External validation of 4C ISARIC mortality score in the setting of a Saudi Arabian ICU. Retrospective study.

Mumtaz, S. A.; Shahzad, S. A.; Ahmed, I.; Alodat, M. A.; Gharba, M.; Saif, Z. A.; Mady, A. F.; Mahmood, W.; Mhawish, H.; Abdulmowla, M. M.; Aletreby, W. T.

COVID-19 pandemic has burdened healthcare systems, necessitating the development of mortality prediction scores to guide clinical decisions and resource allocation. 4C ISARIC mortality score was developed and validated on a British cohort. Objectives: External validation of the score in the setting of a large Saudi Arabian ICU. Method: Retrospective chart review of COVID 19 patients admitted to ICU of King Saud Medical City, Riyadh, Saudi Arabia. Collecting data to calculate the score, then fitting a ROC curve against known patients outcome. Results: Cohort included 1493 patients with 38% mortality, AUC of the score was 0.81 (95% CI: 0.79 to 0.83, p < 0.001), correctly classifying 72.67% of the cohort. Cutoff value of > 9 had sensitivity of 70.5% (95% CI: 66.6 to 74.3), specificity 73.97% (95% CI: 71 to 76.8), positive predictive value 62.4% (95% CI: 59.5 to 65.2), and negative predictive value 80.2% (95% CI: 78.2 to 82.4). Conclusion: 4C ISARIC mortality risk score performed well with a good discriminatory ability for critically ill patients admitted to ICU in our setting. Cut-off > 9 was the optimal criterion.