A threshold analysis assessed the credibility of conclusions from network meta-analysis

Objective: To assess the reliability of treatment recommendations based on network meta-analysis (NMA)

Study design: We consider evidence in an NMA to be potentially biased. Taking each pair-wise contrast in turn we use a structured series of threshold analyses to ask: (a) “How large would the bias in this evidence-base have to be before it changed our decision?” and (b) “If the decision changed, what is the new recommendation?” We illustrate the method via two NMAs in which a GRADE assessment for NMAs has been implemented: weight-loss and osteoporosis.

Results. Four of the weight-loss NMA estimates were assessed as “low” and 6 as “moderate” quality by GRADE; for osteoporosis 6 were “low”, 9 “moderate” and 1 “high”. The threshold analysis suggests plausible bias in 3 of 10 estimates in the weight-loss network could have changed the treatment recommendation. For osteoporosis plausible bias in 6 of 16 estimates could change the recommendation. There was no relation between plausible bias changing a treatment recommendation and the original GRADE assessments.

Conclusions. Reliability judgements on individual NMA contrasts do not help decision makers understand whether a treatment recommendation is reliable. Threshold analysis reveals whether the final recommendation is robust against plausible degrees of bias in the data.