Table 1 Risk of bias assessment tool.
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 |