Abstract
BackgroundDepression guidelines in the UK recommended a policy of watchful waiting for mild depression due to a lack of evidence for the effectiveness of antidepressant treatment for mild cases. However there has been relatively little research carried out in primary care to help establish the severity threshold at which antidepressant treatment is effective and cost-effective.Methods/DesignThe THREAD (THREshold for AntiDepressants) study is a multi-centre randomised controlled trial designed to determine the clinical and cost effectiveness of a selective serotonin reuptake inhibitor (SSRI) plus general practitioner (GP) supportive care, versus supportive care alone, for mild to moderate depression in primary care. The aim is to recruit 300 patients from three centres (Southampton, London and Liverpool). Depressive symptoms will be assessed at baseline, 12 weeks and 26 weeks, using the 17-item Hamilton Depression Rating Scale (HDRS). Two severity sub-groups of patients will be recruited, with HDRS scores of 12–15, and 16–19. Possible predictors of response will be explored including life events and difficulties and alcohol consumption. Analysis of covariance, controlling for baseline value, severity group and centre will be used to estimate the overall treatment effectiveness (difference in HDRS score) at final follow up. The primary analysis will be by 'intention to treat' using double sided tests. The interaction between severity sub-group and treatment will be tested, and if appropriate, effects within separate severity sub-groups estimated. The economic analysis will compare the two treatment groups in terms of mean costs and cost-effectiveness.DiscussionThe results of this study will give GPs important information to help them determine the severity of depression at which antidepressant treatment is likely to be cost-effective.
Highlights
Depression guidelines in the UK recommended a policy of watchful waiting for mild depression due to a lack of evidence for the effectiveness of antidepressant treatment for mild cases
Increasing prescribing of antidepressants – is it appropriate? Prescribing of antidepressant drugs has increased by 36% over the last 5 years to around 30 million items (7.3 million in the quarter to June 2005), and the cost has increased by 20% to around £380 million (£91 million for the same quarter) [1]
Antidepressants are not recommended for the initial treatment of mild depression because the risk-benefit ratio is considered to be poor
Summary
Increasing prescribing of antidepressants – is it appropriate? Prescribing of antidepressant drugs has increased by 36% over the last 5 years to around 30 million items (7.3 million in the quarter to June 2005), and the cost has increased by 20% to around £380 million (£91 million for the same quarter) [1]. Studies in primary care have shown that antidepressants are more effective than placebo or treatment as usual for probable major depression but results have been mixed for minor (mild) depression. Previous research in primary care A general practice based placebo-controlled trial of amitriptyline found that patients with probable major depressive disorder benefited from drug treatment, but those with minor depression did no better on them than on placebo [5]. These findings represent a posthoc analysis of responses in the two sub-groups of patients who did or did not fulfil criteria for a diagnosis of probable major depression. If it is more effective, does this apply across the whole range of severity of symptoms of mild to moderate depression?
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