Table 2 Questions on contacting of authors for the survey

Title of the systematic review

Question 1. Could you please insert the title of your review?

 (Please copy and paste your review title from our email)

 Answer 1. Insert title: ……………………………………………………………………………………..

Contacting of the eligible included studies for additional information

Question 2. Did you contact any of the study authors of the eligible studies in your review to obtain additional information (e.g., issues on risk of bias and unclear or missing data) on these included studies?

 Please assess carefully the possible answers to this question:

 Yes: If you contacted (through mail, telephone etc.) one or more authors of the eligible studies in your review to obtain additional information on these included studies (e.g., issues on risk of bias, unclear, or missing data).

 No: When authors were not contacted or when authors were contacted for other reasons e.g., to verify potential eligibility of studies or to obtain information on unknown completed or ongoing studies.

 Answer 2. Yes or no

Valid contact data

Question 3. Had all contacted studies valid contact data?

 Please assess carefully the possible answers to this question:

 Valid contact data refers to having one or more of the following functioning contact data, i.e., email addresses, telephone numbers, fax numbers, and postal addresses.

 Answer 3. Yes or no

Effect on risk of bias scores

Question 4. Were one or more risk of bias scores in your review modified as a result of the information obtained from contacted studies?

 Please assess carefully the possible answers to this question:

 Yes: One or more risk of bias scores in your review were modified as a result of the information obtained from the contacted studies.

 No: None of the risk of bias scores in your review were modified as a result of the information obtained from the contacted studies.

 Not applicable: Risk of bias was not assessed in your review or this question could not be addressed for other reasons.

 Answer 4. Yes, no, not applicable

Effect on the GRADE score

Question 5. Were GRADE scores for one or more outcomes modified as a result of the information obtained from the contacted studies?

 Please assess carefully the possible answers to this question:

 Yes: GRADE scores for one or more outcomes were modified as a result of the information obtained from the contacted studies.

 No: GRADE scores for one or more outcomes were not modified as a result of the information obtained from the contacted studies.

 Not applicable: GRADE scores were not assessed in your review or this question could not be addressed for other reasons.

 Answer 5. Yes, no, not applicable

Effect on the summary primary or secondary outcomes

Question 6. Were any of the summary primary or secondary outcomes of the review modified as a result of the information obtained from the contacted studies?

 Please assess carefully the possible answers to this question:

 Yes: One or more summary primary or secondary outcomes of the review were modified as a result of the information obtained from the contacted studies.

 No: None of the summary primary or secondary outcomes of the review were modified as a result of the information obtained from the contacted studies.

 Answer 6. Yes or no

Effect on the summary effect size of the primary outcome

Question 7. How was the summary effect size of the primary outcome modified as a result of the information obtained from the contacted studies?

 Please assess carefully the possible answers to this question:

 Increased: The summary effect size of the primary outcome increased as a result of the information obtained from the contacted studies.

 Decreased: The summary effect size of the primary outcome decreased as a result of the information obtained from the contacted studies.

 Unchanged: The summary effect size of the primary outcome did not change as a result of the information obtained from the contacted studies.

 Not applicable: The summary effect size of the primary outcome was not measured in your review or this question could not be addressed for other reasons.

 Answer 7. Increased, decreased, unchanged, not applicable

Optional question

Question 8. Could you please describe some issues that you want to share with us regarding contacting of study authors of the eligible studies included in your review?

 Answer 8. I have the following issues to share:

 I have no further issues to share.