Systemic Immune Inflammation Index as a Reliable Disease Activity Marker in Psoriatic Arthritis

To assess the utility of systemic immune inflammation index (SII) in predicting disease activity in psoriatic arthritis (PsA) patients.A descriptive study.Dışkapı Yıldırım Beyazıt Research and Training Hospital, Ankara, Turkey, from October 2020 to September 2021.This study included 106 PsA and 103 age and gender-matched healthy individuals. Neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), monocyte to lymphocyte ratio (MLR), and SII were calculated from complete blood count parameters. The PsA disease activity was assessed by using disease activity score-ESR and DAS-CRP based on 28 joints and the Disease Activity in Psoriatic Arthritis (DAPSA) scores. The receiver operating characteristic (ROC) curve was performed to evaluate the utility of SII in determining disease activity in PsA patients.The NLR, PLR, MLR, and SII were significantly higher in PsA patients compared to healthy control (p=0.013, p=0.019, p=0.012, and p=0.002, respectively). There were statistically significant positive correlations between the DAS28-ESR, DAS28-CRP, and DAPSA and SII (p<0.001, p<0.001, and p<0.001 respectively). The SII values were significantly higher in PsA patients with moderate to severe disease activity according to DAPSA scores when compared to patients with remission or low disease activity (p<0.001). The cut-off value of 800x109/L was found for predicting disease activity in PsA.SII may be an easy, practical, economical, and readily accessible tool for monitoring disease activity and the efficacy of treatment in PsA patients.Blood cell count, Psoriatic arthritis, Systematic immune inflammation index (SII).