Randomisation and blinding
WEST, RECRUITMENT
General practice sites were the units of allocation. A statistician blinded to the identity of practices randomised them on a 1:1 basis to deliver either the TRIUMPH intervention or usual care. Randomisation was performed after the practices had completed screening of patients and sent out invitations to eligible participants. Randomisation was minimised by centre (West of England and Wessex Clinical Research Network regions), practice size (number of registered patients), and area level deprivation of the practice (index of multiple deprivation score). We incorporated a random element into the minimisation procedure such that there was a 40% probability that allocation was random, with a 50-50 chance of practices being allocated to either arm. Area level deprivation assessed at the lower super output area level (geography comprising between 400 and 1200 households) can estimate deprivation for individuals (using home postcodes to identify the lower super output area level), but middle layer super output area level (geography made up of four or five lower super output area level) data better reflect the area level deprivation of general practices because the catchment area of a general practice is generally wider than the area covered by the lower super output area level.To minimise selection and recruitment bias, staff who conducted telephone calls for patient eligibility were blinded to practice allocation. Participants were blinded to their allocation until they had completed the baseline questionnaire and provided a signed consent form.