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Table 1 Risk of bias assessment tool.

From: The neglected burden of snakebites in Cameroon: a review of the epidemiology, management and public health challenges

Risk of bias item Response: yes (low risk) or no (high risk)
External validity  
1. Was the study target population a close representation of the national population in relation to relevant variables?  
2. Was the sampling frame a true or close representation of the target population?  
3. Was some form of random selection used to select the sample, OR, was a census undertaken?  
4. Was the likelihood of non-participation bias minimal?  
Internal validity  
5. Were data collected directly from the participants (as opposed to medical records)?  
6. Were acceptable case definitions of snakebite used?  
7. Were reliable and accepted diagnostic methods for snake envenomation utilised?  
8. Was the same mode of data collection used for all participants?  
9. Was the length of the shortest prevalence period for the parameter of interest appropriate?  
10. Were the numerator(s) and denominator(s) for the calculation of the prevalence of snakebite appropriate?  
11. Summary item on the overall risk of study bias  
Low risk of bias 8 or more ‘yes’ answers  
Further research is very unlikely to change our confidence in the estimate  
Moderate risk of bias 6 to 7 ‘yes’ answers. Further research is likely to have an important impact on our confidence in the estimate and may change the estimate  
High risk of bias 5 or fewer ‘yes’ answers  
Further research is very likely to have an important impact on our confidence in the estimate and is likely to change the estimate