Predictive Value of the Systemic Immune-inflammation Index for Recurrence of Idiopathic Acute Pericarditis

Abstract Background Identifying patients at increased risk of recurrence of acute pericarditis remains challenging. High-sensitivity C-reactive protein (hs-CRP) can be used to predict recurrence, but it has certain limitations. Objectives This study aimed to evaluate the association between a novel biomarker, the Systemic Immune-Inflammation Index (SII), and the recurrence of acute pericarditis. Methods This retrospective cohort study included 110 patients diagnosed with acute idiopathic pericarditis, the primary endpoint of the study was to investigate Recurrent Pericarditis (RP) during the 18 month follow-up period. Patients were divided into two groups based on whether or not they developed recurrent pericarditis. Physical examination, electrocardiography, echocardiography, and laboratory test results of these patients were evaluated. P < 0.05 was considered statistically significant. Results The mean age of the patients was 42.8 ± 15.2 years, and 42.7% were male. The group with RP had significantly higher leukocyte counts (8.7 ± 3.2 vs. 12 ± 4.7; p = 0.001), neutrophil counts (5.4 ± 2.7 vs. 9 ± 4.5; p < 0.001), hs-CRP levels (29.1 ± 40.9 vs. 49.5 ± 62.2; p = 0.048), and neutrophil-to-lymphocyte ratio (2.9 ± 2.5 vs. 6 ± 2.8; p < 0.001). SII (783.2 ± 770.2 vs. 1664.2 ± 1086.6; p < 0.001) was also significantly higher in patients with recurrence. Both SII and hs-CRP were independently associated with recurrence (p < 0.001 and p < 0.05, respectively). Conclusion SII and hs-CRP were found to be independent predictors for recurrence in acute pericarditis patients during the 18 month follow-up. Similar to hs-CRP, SII may also be used as an important parameter in predicting recurrent pericarditis.