| Berner 2006 |
“The chosen procedure bases on the assumption, that agents are comparable through their relative effect vs. a common comparator” (methods). |
| Boonen 2007 |
“The validity of an adjusted indirect comparison depends on the internal validity of the RCTs involved. The methodology assumes similarity in trial design and methodological quality. Another assumption is that the magnitude of the treatment effect is consistent in patients across different trials” (discussion). |
| Chou 2006 |
“that the relative effect of one treatment compared with another is consistent across the entire set of trials” (introduction). |
| Clark 2004 |
“For the adjusted indirect comparison to be valid, the key underlying assumption is that the relative efficacy of an intervention is consistent in patients included in different trials; that is, that the estimated relative efficacy is generalisable” (results). |
| Collins 2007 |
“However, this method is only valid when the magnitude of the treatment effect is consistent between the different studies being compared” (appendix). |
| Hochberg 2003 |
“The authors did note that there were several assumptions that should be fulfilled in order to support the inferences drawn from these comparisons, including similarity of methodology in trial design and measurement of clinically important outcomes, and consistency of treatment effect in different subgroups of patients” (discussion). |
| Jones 2004 |
“However, the method is only valid when the magnitude of the treatment effect is consistent between the different studies being compared” (results). |
| Lim 2003 |
“The validity of indirect comparison meta-analysis is built on the assumption that no important differences exist between trials examining medium or low dose regimens. If the two sets of trials differ with respect to a feature (clinical or methodological) that modified the treatment effect, then the comparisons of medium and low dose aspirin would be confounded” (discussion). |
| Otoul 2005 |
“In order for this indirect comparison to be valid, the overall characteristics of the trials included in the meta-analyses could not differ systematically. The main statistical assumption in this adjusted method is that the relative effect of a drug is consistent; i.e., the odds ratio is the same in patients included in different trials” (methods). |
| Sauriol 2001 |
“The indirect approach to meta-analysis requires certain conditions to yield optimal results. For example, it is important that study designs, patient inclusion/exclusion criteria, and patient characteristics at baseline are as similar as possible across studies. Heterogeneity in study design or study population can lead to heterogeneity in results, and may lead to nonvalid conclusions. Therefore, the use of such methods does not always lead to the same conclusions” (discussion). |
| Zhou 2006 |
“The presence of clinical heterogeneity in these trials was evident; however, results from meta-analysis and substudies, particularly those using individual patient data, have indicated that the RR reduction of cardiovascular events by statin did not depend on the patients' risk stratified by age, sex, CHD history, and other cardiovascular risk factors. This consistency in the effect across different baseline characteristics is also required by the method of adjusted indirect comparison to ensure valid results” (discussion). |
