Table 2.
Evaluation of the risk of bias in included primary studies.
| Study ID | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Q9 | Q10 | Overall risk of study bias |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Albasri et al. 2018 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Albasri et al. 2019 | High risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Alakloby 2005 | High risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Ahmed et al. 2016 | High risk | High risk | High risk | Low risk | Low risk | Low risk | High risk | Low risk | Low risk | Low risk | Moderate risk |
| Alghanmi et al. 2013 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Al-Maghrabi et al. 2004 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Al-Saeed et al. 2006 | High risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | High risk | Low risk | Low risk |
| Al Shammrie et al. 2017 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | High risk | Low risk | Low risk |
| Alshammari et al. 2018 | High risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Alshamrani et al. 2019 | High risk | Low risk | Low risk | Low risk | High risk | Low risk | Low risk | Low risk | High risk | Low risk | Low risk |
| Al Shobaili 2010 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Bahamdan et al. 1995 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Parthasaradhi et al. 1998 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Shelleh et al. 2004 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
List of the 10 questions (Q1–Q10) applied to the studies: Q1. Was the study's target population a close representation of the national population in relation to relevant variables, e.g., age, sex, occupation? Q2. Was the sampling frame a true or close representation of the target population? Q3. Was some form of random selection used to select the sample, OR, was a census undertaken? Q4. Was the likelihood of nonresponse bias minimal? Q5. Were data collected directly from the subjects (as opposed to a proxy)? Q6. Was an acceptable case definition used in the study? Q7. Was the study instrument that measured the parameter of interest shown to have reliability and validity (if necessary)? Q8. Was the same mode of data collection used for all subjects? Q9. Was the length of the shortest prevalence period for the parameter of interest appropriate? Q10. Were the numerator(s) and denominator(s) for the parameter of interest appropriate?