Elevated systemic immune inflammation index level is associated with disease activity in ulcerative colitis patients

It has been confirmed that high Systemic immune-inflammation index (SII) levels usually indicate poor outcomes in various diseases, especially on malignancies. However, the clinical significance of the SII in ulcerative colitis (UC) patients is remain unclear. Therefore, the purpose of our paper is to analyze the levels of SII in UC patients and assess the relationship between the SII and disease activity. We studied 187 consecutive patients with UC and 185 age- and sex-matched healthy controls retrospectively. The Mayo scoring system was adopted to evaluate disease activity in UC patients. We collected clinical characteristics and laboratory parameters from hospital electronic medical records. The SII levels were significantly higher in UC patients than those in healthy subjects (P < 0.001). Higher SII levels were observed in moderate and severe UC subgroups compared to mild or remission subgroups. Correlation analysis displayed that the SII levels were positively relatived with Mayo score (r = 0.469, P < 0.001), C reactive protein (CRP) (r = 0.480, P < 0.001), and erythrocyte sedimentation rate (ESR) (r = 0.336, P < 0.001), but negatively with haemoglobin (Hb) (r = −0.271, P < 0.001). A multiple linear regression analysis suggested that there was an independent correlation between Mayo score and SII (beta = 0.324, t = 4.241, P < 0.001). The receiver operating characteristic (ROC) curve revealed that the maximum area under the curve (AUC) was 0.711 (95% CI, 0.630–0.791, P < 0.001), and the cut-off value for diagnosing active UC was 485.95, the sensitivity was 0.641, and the specificity was 0.75. We demonstrated that the SII was elevated significantly in UC patients and was closely related to the UC disease activity. In addition, the SII had a high discriminative capacity for active UC.