Depression is common and disabling. The estimated point prevalence for major depression among 16 to 65 year olds in the United Kingdom (UK) is 21/1000 (males 17, females 25). Mixed anxiety and depression is prevalent in a further 10 percent of adult patients attending general practice (National Institute of Health and Clinical Excellence [NICE] Depression guideline, 2004). It contributes 12 percent of the total burden of non-fatal global disease and by 2020, looks set to be second after cardiovascular disease in terms of the world's disabling diseases (Murray CJL and Lopez AD, 1996). Major depressive disorder is increasingly seen as chronic and relapsing, resulting in high levels of personal disability, lost quality of life for patients, their family and carers, multiple morbidity, suicide, higher levels of service use and many associated economic costs. In 2000, 109.7 million lost working days and 2,615 deaths were attributable to depression. The total annual cost of adult depression in England has been estimated at over 9 billion pounds, of which 370 million pounds represents direct treatment costs.
This measure is one of two Depression measures.
Depression is more common in people with coronary heart disease (CHD) and presence of depression is associated with poorer outcomes. Up to 33 percent of patients develop depression after a myocardial infarction (MI) (Davies et al., BMJ 2004).
The presence of depression in people with coronary heart disease is associated with reduced compliance with treatment, increased use of health resources, increased social isolation, and poorer outcomes (Carney et al., American Journal of Cardiology 2003).
A meta-analysis of 20 trials (Barth et al., Psychosomatic Medicine 2004) found that depressive symptoms and clinical depression in people with CHD increased mortality for all follow up periods even after adjustment for other risk factors. In other words, depression was an independent risk factor for mortality in people with CHD. There is Grade A evidence from two randomised controlled trials that selective serotonin reuptake inhibitor (SSRI) antidepressant treatment in people with coronary heart disease is safe and effective in reducing depression, at least among those with a prior history of depression and more severe symptoms (Glassman et al., Journal of the American Medical Association 2002; Taylor et al., Archives of General Psychiatry 2005). Patients treated with an SSRI were also found to have a 42% reduction in death or recurrent MI in a sub-group analysis of outcomes in a trial of cognitive behavioural therapy (CBT), although this was a post-hoc observation, and assignment to antidepressants was not randomised (Lesperance et al., Journal of the American Medical Association 2007).
There is a 24 percent lifetime prevalence of co-morbid depression in individuals with diabetes mellitus (Goldney et al., Diabetes Care 2004), a prevalence rate three times higher than the general population. A recent meta-analysis of 42 studies found that depression is clinically relevant in nearly one in three patients with diabetes (Anderson et al., Diabetes Care 2001). People with both diabetes and depression are less physically and socially active (Von Korf et al., Psychsomatic Medicine 2005) and less likely to comply with diet and treatment than people with diabetes alone, leading to worse long term complications and higher mortality. It may also be that practitioners provide poorer care to patients with co-morbid depression and diabetes because depression impairs communication with patients (Piette et al., American Journal of Managed Care 2004). There is Grade A evidence from five randomised controlled trials that effective treatment with either antidepressants or CBT improves the outcome of depression in patients with diabetes
(Lustman et al., Psychosomatic Medicine 1997; Lustman et al., Annals of Internal Medicine 1998; Lustman et al., Diabetes Care 2000; Katon et al., Archives of General Psychiatry 2004; Williams et al., Annals of Internal Medicine 2004). While treatment has not been shown consistently to improve glycaemic control, psychological well-being has been identified as an important goal of diabetes management in its own right by the St Vincent Declaration.
NICE guidance on Depression suggests that "screening should be undertaken in primary care ...for depression in high-risk groups" (Grade C) and that "screening for depression should include the use of at least two questions concerning mood and interest:
- During the last month, have you often been bothered by feeling down, depressed or hopeless?
And
- During the last month, have you often been bothered by having little interest or pleasure in doing things?"
(NICE Grade B)
A "yes" answer to either question is considered a positive test. A "no" response to both questions makes depression highly unlikely. These two brief questions could be asked as part of a diabetes or coronary heart disease review and patients who answer "yes" to either questions could be referred to the general practitioner (GP) for further assessment of other symptoms such as tiredness, guilt, poor concentration, change in sleep pattern and appetite and suicidal ideation to confirm a diagnosis of depression. This assessment should be informed by using a questionnaire measure of severity such as the nine item Patient Health Questionnaire (PHQ-9), Hospital Anxiety and Depression Scale (HADS), or Beck Depression Inventory (BDI), as used for the associated depression indicator referenced above (see also Whooley et al., Journal of General Internal Medicine 1997; Arroll et al., BMJ 2003).
The specificity of screening has been shown to be improved by the addition of a third 'help' question asked of patients answering 'yes' to either of the first two questions: Is this something with which you would like help? (Arroll et al. British Medical Journal 2005) This third question has three possible responses: 'no', 'yes, but not today', or 'yes'. A 'no' response to this third question makes major depression highly unlikely (negative predictive value [NPV] of 94%). It is important to stress therefore that a negative result to the two to three item screen can usually be taken to indicate that the patient doesn't have depression.
