INFLA-score: a new diagnostic paradigm to identify pericarditis.

BACKGROUND: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: INFLA-score is a useful diagnostic tool to assess the probability of pericarditis, with a strong prognostic value for further recurrences, outperforming CRP.