widely used as inflammation marker, has some limitations. This study aimed to assess usefulness and prognostic value of INFLA-score, a validated index assessing low-grade inflammation, in the definite diagnosis of pericarditis.Patients with suspected pericarditis were included. INFLA-score was computed based on white blood cells and platelet count, neutrophil-to-lymphocyte ratio, CRP, ranging from -16 to+16. INFLA-score>0 was considered positive for the presence of pericardial inflammation. The primary end-point was the association of INFLA-score with diagnosis of pericarditis according to conventional criteria. Recurrence of pericarditis at 6 months was secondary end-point.202 patients were included, aged 47±17,57% females. Among 72(36%) patients with diagnosis of pericarditis, INFLA-score>0 was observed in 86%(vs.36%,p<0.001), abnormal CRP in 42%(vs.10%,p<0.001), pericardial effusion in 44%(vs.19%,p<0.001), abnormal ECG in 56%(vs.24%,p<0.001), rubs in 5%(vs.0.1%,p=0.072). INFLA-score>0 had strongest predictive value for the diagnosis of pericarditis (HR 8.48, 95%CI 3.39-21.21), with 86%sensitivity and 64%specificity, opposed to CRP (HR 1.72, non-significant 95%CI 3.39-21.20). Recurrent pericarditis at 6-month was more frequent in patients with positive INFLA-score (37% vs.8%,p<0.001, RR 4.15,95%CI 2.81-6.12). Among patients with normal CRP, INFLA-score confirmed ongoing inflammation in 78%cases. Compared with conventional criteria, INFLA-score had highest accuracy(AUC=0.82). Different cut-offs were valuable to rule-out(INFLA-score>0,sensitivity86%,negativeLR=0.22) or rule-in(INFLA-score≥10,specificity97%, positiveLR=13) diagnosis.INFLA-score is a useful diagnostic tool to assess the probability of pericarditis, with a strong prognostic value for further recurrences, outperforming CRP.