Effect of the intervention on adherence to the guideline for the behaviours x-ray referral, imaging referral, advice re activity and bed rest, as measured by the vignettes, using different effect metrics.

1All models adjusted for design strata and confounders specified prior to undertaking the analysis. See Table 4 for details of the design strata and confounders. The exception to this was “Bed rest adherence” which, due to limited events of non-adherence, was fitted with no adjustment for design strata and confounders. 2Metrics (RR and RD) calculated from marginal probabilities [62]. Confidence intervals for the metric were bootstrapped in Stata [65] allowing for clustering of observations within general practices (using both the cluster() and idcluster() options). Bias corrected 95% confidence intervals were calculated from 1000 replicates. 3CI limits could only be calculated from 612 bootstrapped replicates.