Eligible patients were identified from the practice roster of one family physician.
Smokers aged 20-70 years will be identified from the practice records and contacted by post by their GP.
In total, 2696 patients identified from the practice prescribing databases were eligible and invited to take part in the study; 504 (18.7%) agreed.
We included patients with coronary heart disease (CHD), e.g. myocardial infarction, angina pectoris or vascular surgery, who were identified from the practice records by the presence of a diagnosis code or active current medication.
A further three cases were identified from the practices of the authors.
Women aged 49 69 years were identified from the general practice registers.
With respect to case identification, the protocol specified that "the main analysis will be run on all cases with VTE identified from the general practice data".
The main analyses will be run on all cases with VTE identified from the general practice data and their matched controls.
Cases and controls were identified from the 10 practices which contributed consultation data to CiPCA for the entire study period (2000 to 2008).
All patients identified from the GP practices and Physio Direct are mailed a letter inviting them to telephone for an appointment at the Community Back Pain Clinic, along with a patient information leaflet about the Trial and a baseline questionnaire.
