BMC Public Health 2008, 8:126 http://www.biomedcentral.com/1471-2458/8/126 Deprivation Sex Age Groups % Attended Visit 1* Declined Least Deprived 1,008 Total Invited = 2,712 Most Deprived 1,704 Males = 527 Females = 481 Males = 962 Females = 742 35-44 yrs = 241 45-54 yrs = 167 55-64 yrs = 119 35-44 yrs = 181 45-54 yrs = 178 55-64 yrs = 122 35-44 yrs = 361 45-54 yrs = 321 55-64 yrs = 280 35-44 yrs = 318 45-54 yrs = 211 55-64 yrs = 213 22.4% 35.3% 52.9% 31.5% 33.7% 50.0% 14.1% 17.8% 20.4% 19.2% 28.4% 28.2% 30.7% 30.6% 26.1% 36.5% 41.6% 37.7% 15.5% 24.6% 41.1% 22.0% 32.7% 38.0% Non- Respondent 47.9% 34.1% 21.0% 32.0% 24.7% 12.3% 70.4% 57.6% 38.5% 58.8% 38.9% 33.8% BFaigsiucrceha2racteristics of subjects included in the pSoBid study by deprivation, sex and age Basic characteristics of subjects included in the pSoBid study by deprivation, sex and age. * = Included in these % are 34 participants who ONLY completed Visit 1. GPASS Extraction Process GPASS was used to evaluate the characteristics of those who were invited to participate in the study. Eight of the ten GP practices (four in the LD area, four in the MD area) selected for the study use GPASS to record their routine data. Anonymised data were collected on smoking status and current prescription for statins, aspirin, antihyperten- sives, antidepressants and anti-diabetic drugs as evidence of the prevalence of chronic disease. Data were collected separately for those who attended visit 1 (Group 1), those who declined to attend (Group 2) and non-respondents to the invitation (Group 3). Non-participants (Group 4) were defined as the combination of groups 2 and 3. Statistical analysis Sample size in the LD and MD groups was estimated on the assumption that 90% would attend both visits and have CRP measured and that a maximum of 10% would not have good quality intima media thickness measure- ments. The power calculations were based on perceived clinically meaningful differences and assumed a 1.1 mg/L standard deviation for the natural logarithm of CRP meas- urements[61] and a 0.163 mm standard deviation for carotid intima media thickness[62]. Power calculations indicated that a sample size of 350 per group would pro- vide 84% power to detect a 30% difference in mean CRP levels and 82% power to detect a 0.04 mm difference in mean carotid intima media thickness. Categorical data are presented as counts and where appro- priate as percentages. Where formal comparisons of per- centages have been carried out, chi-squared tests have been used. Results From the sampling frame of 3600 subjects a total of 2,712 invitations were issued to recruit a cohort of 700 (25.8%) participants. Out of the 2,712 invitations sent, 812 Page 6 of 11 (page number not for citation purposes)