Baseline summary statistics of the behavioural constructs for the clinical behaviours ‘managing patients without referral for plain x-ray’ and ‘advising patients to stay active’1.

GPs: general practitioners; IQR: interquartile range; SD: standard deviation.1For all outcomes (except fear-avoidance beliefs) a larger score indicates greater agreement or likelihood in the practitioners’ intentions and beliefs in performing the particular behaviour (i.e. not referring for plain x-ray or advising patients to stay active). For example, a larger score on the behavioural construct “Attitudes (direct)” for managing patients without referral for plain x-ray indicates that the practitioner is more in favour of performing this behaviour. For the fear-avoidance beliefs scale, a larger score indicates greater fear avoidance beliefs surrounding physical activity and pain in acute non-specific low back pain.2Except for variables “perceived behavioural control (indirect)” and “fear-avoidance beliefs” where N = 55.3Behavioural intention performance for managing patients without referral for x-ray was reverse coded for consistency with the interpretation of the other behavioural constructs.4Construct measured directly (e.g. by asking GPs about their overall attitude) and indirectly (e.g. by asking about specific behavioural beliefs).5Perceived behavioural control (indirect) is a function of control belief items multiplied by control power items and can range from negative to positive values, with larger positive scores indicating greater perceived control over the behaviour.