A New Score for Predicting Mortality in Crimean-Congo Hemorrhagic Fever Associating CURB-65 with Bleeding: CURB-65+B

Abstract

The clinical spectrum of Crimean-Congo hemorrhagic fever (CCHF) disease ranges from mild to fatal. Adult patients infected with the CCHF virus have a case fatality rate ranging from 3% to 30%. In order to measure the severity and mortality of CCHF disease, scoring systems comprised of laboratory data and clinical observations have been developed. In this study, it was aimed to develop a scoring system that was easy to use and reliable, with parameters that are often looked at in clinical practice to predict mortality in CCHF disease. For this purpose, a new scoring system that combines CURB-65 and bleeding (CURB-65+B) was developed. The mortality prediction performance of this score in CCHF disease was evaluated. This study was conducted as a retrospective, single-center study in patients diagnosed with CCHF in a tertiary care hospital in a region where CCHF is endemic between April 2016 and October 2022. Five hundred patients with verified polymerase chain reaction (PCR) and/or IgM positive for CCHF were included in the study. In the CURB-65+B score, variables believed to be related with mortality; such as confusion, elevated urea, tachypnea, hypotension, age 65 or older, and the presence of bleeding, were assessed. The CURB-65+B scores of the patients were calculated and evaluated at the time of admission to the hospital. The median age of the included patients was 48, and 302 (60.4% of the total) were male. Bleeding was observed in 136 (27.2%) and mortality was observed in 17 (3.4%) of the patients. At the time of hospital admission, a CURB-65+B score that was more than three points was found to be a significant factor in predicting mortality. Among the initially evaluated laboratory parameters, bleeding, CURB-65 and CURB-65+B scores, the indicator with the highest predictive power for mortality was the CURB-65+B score with a cut-off value of above 3 points. The sensitivity of the CURB-65+B score was 88.2%, and the specificity was 95.9%. The predictive power of the score for mortality was 0.972. It was observed that the CURB-65+B score has a high predictive power in CCHF disease mortality. If the CURB-65+B score was higher than three points, it was discovered that the Kaplan-Meier survival analysis would have resulted in a 25.57-times shorter survival time and considerably lower survival times. In addition it was observed that, there was no mortality observed in any of the patients who had a score of 0 on the CURB-65+B score. As a result, in our study, it was determined that the CURB65+B score could be a useful, reliable and practical tool to easily calculate the mortality of CCHF patients during hospital admission and to guide the referral processes related to patient triage.