Table 2 The quality of included studies were evaluated by the Agency for Healthcare Research and Quality

1.Define the source of information (survey, record review)

Yes

Yes

Yes

Yes

Yes

2. List inclusion and exclusion criteria for exposed and unexposed subjects (cases and controls) or refer to previous publications

Yes

Yes

Yes

Yes

Yes

3. Indicate time period used for identifying patients

Yes

No

Yes

Yes

Yes

4. Indicate whether or not subjects were consecutive if not population-based

Yes

Yes

Yes

Yes

Yes

5. Indicate if evaluators of subjective components of study were masked to other aspects of the status of the participants

Yes

Yes

Yes

Yes

Yes

6. Describe any assessments undertaken for quality assurance purposes (e.g., test/retest of primary outcome measurements)

Yes

Yes

Yes

Yes

Yes

7. Explain any patient exclusions from analysis

Yes

Yes

Yes

Yes

Yes

8. Describe how confounding was assessed and/or controlled

Yes

Yes

Yes

Yes

Yes

9. If applicable, explain how missing data were handled in the analysis

Unclear

Unclear

Unclear

Unclear

Unclear

10. Summarize patient response rates and completeness of data collection

Yes

Yes

Yes

Yes

Yes

11. Clarify what follow-up, if any, was expected and the percentage of patients for which incomplete data or follow-up was obtained

Unclear

Unclear

Unclear

Unclear

Unclear

Total score

9

8

9

9

9