2.2  Measures
Information concerning sociodemographic and socioeconomic factors, cardiovascular history and risk factors, patient's attribution of symptoms, clinical and proximal factors, and time of admission, symptom onset and call for assistance was collected using medical records and semi-structured interviews 2.6 ± 1.5 days after hospital admission. Socioeconomic position was assessed using educational qualifications which were categorized into 3 groups; high school/university qualification, below high school, or no formal educational qualifications of any kind. Patients were asked whether they initially attributed the pain to a heart attack or to a non-cardiac cause (e.g. indigestion, muscle strain, flu). Clinical data included type of ACS, which was classified as ST elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI) or unstable angina (UA); intensity of chest pain, rated on a 10 point scale (0 = none to 10 = excruciating); number and type of pain symptoms reported in addition to chest pain (i.e. pain in arms, shoulders, jaw, back) and non-pain symptoms (i.e. breathlessness, nausea/vomiting, sweating, flu-like, dizziness/fainting); cardiac history and risk factors. Proximal factors included time/day of onset, presence of a bystander and location, and a record was made of whether they initially contacted the EMS or another source of help such as a physician, family or friends.