Depression has a poor prognosis, recovery is slow and relapse is common, a primary care study from Finland has found.

The Vantaa Primary Care Depression Study screened patients for depression using the PRIME-MD questionnaire. Those with a positive result were invited to attend a DSM-IV structured clinical interview.

A total of 137 patients with DSM IV depressive disorder were recruited and followed up for five years.

Overall, 82% of the participants completed the study. Of these, 102 patients had a baseline diagnosis of major depression or subsyndromal depression (2-4 depressive symptoms with a previous history of major depression).

Information from diagnostic interviews, rating scales and medical records was used to create life-charts in which the follow-up time was divided into three categories:full remission, partial remission (1-4 depressive symptoms) and major depression (≥ 5 symptoms).

Although 70% of the patients (71/102) achieved full remission, this was a slow process, with a median time to remission of 20 months, and one third of them had at least one recurrence.

Overall, the patients spent:

• 42% of the follow-up time in full remission (2.1 years)

• 24% of the time in partial remission (1.2 years)

• 34% of the time in major depressive episodes (1.7 years)

The main predictor of outcome was the severity of depression at baseline. Comorbid substance use was also associated with poor outcomes.

This was a naturalistic study and provides further evidence that in real life (as opposed to research settings) the prognosis for depression is poor.

Previous studies have suggested a poor prognosis in the medium term, with 12-month recovery rates between 32% and 67% .¹The present study suggests that the long-term prognosis is also poor: less than half the patients were in full remission after five years.

There are a number of reasons for poor outcomes in depression.

Patients, particularly those identified by screening, may be reluctant to accept treatment. Most of those who accept treatment will not respond fully² and there may then be a failure to adjust their treatment.

Of those who do respond, many will stop their treatment prematurely: antidepressants should be continued for at least six months after remission, extending to at least two years for those at high risk of relapse.³

It has been suggested that depression should be managed as a chronic disease.⁴ However, telling patients that the prognosis is poor, and that their depression is likely to be chronic and recurrent, is unlikely to improve outcomes.

The key point is that poor outcomes in naturalistic studies reflect the fact that most patients with depression do not receive effective treatment.

We can be more optimistic about the outcome providing that patients understand the importance of adherence, active follow-up, treatment adjustment when necessary, and relapse prevention.

Dr Phillip Bland