The study, published in the British Medical Journal (BMJ), and funded by NIHR School for Primary Care Research (NIHR SPCR), found that compared with selective serotonin reuptake inhibitor (SSRI) treatments, rates of suicide and self-harm were significantly higher in patients taking other commonly prescribed types of antidepressants, including venlafaxine, trazodone and mirtazapine.
The research led by Dr Carol Coupland, associate professor and reader in medical statistics in the University’s Division of Primary Care also found that rates of suicide and self-harm were highest in the first 28 days after starting antidepressants and remained increased in the first 28 days after stopping treatment.
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Influencing factors
Dr Coupland said: “Our study found that rates of suicide and self-harm were similar for patients prescribed SSRIs and tricyclic and related antidepressants, but were higher for some other types of antidepressants. However, these results may have been influenced by other factors including the severity of depression. It is also important to be mindful that the number of suicides and instances of attempted suicide and self-harm among patients were still relatively low.
“The results of our study indicate that more research into these potential links is warranted, but do suggest that the benefits and risks of different antidepressant treatments should be considered when antidepressants are prescribed and also that GPs should monitor patients carefully in the first four weeks of starting and stopping antidepressant treatment.”
Depression is a common condition, affecting around five per cent of the population of the UK. Rates of suicide and self-harm are greatly increased in people with depression and the reduction of these risks is a major consideration when treating patients with depression. Paradoxically, although antidepressants have been shown to be effective in reducing symptoms of depression, there is concern that the rates of suicide and self-harm may actually be increased by antidepressant use, particularly in younger people.
Results
The study looked at 238,963 patients, aged 20 to 64 years and registered with UK GPs contributing data to the QResearch database, from first diagnosis of depression between January 2000 and July 2011 inclusive and followed through until August 2012.
The results showed that during follow up 87.7 per cent of patients received one or more prescriptions for antidepressants, with a median treatment length of 221 days.
During the first five years of follow up, the researchers found that there were 198 cases of suicide and 5,243 cases of attempted suicide or self-harm.
Compared with the commonly used SSRI antidepressants, there was no significant difference in the rate of suicide or self-harm for tricyclic and related antidepressants, one of the oldest classes of antidepressants which were commonly used before the introduction of SSRIs, but rates were significantly higher for treatment with other antidepressants.
Potential risks
When compared with the commonly used SSRI antidepressant citalopram, the suicide rate was significantly higher during periods of treatment with mirtazapine, and rates of self-harm were significantly increased during treatment with venlafaxine, trazodone and mirtazapine. The absolute risks of suicide over one year ranged from a 0.02 per cent risk for amitriptyline to a 0.19 per cent risk for mirtazapine. Absolute risks of attempted suicide or self-harm over one year ranged from a one per cent risk for amitriptyline to almost three per cent for patients taking venlafaxine.
Professor Julia Hippisley-Cox, who is a co-author on the research paper and a GP, said: “These increases, although significant, are still relatively small and need further research before we can provide a definitive answer on the potential risks involved with these medications.
“While some patients currently taking these drugs may find these results concerning, stopping these medications without seeking medical advice could be dangerous. Anyone with any concerns should discuss them with their GP at their next appointment.”
The full paper is available on the BMJ website:
www.bmj.com/content/350/bmj.h51