BackgroundPediatric Inflammatory Multisystem Syndrome Associated With SARS-CoV-2 (PIMS) is a new insidious disease which in several points may mimic Kawasaki disease. Patients diagnosed with one of the aforementioned conditions are initially treated with intravenous immunoglobulin (IVIG). However, up to 20% of children diagnosed with Kawasaki disease appear to be resistant to such therapy. Similarly, substantial portion of PIMS patients requires second line treatment including systemic glucocorticoids. There are several calculative models, including the Kobayashi Score, which are utilized to predict patients’ response to such treatment. To our best knowledge, the scoring systems derived from Kawasaki disease have not yet been assessed whether they can fulfil similar role in PIMS patients.ObjectivesThere were two essential questions to be addressed in the study: (1) Can the Kobayashi Score be utilized in making clinical decisions regarding concomitant treatment in PIMS patients? (2) Is there any modification that may increase the accuracy of the original score?MethodsFirst step of the study involved 19 patients diagnosed with PIMS between July 2020 and June 2021. The statistical analysis including each parameter of the Kobayashi Score has been performed in order to determine potential alterations of the score. Then, the numerous variants of modified score have been compared in terms of their positive and negative predictive values in order to determine new PIMS IVIG Resistance Score (PIRS). In the next phase of the study, both scores have been validated in the second cohort involving 16 patients diagnosed with PIMS between July and December 2021. The final assessment has been performed in the unified study group (35 PIMS patients).ResultsThe Kobayashi Score (see Table 1) significantly differentiated PIMS patients in terms of good response or resistance to IVIG (p=0.03967). However, the score returned a few false positive (3 out of 9) and false negative (2 out of 10) results. After step-by-step verification of clinical and laboratory parameters, authors developed a tentative PIRS (see Table 1) including the following criteria: hyponatremia, days of fever and platelet count (derived from the Kobayashi Score but with different cut-off levels) supplemented with procalcitonin level and percentage of lymphocytes. In the validatory phase of the study, both scores had equal accuracy to predict treatment response. The analysis of receiver operating characteristic curve in the unified study group has shown better performance of PIRS (Youden index 0,72) than the Kobayashi Score (Youden index 0,49).Table 1.List of criteria included in both scores assessed in the study.CriteriaThe Kobayashi ScorePIMS IVIG Resistance Score (PIRS)Sodium≤133 mmol/L2 points≤137 mmol/L1 pointDays of illness at initial treatment≤42 points≤42 pointsAspartate aminotransferase≥100 IU/L2 points--Percentage of neutrophils≥80%2 points--Percentage of lymphocytes--≤16%1 pointC-reactive protein≥100 mg/L1 point--Procalcitonin--≥3.5 ng/mL1 pointAge≤12 months1 point--Platelet count≤300 G/L1 point≤200 G/L2 pointsIncreased risk of resistance to IVIG≥4 points≥4 pointsConclusionThe Kobayashi Score is worth being considered to estimate the risk of resistance to IVIG in PIMS patients. Nonetheless, it is not free from false positive and false negative results. The postulated modified score called PIRS can become a promising alternative but it requires further validation in larger cohorts of patients.Disclosure of InterestsNone declared