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Concerns raised over side effects of newer antidepressants

SSRIs are not necessarily safest for older people, warns study

Adrian O'Dowd

Wednesday, 03 August 2011

Newer generation antidepressants – selective serotonin reuptake inhibitors (SSRIs) – are linked to an increased risk of several severe adverse outcomes in older people, finds a study published online today by the BMJ. 

The higher risk compared with older tricyclic antidepressants (TCAs) are stressed in the study by a team of UK researchers. 

GPs should now carefully evaluate the risks and benefits of different antidepressants when prescribing these drugs to older people. Antidepressants, particularly SSRIs, are widely used to treat depression in older people, but little is known about the safety of these drugs when used in this part of the population. 

A team of researchers at the Universities of Nottingham and East Anglia set out to investigate the association between antidepressant treatment and the risk of a number of potentially life threatening outcomes in older people. 

For the study, they identified 60,746 UK patients aged 65 and over with a newly diagnosed episode of depression between 1996 and 2007. Many patients had other conditions, such as heart disease and diabetes, and were taking several medications. 

Patients were tracked until the end of 2008 and during this time, 54,038 (89%) received at least one prescription for an antidepressant. Of these prescriptions, 55% were for SSRIs, 32% for TCAs, 0.2% for monoamine oxidase inhibitors (MAOIs), and the rest were for other antidepressants.

The researchers analysed antidepressant use by looking at several adverse outcomes such as all-cause mortality, attempted suicide or self harm, heart attack, stroke, falls, fractures, epilepsy or seizures, and hyponatraemia. 

After adjusting for factors that could affect the results, including age, sex, severity of depression, other illnesses and use of other medications, the team found that SSRIs and drugs in the group of other antidepressants were associated with an increased risk of several adverse outcomes compared with TCAs. 

They found that depressed patients who were not taking antidepressants at all had a 7% risk of dying some time in the next year, while the comparable risks were 8.1% for those taking TCAs, 10.6% for SSRIs, and 11.4 % for the group of other antidepressants. For stroke, one-year risks were 2.3%, 2.6% and 3% (compared to 2.2% for those not on antidepressants) respectively, and for fracture they were 2.2%, 2.7% and 2.8% compared to 1.8%. 

The authors acknowledged that TCAs were prescribed at lower doses than SSRIs and other antidepressant drugs, which they say “could in part explain our findings”. They also warned that differences between patients prescribed different antidepressant drugs may account for some of the associations seen in the study and suggest that further research was needed to confirm the findings. 

However, they said: “The risks and benefits of different antidepressants should be carefully evaluated when these drugs are prescribed to older people.” 

In an accompanying editorial, Professor Ian Hickie from the University of Sydney, Australia, said, despite some limitations, “the study has clear implications for more informed prescribing and enhanced clinical monitoring”.

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