Most off-label antidepressant prescriptions lack evidence

We’re likely to believe that if our doctor prescribes us a drug, it’s exactly what we need. 

But a new study warns this is hardly the case. 

Most off-label antidepressant prescriptions lack strong scientific evidence, scientists claim.

Off-label use occurs when a drug is prescribed for a different condition, given to a different patient group, such as children, or in a different dose than in the approved label.

And while most assume there is no harm, evidence has shown that off-label drug use without strong evidence is associated with an increased risk of problems such as allergic reactions, and overdoses.

Most off-label antidepressant prescriptions lack strong scientific evidence, a new study claims

Antidepressant use has increased substantially in countries such as the US, the UK and Canada. 

In England, the number of antidepressants dispensed increased by 3.9 million (6.8 percent) between 2014 and 2015 – more than any other class of prescription drugs.

And in the US, more than 41 million Americans – one out of eight – are taking at least one antidepressant.

But approximately one-third of antidepressants are prescribed for ‘off-label’ conditions, with pain, insomnia and migraine being the most common.

However, it is unknown to what extent these prescriptions are supported by scientific evidence.

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A team of researchers decided to examine off-label indications for antidepressants in primary care and assess their level of scientific support.

Using data from an electronic prescribing system, they looked at over 100,000 antidepressant prescriptions written by almost 200 primary care physicians between January 2003 and September 2015 in Quebec, Canada.  

The researchers found that almost 30 percent of all antidepressant prescriptions were written for an off-label condition.

Tricyclic antidepressants (TCAs) had the highest prevalence, while selective serotonin reuptake inhibitors (SSRIs) and serotonin-noradrenaline reuptake inhibitors (SNRIs) were less likely to be prescribed off-label.

Among all off-label antidepressant prescriptions, only 16 percent had strong scientific evidence backing the drug’s use for the indication, with a further 40 percent lacking any strong evidence.

However, there was strong evidence for another drug in the same class.

For the remaining 44 percent of off-label prescriptions, neither the prescribed drug nor any other drugs in the class had scientific support for the indication.

The researchers said there were several reasons why physicians would prescribe antidepressants for off-label use.

This included difficulties keeping track of new indications for specific products, constraints on drug insurance plans, and perceptions that alternative treatment options may carry more risks than taking antidepressants.

They said the results ‘highlight an urgent need to produce more evidence on the risks and benefits of off-label antidepressant use and to provide physicians with this evidence at the point of prescribing.’

And they concluded that technologies such as indication based e-prescribing systems and electronic health records, combined with knowledge databases, could also provide an effective means for communicating evidence back to doctors to improve prescribing decisions.

In a linked editorial, researchers at the University of Dundee argued that the strength of evidence matters more than the presence or absence of a specific licence.

‘Off-label prescribing matters because it is usually (but not always) associated with substantial uncertainty about the balance of benefit and harm,’ Dr Daniel Morales and Professor Bruce Guthrie wrote.

‘Prescribers should therefore be cautious when they prescribe an off-label medicine on the basis of an extrapolation of evidence for a different indication.’ 

But they point out that these pitfalls are not confined to off-label drugs. 

‘For all prescribing, patients (or their parents or carers) should be given enough information to allow them to make an informed decision whether to take a medicine,’ they continued.

‘This should include whether the intended use is off-label, but more importantly prescribers should discuss the strength of the evidence base underlying their recommendation.’