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Right to a fair trial: St John’s wort

29 Oct, 09 | by Steven Reid, Evidence-Based Mental Health

The updated NICE guideline for depression is just out. Here is what it has to say about St John’s wort:

Although there is evidence that St John’s wort may be of benefit in mild or moderate depression, practitioners should:
• not prescribe or advise its use by people with depression because of uncertainty about appropriate doses, persistence of effect, variation in the nature of preparations and potential serious interactions with other drugs (including oral contraceptives, anticoagulants and anticonvulsants)
• advise people with depression of the different potencies of the preparations available and of the potential serious interactions of St John’s wort with other drugs.

Funny that. In the last issue of EBMH, Edzard Ernst, the professor of complementary medicine who has become the bête noire of the alternative medicine crowd was less dismissive. Reviewing the latest Cochrane update he concludes that there is now plenty of evidence demonstrating that SJW is an effective antidepressant and if you can avoid herb-drug interactions, it may be safer than conventional drugs. So why don’t we recommend SJW for depression?

I have written about SJW here before and was less than complimentary (ouch!). My scepticism was similar to the NICE position: you can’t be sure what you are getting, and patients thinking that it’s not really a drug mix it with prescription medication and run into trouble. Perhaps, however, there is more to it than that. Given the rather murky history of clinical trials and marketing with conventional antidepressants and the often marginal benefit over placebo it does seem as though when it comes to evidence we hold St John’s wort to a higher standard. Trawl through the rapid responses of a trial involving SJW and you will find a degree of nit-picking that is rarely seen with the SSRIs. This type of reader or reviewer bias is not much discussed and competing interest statements rarely include declarations of inherent prejudice. In this editorial for Clinical Evidence, Professor Ernst criticises the knee-jerk assumption that if a clinical trial of a complementary medicine shows efficacy it must be a flawed trial. So is St John’s wort being treated unfairly? The answer, I think, has to be yes.

St John’s wort works for depression…in Germany

13 Oct, 08 | by Steven Reid, Evidence-Based Mental Health

The benefits of St John’s wort (SJW) have been widely reported this week following the publication of this study. It’s not, as some articles suggest, a new trial but actually an update of a Cochrane systematic review and meta-analysis. The review is comprehensive, with the addition of some big recent RCTs, and the authors have restricted the inclusion criteria to major depression. The results reinforce those of earlier reviews: SJW is as effective as standard antidepressants in mild and moderate depression with the benefit of fewer side effects.

Perhaps the most interesting finding is that studies from German-speaking countries show much more favourable results. In fact taking out the German studies from the meta-analysis removes any benefit of SJW over placebo. It’s not easy to explain this difference – you can insert your own cultural jokes here. What is notable is that the German trials predominantly recruited from private practices in primary care with a long tradition of prescribing SJW. This contrasts with the remainder where studies were carried out in academic or hospital settings where SJW is not licensed as a drug. Despite matching inclusion criteria there may have been differences between the types of patient entering the trials (selection bias). Andere Länder, andere Sitten.

So given this ‘natural’ alternative why don’t I recommend SJW to people I see with depression? Well in the UK it’s not licensed as a medicine but sold as a dietary supplement, and comes over the counter in a variety of formulations: pills, potions, lotions – you might even to able to smoke it. That means it can be difficult to know what you are getting and dosages in this review varied from 240 to 1800 mg per day. The active ingredient and mechanism of action is still unknown – not that we really understand how standard antidepressants work either. The other concern is the potential for drug interactions. SJW stimulates those liver enzymes that break down medicines such as warfarin, HIV drugs and oral contraceptives rendering them ineffective. Combining it with other antidepressants can also have nasty effects: I had a near miss with a woman starting on the antidepressant sertraline, who hadn’t admitted to SJW use as it was a ‘herb’ she was taking for migraine. So it may be a plant extract but it is certainly not innocuous.

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