Depression should be managed like a chronic disease

Depression is often referred to as the common cold of psychiatry. But this analogy is wrong: although common, most depressive disorders are not mild and self limiting. It is time that we treated depression as the chronic disease that it is.

The World Bank ranks unipolar depression as the number one contributor to the global burden of disease in adults aged 19-45 in the developed world.1 Up to 15% of adults may experience clinical depression, 20% will not recover fully from the index episode, and 70-80% of those achieving remission succumb to at least one recurrence. Eighty per cent of individuals with milder persistent symptoms or dysthymia will develop a major depressive episode, and 15% of all patients with depression will eventually commit suicide.

Ninety per cent of cases of depression are treated in primary care, where depression is the third most common reason for consultation. Two articles in this issue hypothesise that screening for depression cases would not improve patient outcomes (p 1027),2 whereas increased access to therapy would (p 1030).3 The truth probably lies somewhere in between. So what should primary care offer to individuals with depression?

The two most important barriers to effective depression management are under-recognition (30% remain undetected) and undertreatment (> 50% are untreated).4 Gilbody et al's paper2 and their previous Cochrane review5 suggest that screening is unlikely to improve short term outcomes (6-12 months) or be cost effective so it does not meet enough of the National Screening Committee's criteria to warrant introduction. However, universal screening as an isolated intervention, divorced from a coherent plan of how to manage detected cases, is neither supported by the National Screening Committee nor likely to be advocated by healthcare providers for any disorder. Screening for depression, as for diabetes, is of value only when the rationale for enhancing case recognition is clear, the programme targeted at high risk populations, and the strategy linked to a systematic approach not only to acute treatment but also to tertiary prevention.6

The value of “chronic disease management” has been shown in other disorders such as asthma and hypertension, so templates exist to develop a similar shared care approach to depressive disorders with appropriate, achievable primary care targets. Short term health economic benefits may not materialise, as cost effectiveness will not only depend on detecting and treating individual depressive episodes but also on reducing recurrences and persistent subsyndromal symptoms.

We need a paradigm shift to recognise that depression is a life course disorder. The piecemeal approach to treatment, which has too often focused on the ad hoc management of isolated acute episodes, could then be replaced with a systematic sequence of acute, continuation, and maintenance phase interventions.7 The difficulties of implementing this strategy are the continuing problem of undertreatment and the potential resource implications for primary care teams already stretched by other pressures.

Undertreatment results mainly from doctors failing to prescribe effectively and from patients failing to take their drugs. Failure of prescribing is disappointing as the diagnostic criteria for depressive episodes requiring clinical intervention are more transparent than for many physical conditions.7 8 When treatment is provided in an adequate dose for an adequate period improvement rates are at least 60% by 12-16 weeks; when medication is continued beyond the acute phase relapse rates are reduced by 50% compared with those in patients who stop taking antidepressants.7 These outcomes exceed the treatment gains achieved for many common physical disorders.8

A barrier to effective treatment seems to be clinicians' perceptions of depression: the onset of an episode is often understandable in the context of life stressors or known personality vulnerabilities, but “normalising” the experience should not exempt it from treatment. Many clinicians and patient advocates argue that patients are often ambivalent about or opposed to antidepressants and often don't take them.9 Increased access to treatment would be beneficial if it focused on the provision of evidence based interventions with a durable effect on an individual's pattern of coping, so reducing their risk of relapse after treatment has stopped. There is no evidence that this can be achieved by the recent increase in access to non-specific counselling.10 Layard's proposal for increased availability of cognitive behaviour therapy may help, but cognitive behaviour therapy is not a panacea: dropout rates (30%) are similar to those for medication and there is no clinical characteristic that allows us to predict which patients will respond best to cognitive behaviour therapy and which to antidepressants.11

Would greater case finding and evidence based treatment divert resources away from those with “greater need and ability to benefit”? This argument seems unsustainable. Depression is top of the list of the global burden of disease, and the statistics on recurrence, chronicity, and lost human capital speak for themselves. Depressive disorders are also associated with an increased risk of many highly morbid physical disorders including metabolic syndromes.12 Studies from the United States and Europe indicate that those with untreated depression attend primary care significantly more often than other patients.13 Modifying perceptions of the disorder and changing the interventions made during consultations may be more critical than assuming that extra consultations are the only alternative.

Should additional funding be made available? If resources were allocated on the basis of the burden caused by a disease, the prospects would be improved for financial backing to implement better treatment options for depression. But funding issues should not be an excuse for inactivity: the lack of joined up thinking about this much misunderstood disorder seems to be the rate limiting step.