Lue 0.003,0.001 0.003,0.001 0.002 0.002,0.001 95% self-confidence interval 1.568.09 1.857.17 1.476.11 two.267.54 1.445.47 1.364.16 three.8319.90 391 101 237 425 three.23 two.66 five.96 5.96 ,0.001 0.003,0.001,0.001 1.726.04 1.395.09 three.2810.83 three.2810.83 289 180 284 1 four.64 7.48 0.010,0.001 1.4514.79 2.5821.68 the general population in other studies. Salokangas & Poutanen reported that risk factors for depression in the basic population were physical health problems, physical disability, and poor social support. Brown & Harris previously reported the association between social problems and the onset of depression. These associations were recognized by GPs, practice nurses and patients participating in qualitative studies as part of the UPBEAT-UK programme. However a novel finding, reflecting the nature of this population was that reporting still experiencing chest pain was one of the strongest associations with depression independent of associations with other pains and discomfort. The chest pain could be due to the underlying ischaemic heart disease or be a somatic symptom associated with the concurrent depression or perhaps both. Further analyses of our data will elucidate this. The prevalence of depressive disorder was lower than previously reported in one US study of people with CHD living in the community. Egede found a prevalence rate of depression in people with CHD of 15%. Possible explanations for the lower prevalence of depression in our study is response bias – patients with co-morbid depression or anxiety may be less likely to respond to the GP’s letter inviting participation in the study leading to an underestimation of the prevalence rate, but is also likely to represent the sensitivity of instruments used to detect depression. In our study we used the CIS-R as a `gold-standard’ as this generates ICD-10 diagnoses rather than the probability of depression based on symptom scores. When the HADS was used Variable CIS-R diagnosis of depression Problems living alone Experiences chest pain Disabled by pain and discomfort Problems carrying out usual activities Age at entry into the study GP case note diagnosis of depression Problems with close relationships Diabetes Mellitus Disabled by pain and discomfort Female sex Age at entry into the study doi:10.1371/journal.pone.0098342.t005 Odds Ratio z-Score p-value 95% confidence interval 5.49 3.27 three.39 three.71 0.95 3.49 3.20 2.74 three.94 23.67 ,0.001 0.001 0.006,0.001,0.001 two.1113.30 1.586.76 1.428.10 1.937.14 0.920.98 2.51 2.01 1.95 1.88 0.97 three.08 2.32 2.08 two.11 22.98 0.002 0.020 0.037 0.035 0.003 1.404.52 1.113.63 1.043.68 1.043.37 0.940.98 5 The UPBEAT UK Study- Baseline Findings the prevalence of depression was similar to that found by Egede. The effect of response bias cannot be assessed as 
information on patients not agreeing to participate was not available to us. In the EUROASPIRE study, a prevalence of depression of 18.5% was found in a population of patients recruited in hospitals in the UK at least 6 months after an index cardiac event . However, this study represents a secondary care population and the number recruited into the study from the UK 23977191 was relatively small so comparisons with the primary care population in our study are not very applicable. Comparisons can thus only be tentative. Our total prevalence of depression and anxiety was in keeping with that reported in the basic UK population, but the prevalence rate of depression alone in that study, which also used the CIS-R, was only 2.6%. Gi.Lue 0.003,0.001 0.003,0.001 0.002 0.002,0.001 95% self-assurance interval 1.568.09 1.857.17 1.476.11 two.267.54 1.445.47 1.364.16 3.8319.90 391 101 237 425 3.23 two.66 5.96 five.96 ,0.001 0.003,0.001,0.001 1.726.04 1.395.09 3.2810.83 three.2810.83 289 180 284 1 four.64 7.48 0.010,0.001 1.4514.79 2.5821.68 the basic population in other studies. Salokangas & Poutanen reported that risk factors for depression in the general population were physical health problems, physical disability, and poor social support. Brown & Harris previously reported the association between social problems and the onset of depression. These associations were recognized by GPs, practice nurses and patients participating in qualitative studies as part of the UPBEAT-UK programme. However a novel finding, reflecting the nature of this population was that reporting still experiencing chest pain was one of the strongest associations with depression independent of associations with other pains and discomfort. The chest pain could be due to the underlying ischaemic heart disease or be a somatic symptom associated with the concurrent depression or perhaps both. Further analyses of our data will elucidate this. The prevalence of depressive disorder was lower than previously reported in one US study of people with CHD living in the community. Egede found a prevalence rate of depression in people with CHD of 15%. Possible explanations for the lower prevalence 
of depression in our study is response bias – patients with co-morbid depression or anxiety may be less likely to respond to the GP’s letter inviting participation in the study leading to an underestimation of the prevalence rate, but is also likely to represent the sensitivity of instruments used to detect depression. In our study we used the CIS-R as a `gold-standard’ as this generates ICD-10 diagnoses rather than the probability of depression based on symptom scores. When the HADS was used Variable CIS-R diagnosis of depression Problems living alone Experiences chest pain Disabled by pain and discomfort Problems carrying out usual activities Age at entry into the study GP case note diagnosis of depression Problems with close relationships Diabetes Mellitus Disabled by pain and discomfort Female sex Age at entry into the study doi:10.1371/journal.pone.0098342.t005 Odds Ratio z-Score p-value 95% confidence interval five.49 3.27 3.39 three.71 0.95 3.49 three.20 2.74 3.94 23.67 ,0.001 0.001 0.006,0.001,0.001 2.1113.30 1.586.76 1.428.10 1.937.14 0.920.98 2.51 two.01 1.95 1.88 0.97 3.08 2.32 two.08 two.11 22.98 0.002 0.020 0.037 0.035 0.003 1.404.52 1.113.63 1.043.68 1.043.37 0.940.98 5 The UPBEAT UK Study- Baseline Findings the prevalence of depression was similar to that found by Egede. The effect of response bias cannot be assessed as information on patients not agreeing to participate was not available to us. In the EUROASPIRE study, a prevalence of depression of 18.5% was found in a population of patients recruited in hospitals in the UK at least 6 months after an index cardiac event . However, this study represents a secondary care population and the number recruited into the study from the UK 23977191 was relatively small so comparisons with the primary care population in our study are not very applicable. Comparisons can thus only be tentative. Our total prevalence of depression and anxiety was in keeping with that reported in the common UK population, but the prevalence rate of depression alone in that study, which also used the CIS-R, was only two.6%. Gi.