a1 Department of Primary Care and Public Health Sciences, King's College London, UK
a2 Department of Social Policy, London School of Economics and Political Science, UK
Background This study aimed to determine whether depression in patients with long-term conditions is associated with the number of morbidities or the type of co-morbidity.
Method A cohort study of 299 912 participants aged 30–100 years. The prevalence of depression, rates of health-care utilization and costs were evaluated in relation to diagnoses of diabetes mellitus (DM), coronary heart disease (CHD), stroke and colorectal cancer.
Results The age-standardized prevalence of depression was 7% in men and 14% in women with no morbidity. The frequency of depression increased in single morbidities including DM (men 13%, women 22%), CHD (men 15%, women 24%), stroke (men 14%, women 26%) or colorectal cancer (men 10%, women 21%). Participants with concurrent diabetes, CHD and stroke had a very high prevalence of depression (men 23%, women 49%). The relative rate of depression for one morbidity was 1.63 [95% confidence interval (CI) 1.59–1.66], two morbidities 1.96 (95% CI 1.89–2.03) and three morbidities 2.35 (95% CI 2.03–2.59). Compared to those with no morbidity, depression was associated with higher rates of health-care utilization and increased costs at any level of morbidity. In women aged 55 to 64 years without morbidity, the mean annual health-care cost was £513 without depression and £1074 with depression; when three morbidities were present, the cost was £1495 without depression and £2878 with depression.
Conclusions Depression prevalence and health-care costs are more strongly associated with the number of morbidities than the nature of the co-morbid diagnosis.
(Received April 20 2012)
(Revised October 01 2012)
(Accepted October 02 2012)
(Online publication November 01 2012)
c1 Address for correspondence: N. Bhattarai, MPH, MSc, Division of Health and Social Care Research, King's College London, 7th Floor Capital House, 42 Weston Street, London SE1 3QD, UK. (Email: firstname.lastname@example.org)