BMC Public Health 2008, 8:126 http://www.biomedcentral.com/1471-2458/8/126 Random selection from target population of 300 each for 12 groups = 2 (LD &MD) x 2 (M & F) x 3 (35-44, 45-54 & 55- 64 yrs) = 3,600 103 subjects were excluded by the GPs as unsuitable for taking part in the study. LD = 20 (M=5, F=15) MD = 83 (M=48, F=35) Target Population = 21,672 (LD = 13,004; MD = 8,668) ref to Table 1 for breakdown by age & sex Not al subjects in the LD group were invited (as targets were met) but in the MD group extra numbers were generated to meet thetargets 224 Letters were returned as subject had moved or was not known at the address. LD = 49 (F=12,M=37), MD = 175 (F=39, M=136) Number of subjects contacted for the study = 2,936 Number of subjects not contactable = 224 Number of subjects invited to participate in the study = 2,712 See Figure 2 for breakdown by age, sex and deprivation) Number who attended Visit 1 = 700 (25.8%) Number who declined = 812 (29.9%) Participants withdrew after Visit 1 due to other commitments. LD = 12 (F=7, M=5) MD = 22 (F=13, M=9) Number who completed Visit 1 & Visit 2 = 666 (95.1%) Number who ONLY completed Visit 1 = 34 (4.9%) Number who did not respond = 1,200 (44.3%) LD = least deprived MD = most deprived M = Male F = Female RFiegcururietm1ent flowchart for the pSoBid study Recruitment flowchart for the pSoBid study. LD = Least Deprived; MD = Most Deprived. M = Male; F = Female. on performance and affective state would be those observed in real life. Psychology questionnaires completed by the participants at Visit 2 provided indices of personality and individual differences in self-esteem. The personality factor of neu- roticism is known significantly to affect emotional responsiveness and adjustment. Assessment involved self- completion of the Eysenck Personality Scales[48] and the Rosenberg Self-Esteem Scale[49]. Cognitive assessment involved the following main domains of cognition: exec- utive function (tested by Trails Test[50] and Stroop Test[51]), memory (tested by Auditory Verbal Learning Test) and cognitive performance (estimated from the NART-2[52] which provided a proxy measure of "IQ"). Attention and speed of processing were tested by Choice Reaction Time[53]. Male participants were asked if they would be interested in participating in MRI scanning (Visit 3). From a total of 327 male participants, 140 volunteered, and 40 of these were randomly selected (stratified by age group and deprivation category). These scans will be completed by spring 2008. Before each visit the participants were contacted by tele- phone on the previous day to confirm their attendance and to ensure that the taxi arrangements were in place. At the end of the study all participants were sent a letter thanking them for their participation in the study and were informed that they would all receive an executive summary of the study findings. After each visit partici- pants were asked to complete a feedback form detailing their opinion of the study and their experiences. Lifestyle questionnaire This questionnaire had 13 sections including basic demo- graphic data, past and present health status, current med- ications, oral health, smoking history, alcohol intake, diet, physical activity levels, childhood situation, birth weight and place of birth, their parents' age and father's occupation, education levels, employment history and income levels. Carotid intima media thickness Measurement of the intima media thickness of the carotid artery by high resolution ultrasound is now a widely accepted, non-invasive, surrogate measure of atheroscle- rosis and a reliable indicator of future risk of a major cor- onary event[54,55]. Carotid intima media thickness provides a suitable continuous outcome measure for atherosclerosis, enabling association studies to be per- formed on fewer numbers (i.e. hundreds of subjects com- pared to classical surveys using endpoints such as MI which require sample sizes in the thousands). Recent carotid intima media thickness studies have evaluated the extent to which sex differences in CHD are explained by central obesity, the relationship between degree of athero- sclerosis (intima media thickness) and inflammation sta- tus (CRP levels)[55,56] and the relationship of periodontal disease to carotid intima media thick- ness[57]. Ultrasound examination of the carotid arteries also allows presence and number of plaques to be deter- mined[58,59]. Carotid plaque count has previously been found to be a predictor of myocardial infarction[58] and stroke[60]. The carotid ultrasound examination lasted 20 to 30 minutes. Doppler velocity in right and left internal carotid arteries was recorded in order to identify any sig- nificant internal carotid artery stenosis. Images of the dis- tal 1 cm of the common carotid artery, the carotid bulb and the proximal internal carotid artery were recorded on the left and right side, and intima-media thickness of the far wall of the artery determined using the software pack- age Etrack. The number of carotid plaques at each of the six sites was determined using published procedures[58]. M-mode ultrasound of the distal common carotid artery was recorded to assess arterial stiffness. Reading of the scans was performed off-line by a reader who was blinded to the identity of the participants. Page 5 of 11 (page number not for citation purposes)