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Meta-Analysis
. 2021 Aug 10;15(8):e0009657.
doi: 10.1371/journal.pntd.0009657. eCollection 2021 Aug.

The 20-minute whole blood clotting test (20WBCT) for snakebite coagulopathy-A systematic review and meta-analysis of diagnostic test accuracy

Thomas Lamb  1   2 , Michael Abouyannis  3   4 , Sâmella Silva de Oliveira  5   6 , Rachana Shenoy K  7 , Tulasi Geevar  7 , Anand Zachariah  7 , Sanjib Kumar Sharma  8 , Navin Bhatt  9 , Mavuto Mukaka  2   10 , Eli Harriss  11 , David G Lalloo  3 , Elizabeth A Ashley  1   2   12 , Wuelton Marcelo Monteiro  5   6 , Frank Smithuis  1   2 , Michael Eddleston  13   14
Affiliations
Meta-Analysis

The 20-minute whole blood clotting test (20WBCT) for snakebite coagulopathy-A systematic review and meta-analysis of diagnostic test accuracy

Thomas Lamb et al. PLoS Negl Trop Dis. .

Erratum in

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.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. PRISMA-DTA flow chart.
The data from the 15 studies, with 2,270 patients, included in the systematic review are summarized in Table 1. These studies report data from Thailand (n = 4), India (3), Sri Lanka (3), Brazil (2), Nepal (2) and Papua New Guinea (1), on a variety of different snake genera: Daboia (n = 7), Trimeresurus (5), Hypnale (3), Echis (2), Bothrops (2), Calloselasma (1), Ovophis (1), Bungarus (1) and Oxyuranus (1). In several studies, snake genus and species was unknown.
Fig 2
Fig 2. Forrest plot of 20WBCT sensitivity and specificity at detecting coagulopathy, Forrest plot of 20WBCT sensitivity and specificity at detecting coagulopathy defined as INR>1·4.
Studies displayed individually and pooled. Circle size is proportional to sample size, whiskers represent 95% confidence interval.
Fig 3
Fig 3. SROC curve for 20WBCT at detecting coagulopathy.
SROC curves for 20WBCT at detecting mild coagulopathy defined as INR>1·4.
Fig 4
Fig 4. Forrest plot of 20WBCT sensitivity and specificity at detecting coagulopathy defined as fibrinogen < 100mg/dL.
Studies displayed individually and pooled. Circle size is proportional to sample size, whiskers represent 95% confidence interval.
Fig 5
Fig 5. SROC curve for 20WBCT at detecting coagulopathy.
SROC curves for 20WBCT at detecting mild coagulopathy defined as fibrinogen <100 mg/dL.
Fig 6
Fig 6. A density plot displaying the distribution of false negative and true positive 20WBCT results using a reference test of INR.
Fig 7
Fig 7. A density plot displaying the distribution of false negative and true positive 20WBCT results using a reference test of fibrinogen.
Fig 8
Fig 8. SROC curve for 20WBCT at detecting coagulopathy.
SROC curves for 20WBCT at detecting severe coagulopathy defined as INR>5 or fibrinogen <50 mg/dL.
See this image and copyright information in PMC

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