Summary of quality assessment criteria.

(1)Yes: method preserves randomization. No: method does not preserve randomization.
(2)Yes: reported a method that is stated will assess the assumption of similarity. No: do not report a method.
(3)Yes: sensitivity analysis, subgroup analysis, or meta-regression used to assess consistency of the indirect comparison across different trial or patient characteristics. No: no method, no analysis that includes all the trials in the indirect comparison. Unclear: unclear if the trials used in the analysis are the same trial sets involved in the indirect comparison.
(4)Yes: Chi-square test, I-squared statistic, estimating the between trial variance from a random effects models. No: no method applied, or not applied to the two trial sets contributing to the indirect comparison. Unclear: unclear if heterogeneity was assessed for the two trial sets contributing to the indirect comparison. Not applicable: only one trial in each trial set.
(5)Yes: no heterogeneity present (reported by authors or determined from the results), or accounted for heterogeneity using the random effects model. No: heterogeneity not accounted for using the random effects model. Unclear: unclear if heterogeneity present, or unclear if heterogeneity taken into account using the random effects model. Not applicable: only one trial in each trial set.
(6)Yes: sensitivity analysis, subgroup analysis, or meta-regression used to assess homogeneity across different trial or patient characteristics within each of the two trials sets involved in the indirect comparison. No: no method, no analysis that includes the trials in each of the two trial sets involved in the indirect comparison. Unclear: unclear if the trials used in the sensitivity analysis, subgroup analysis, or meta-regression are the same set of trials as those in each of the two trial sets involved in the indirect comparison. Not applicable: only one trial in each trial set; or homogeneity assumption satisfied.
(7)–(14)Not applicable: both indirect and direct evidence are not presented for the same comparison.
(8)Not applicable: reported to be inconsistent, or unclear if consistent based on text or results.
(9)Not applicable: reported to be consistent, or unclear if inconsistent based on text or results.
(12)Yes: three-arm trials are correctly analysed i.e. indirect evidence (AC, BC) is not included and direct evidence (AB) is analysed, and data from a three-arm trial is not combined as though it is from two different studies. No: three-arm trials are incorrectly analysed i.e. indirect evidence (AC, BC) is included and direct evidence (AB) is not analysed, or data from a three-arm trial is combined as though it is from two different studies. Na: no three-arm trials are included in the review.
(15)Yes: the term indirect comparison is stated when referring to the result or the result is presented under a heading that states the result is based on an indirect comparison. No: result is presented without noting it is an indirect comparison.