- aIntention: X-ray referral is coded ‘Yes’ if the clinician ticked either “Lumbosacral plain X-ray” or “Full spine pain X-ray” in the vignette response questionnaire. Intention: imaging referral is coded ‘Yes’ if the clinician ticked “Lumbar CT scan”, “Lumbar MRI”, or “Bone Scan” in the vignette response questionnaire. Intention: advice to stay active is coded ‘Yes’ if the clinician ticked “Advice to stay active” in the vignette response questionnaire. Intention: advised bed rest is coded ‘Yes’ if the clinician indicated “Bed rest” for greater than 2 days in the vignette response questionnaire
- bEach clinician responded to four vignettes
- cAdjusted effects from models fitted using Generalised Estimating Equations with exchangeable correlation structure (unless otherwise noted) and robust variance estimation to allow for clustering within practices. OR = odds ratio. Models adjusted for pre-specified confounding variables noted in Fig. 2 of the trial protocol [22]
- dRD risk difference. RD calculated from marginal probabilities. Confidence intervals were calculated using a pairwise comparison of margins after fitting a GEE model using Stata, allowing for clustering of observations within practices
- eModelled with an independent correlation structure