Network meta-analyses: no compensation for weak evidence

Numerous biologics for the treatment of rheumatoid arthritis have been available for several years. What are the advantages and disadvantages of the individual drugs in combination with methotrexate compared with the other biologics? This is a question of great practical importance for such a common disease, but it is still difficult to answer – not least because, in most of the studies conducted for drug approvals, no other biologics were used in the comparator arms.

A team of authors headed by staff of the German Institute for Quality and Efficiency in Health Care (IQWiG) has now published a systematic review in the British Medical Journal in which they tried to reconstruct the comparisons missing in the individual studies using the tool of network meta-analysis (NMA). The NMA was primarily intended to remedy two shortcomings in previous meta-analyses on the same topic: the use of outdated definitions of endpoints and the comparison of patient groups that are too heterogeneous.

As becomes clear from both the systematic review and an opinion piece published at the same time, even the most rigorous NMA is not able to completely eliminate deficiencies in the underlying studies. Thanks to the re-analyses of individual patient data conducted by the study sponsors for this IQWiG assessment, at least the majority of available studies could be included in the network meta-analysis. Therefore, relevant endpoints according to current definitions could be examined in such an analysis for the first time. Beate Wieseler, Head of IQWiG’s Drug Assessment Department, notes: "Only individual patient data enable tailored re-analyses. These data should be made routinely available to researchers. In this way, the findings from individual studies can make a much greater contribution to better patient care".