Multimorbidity and the risk of depression in different ethnic groups

The problem

Around a third of patients seen in primary care have two or more long-term conditions (LTCs) known as multimorbidity (MM). The prevalence of MM is increasing and is associated with a poor quality of life and increased incidence of depression.Depression affects 1 in 5 of the UK population and is associated with high rates of healthcare utilisation and cost. Bhattarai et al (2013) found that the prevalence of depression was higher in patients with greater numbers of LTCs. However this study was limited by the number of long-term conditions included and did not adjust for ethnicity. Previous studies have demonstrated lower rates of depression in ethnic minority populations.Our aim was to investigate the relationship between depression and MM in the different ethnic populations.

The approach

We extracted annonymised patient level data from two large primary care databases, the East London database and Lambeth DataNet. This yielded over 900,000 patients aged over 18 years, registered at GP practices in four ethnically diverse London boroughs. We constructed regression models in order to identify the predictors of depression. We included 13 QOF conditions in the analysis and calculated the odds ratio (OR) for depression depending on the number of LTCs. We stratified the population by ethnicity (White, Black and South Asian), repeating the analysis for each ethnic group, adjusted for age and gender.

Findings

Patients with just one LTC were more likely to be recorded with depression than those without a LTC, OR=1.79 (95%CI 1.76, 1.82); for those with five or more LTCs, OR=1.95 (95%CI 1.79, 2.13). For each additional LTC the risk of depression increased, OR=1.26 (95%CI 1.25, 1.27).The likelihood of depression was higher with MM compared to no MM in each ethnic group. The OR for depression with one LTC was significantly lower in the White population, OR=1.77 (95%CI 1.73, 1.81) compared to the South Asian population OR=2.05 (95%CI 1.96, 2.14) and this pattern remained with increasing MM:with 5 or more LTCs the OR in the White population was 1.71 (95%CI 1.53, 1.91) and in the South Asian population was 2.57 (95%CI 2.08, 3.17).Values for the black population with MM were intermediate between the White and South Asian populations.Consequence: The likelihood of depression increased by 79% in the presence of one LTC and almost doubled in those with five or more LTCs.Despite lower overall likelihood of depression in the ethnic minority populations, when the effect of MM was analysed, this relationship changed with the likelihood of depression becoming higher in ethnic minorities with MM compared to the white population with MM.We have presented preliminary results. Further analysis comparing depression rates and MM, adjusted for social deprivation, will be required before drawing firm conclusions.

Credits

• Chandra Sarkar
• Alexander Gilkes
• Mark Ashworth