Table 3.

Risk of bias assessed by the Joanna Briggs Institute (JBI) Critical Appraisal Tools.

Authors	Q1	Q2	Q3	Q4	Q5	Q6	Q7	Q8	% Yes	Risk
Jell et al. (18)	−	√	√	−	√	−	√	√	62.5%	Moderate
Brantberg et al. ‘90 (16)	√	√	√	√	√	−	√	√	87.5%	Low
Brantberg et al. ‘91 (15)	√	√	√	√	√	−	√	√	87.5%	Low
Hain et al. ‘91 (19)	√	√	√	√	−	−	√	√	75%	Low
Hain et al. ‘92 (20)	√	√	√	√	−	−	√	√	75%	Low
Dellepiane et al. (21)	−	√	√	−	−	−	√	√	50%	Moderate
Zasorin (17)	√	√	√	√	√	−	√	√	87.5%	Low

√ Yes; − No;

Q1. Were the criteria for inclusion in the sample clearly defined?

Q2. Were the study subjects and the setting described in detail?

Q3. Was the exposure measured in a valid and reliable way?

Q4. Were objective, standard criteria used for measurement of the condition?

Q5. Were confounding factors identified?

Q6. Were strategies to deal with confounding factors stated?

Q7. Were the outcomes measured in a valid and reliable way?

Q8. Was appropriate statistical analysis used?