PMC:4137988 / 10075-10806 JSONTXT

{"project":"2_test","denotations":[{"id":"25143747-19845575-55576477","span":{"begin":215,"end":217},"obj":"19845575"},{"id":"25143747-23157561-55576478","span":{"begin":521,"end":523},"obj":"23157561"}],"text":"Scientific quality\nOne19 of the 31 studies was published as a conference abstract only and was not included in our quality review. Twenty-eight studies were rated positive (scoring 8 or 9 out of 10; Tables 2–4). One20 of the two studies rated as neutral was a case-control study that received a quality score of 8, but did not clearly describe whether potential confounding factors were comparable for the cases and controls, although the potential confounding variables were adjusted for in the analyses. The other study21 was a randomized controlled trial (RCT) that did not clearly describe the method of randomization or the amount of exposure to intervention. No study was excluded from meta-analysis based on quality ratings."}