Table 1. Studies included in the systematic review.
| First author, year | Country | Funding source/ Declaration | Snake species | Method of snake identification | Median (IQR) time to hospital | Reference test | Number of 20WBCT | True positive | False negative | True negative | False positive | Sensitivity (Confidence interval) | Specificity (Confidence interval) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Thongtonyong [32], 2020 | Thailand | NR / No conflict of interest | Calloselasma rhodostoma | Dead snake and photographs | 1.2 h (IQR NR | fibrinogen <100 mg/dL | 296 | 98 | 23 | 158 | 17 | 0·81 (0·73–0·88) | 0·90 (0·85–0·94) |
| Wijewickrama [31], * 2020 | Sri Lanka | NMHRC/ No conflict of interest | Hypnale spp and Daboia russelli | Enzyme immunoassay (EIA) | 1.0 h (0.5–2.5) | INR > 1·4 | 157 | 5 | 11 | 130 | 11 | 0·31 (0·11–0·59) | 0·92 (0·86–0·96) |
| Tongpoo [33], 2020 | Thailand | RHMU/ No conflicts of interest | Trimeresurus spp | Dead snake and syndrome | 1.3 h (IQR NR) | fibrinogen < 100 mg/dL | 38 | 4 | 8 | 26 | 0 | 0·33 (0·10–0·65) | 1·00 (0·87–1·00) |
| Bhatt, * 2020 | Nepal | NR/NR | Ovophis monticola and Trimeresurus spp | Dead snakes and photographs | NR | INR >1·4 | 97 | 20 | 1 | 55 | 21 | 0·95 (0·76–1·00) | 0.72 (0·61–0·82) |
| Sharma, * 2020 | Nepal | NR/NR | Daboia russelli and Trimeresurus spp | Dead snakes and photographs | NR | INR >1·4 | 33 | 8 | 1 | 24 | 0 | 0·89 (0·52–1·00) | 1·00 (0·86–1·00) |
| Shenoy [16], ‡ 2020 | India | CMC Vellore/ No conflicts of interest | Daboia russelli and Echis carinatus | Not specified | NR | INR >1·4 | 66 | 24 | 1 | 32 | 9 | 0·96 (0·80–1·00) | 0·78 (0·62–0·89) |
| Dsilva [34], 2019 | India | NR/ No conflicts of interest | Daboia russelli and Echis carinatus | Not specified | NR | INR >1·4 | 60 | 8 | 3 | 35 | 14 | 0·73 (0·39–0·94) | 0·71 (0·57–0·83) |
| Saengnoi [35], 2019 | Thailand | RHMU/ No conflicts of interest | Trimeresurus spp and Daboia siamensis | Dead snakes and photographs | NR | fibrinogen <100 mg/dL | 48 | 0 | 1 | 43 | 4 | 0·00 (0·00–0·98) | 0.91 (0·80–0·98) |
| Oliveira [5], * 2019 | Brazil | CAPES, CNPQ and FAPEAM/ No conflicts of interest | Bothrops spp | Dead snakes and EIA | NR | fibrinogen <100 mg/dL | 100 | 54 | 26 | 20 | 0 | 0·68 (0·56–0·78) | 1·00 (0·83–1·00) |
| Silva [14], † 2018 | Sri Lanka | NR/NR | Daboia russelli, Hypnale hypnale, and Bungarus caeruleus | Dead snakes | NR | INR >1·5 | 92 | 14 | 12 | 62 | 4 | 0·54 (0·33–0·73) | 0.94 (0·85–0·98) |
| Ratnayake [36], 2017 | Sri Lanka | NMHRC/ No conflicts of interest | Daboia russelli and Hypnale spp | Dead snakes and EIA | NR | INR >1·4 | 987 | 65 | 14 | 895 | 13 | 0·82 (0·72–0·90) | 0·99 (0·98–0·99) |
| Biradar [28], 2015 | India | None/ No conflicts of interest | Not specified | Dead snakes, photographs or toxidrome | NR | INR >1·5 | 112 | 33 | 33 | 41 | 5 | 0·50 (0·37–0·63) | 0·89 (0·76–0·96) |
| Paiva [29], † 2015 | Papua New Guinea | NR/NR | Oxyuranus scuttelatus | Not specified | NR | fibrinogen <50 mg/dL | 60 | NR | NR | NR | NR | 0·93 | 0·91 |
| Pongpit [12], 2012 | Thailand | TRF and CHEMET/ No conflicts of interest | Trimeresus albolabris and T. macrops | Dead snake or visualisation of green snake | NR | fibrinogen <100mg/dL | 55 | 6 | 1 | 46 | 2 | 0·86 (0·42–1·00) | 0·96 (0·86–0·99) |
| Sano-martins [37], 1994 | Brazil | STDEPC/NR | Bothrops spp | Dead snake and EIA | NR | fibrinogen <100mg/dL | 69 | 37 | 7 | 23 | 3 | 0·84 (0·70–0·93) | 0.88 (0·70–0·98) |
Key: * Data included from study that did not assess the validity of 20WBCT as primary objective
† Conference abstract
‡ Published MD thesis in repository. NR = Not reported, NHMRC = Australian National Health and Medical Research Council, RHMU = Ramanthibodi Hospital Mahidol Univeristy, CMC = Christian Medical College, CAPES = Coordenção de Aperfeiçoamento de Pessoal de Vível Superior, CNPQ = Conselho Nacional de Desenvolvimento Científico e Tecnológico, FAPEAM = Fundação de Amparo à Pesquisa do Estado do Amozonas, TRF = Thailand Research Fund, CHEMET = Commission on Higher Education, Ministry of Education, Thailand and STDEPC = Science and Technology for Development Programme of the European Community.