There is no proof that 85% of the depression apps currently recommended by the NHS for patients to manage their condition actually work, say experts in the journal Evidence Based Mental Health.

But the seal of approval from one of the world's leading healthcare systems may falsely reassure patients, many of whom are increasingly opting to fund their own treatment in the face of overstretched mental health services and the associated lengthy waits, they warn.

Until such time as evidence is forthcoming on the clinical effectiveness of these apps, and they have been properly evaluated, they should be removed from the NHS apps library, say Simon Leigh and Steve Flatt, of, respectively, the Management School at the University of Liverpool, and Liverpool Psychological Therapies Unit Community Interest Company.

One in 10 patients with mental health issues in England is now waiting more than a year before getting any form of treatment, and one in two waits more than three months.

One in six of those waiting for treatment is expected to attempt suicide, while four in 10 is expected to self-harm. And their condition is likely to worsen in two thirds of those waiting to see a mental health professional.

Interactive online and app based treatments for mental health are becoming increasingly popular and accessible as a result of the growth in routine use of smartphones and tablets. As such, they may be just what the cash-strapped NHS is looking for, say the authors.

But these options need to be "well informed, scientifically credible, peer reviewed and evidence based" and, importantly, their performance needs to be measured against a validated set of performance criteria, they insist.

But in 2013, there were only 32 published articles on apps for depression, one of the most common mental health conditions, despite the availability of more than 1500 for download, they point out.

The same is true of apps for a range of other mental health issues, including bipolar disorder, bulimia, and post-traumatic stress disorder, which suggests that they don't meet these standards, the authors say.

"Unfortunately, the situation seems to be much the same with respect to apps accredited by the NHS," they write.

Of the 27 mental health apps currently listed in the NHS library, 14 are for depression and anxiety. Yet only four provide any scientific proof that they work when used by patients, and only two of them have been properly evaluated for clinical effectiveness.

"As such, confidence in, and the validity of, the claims made by apps that fail to apply such metrics must be considered as low at best, suggesting that the true clinical value of over 85% of NHS accredited mental health apps is at present impossible to determine," state the authors.

And there is a perceived level of quality assurance that comes with accreditation by the NHS, they point out. But just like information sources on the internet, the quality of apps varies.

"Given that 3 in 10 individuals with an untreated mental health issue now opt to pay for private treatment on account of limited NHS availability, the purchase and use of apps that are yet to demonstrate objective clinical benefit is not only a potential waste of money, but also likely to have compounding effect on levels of anxiety in those with the greatest need and least access to effective treatment," they warn.

"In order to ensure that apps don't do more harm than good, it is important that those presently recommended by the NHS apps library that either fail to demonstrate the evidence underlying the methodological approach taken, or evidence of effectiveness in use, are removed," they conclude.

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