20-minute whole blood clotting test systematic review
Study title: The 20-minute whole blood clotting test (20WBCT) for snakebite coagulopathy - a systematic review and meta-analysis of diagnostic test accuracy. Abstract: Background The 20-minute whole blood clotting test (20WBCT) has been used to detect coagulopathy following snakebite for almost 50 years. A systematic review and meta-analysis of the 20WBCT was conducted to evaluate the accuracy of the 20WBCT to detect coagulopathy, indicative of systemic envenoming. Methods and findings Databases were searched from inception up to 09/12/2020 to identify studies that compared the 20WBCT and INR/fibrinogen on five or more subjects. Data was extracted from full-text articles by two reviewers using a predetermined form. Authors of 29 studies that lacked sufficient details in the manuscript were contacted and included if data meeting the inclusion criteria were provided. Included studies were evaluated for bias using a tailored QUADAS-2 checklist. The study protocol was prospectively registered on PROSPERO database (CRD42020168953). The searches identified 3,599 studies, 15 met the inclusion criteria and 12 were included in the meta-analysis. Data was reported from 6 countries and included a total of 2,270 patients. The aggregate weighted sensitivity of the 20WBCT at detecting INR >1.4 was 0.84 (CI 0.61 to 0.94), the specificity was 0.91 (0.76 to 0.97) and the SROC AUC was 0.94 (CI 0.91 to 0.96). The aggregate weighted sensitivity of the 20WBCT at detecting fibrinogen <100 mg/dL was 0.72 (CI 0.58 to 0.83), the specificity was 0.94 (CI 0.88 to 0.98) and the SROC AUC was 0.93 (0.91 to 0.95). Both analyses that used INR and fibrinogen as the reference test displayed considerable heterogeneity. Conclusions In the absence of laboratory clotting assays, the 20WBCT remains a highly specific and fairly sensitive bedside test at detecting coagulopathy following snakebite. However, clinicians should be aware of the importance of operator training, standardized equipment and the lower sensitivity of the 20WBCT at detecting mild coagulopathy and resolution of coagulopathy following antivenom. The data includes Individual patients values from seven studies included in the systematic review. Institutions are anonymous at the request of the host researchers. 20WBCT_SR_repository_1 includes cleaned data used to perform meta-analysis 20WBCT_IDP includes cleaned data provided by six primary authors. This data (in addition to data extracted from figures in a further two publications (Ratnayake et al 2017 and Sano-martins et al 1994) was used to calculate the secondary analyses (severe coagulopathy and comparisons of false negatives and true positives). The authors from one study declined permission to deposit their individual patient data. 20WBCT_IDP+6-12h This data was used to calculate the secondary analysis at assessing the sensitivity and specificity after antivenom.