Alternative therapies for psoriasis? A poor review in a top journal

Psoriasis is one of those conditions that is

• chronic,
• not curable,
• irritating to the point where it reduces quality of life.

In other words, it is a disease for which virtually all alternative treatments on the planet are claimed to be effective. But which therapies do demonstrably alleviate the symptoms?

This review (published in JAMA Dermatology) compiled the evidence on the efficacy of the most studied complementary and alternative medicine (CAM) modalities for treatment of patients with plaque psoriasis and discusses those therapies with the most robust available evidence.

PubMed, Embase, and ClinicalTrials.gov searches (1950-2017) were used to identify all documented CAM psoriasis interventions in the literature. The criteria were further refined to focus on those treatments identified in the first step that had the highest level of evidence for plaque psoriasis with more than one randomized clinical trial (RCT) supporting their use. This excluded therapies lacking RCT data or showing consistent inefficacy.

A total of 457 articles were found, of which 107 articles were retrieved for closer examination. Of those articles, 54 were excluded because the CAM therapy did not have more than 1 RCT on the subject or showed consistent lack of efficacy. An additional 7 articles were found using references of the included studies, resulting in a total of 44 RCTs (17 double-blind, 13 single-blind, and 14 nonblind), 10 uncontrolled trials, 2 open-label nonrandomized controlled trials, 1 prospective controlled trial, and 3 meta-analyses.

Compared with placebo, application of topical indigo naturalis, studied in 5 RCTs with 215 participants, showed significant improvements in the treatment of psoriasis. Treatment with curcumin, examined in 3 RCTs (with a total of 118 participants), 1 nonrandomized controlled study, and 1 uncontrolled study, conferred statistically and clinically significant improvements in psoriasis plaques. Fish oil treatment was evaluated in 20 studies (12 RCTs, 1 open-label nonrandomized controlled trial, and 7 uncontrolled studies); most of the RCTs showed no significant improvement in psoriasis, whereas most of the uncontrolled studies showed benefit when fish oil was used daily. Meditation and guided imagery therapies were studied in 3 single-blind RCTs (with a total of 112 patients) and showed modest efficacy in treatment of psoriasis. One meta-analysis of 13 RCTs examined the association of acupuncture with improvement in psoriasis and showed significant improvement with acupuncture compared with placebo.

The authors concluded that CAM therapies with the most robust evidence of efficacy for treatment of psoriasis are indigo naturalis, curcumin, dietary modification, fish oil, meditation, and acupuncture. This review will aid practitioners in advising patients seeking unconventional approaches for treatment of psoriasis.

I am sorry to say so, but this review smells fishy! And not just because of the fish oil. But the fish oil data are a good case in point: the authors found 12 RCTs of fish oil. These details are provided by the review authors in relation to oral fish oil trials: Two double-blind RCTs (one of which evaluated EPA, 1.8g, and DHA, 1.2g, consumed daily for 12 weeks, and the other evaluated EPA, 3.6g, and DHA, 2.4g, consumed daily for 15 weeks) found evidence supporting the use of oral fish oil. One open-label RCT and 1 open-label non-randomized controlled trial also showed statistically significant benefit. Seven other RCTs found lack of efficacy for daily EPA (216mgto5.4g)or DHA (132mgto3.6g) treatment. The remainder of the data supporting efficacy of oral fish oil treatment were based on uncontrolled trials, of which 6 of the 7 studies found significant benefit of oral fish oil. This seems to support their conclusion. However, the authors also state that fish oil was not shown to be effective at several examined doses and duration. Confused? Yes, me too!

Even more confusing is their failure to mention a single trial of Mahonia aquifolium. A 2013 meta-analysis published in the British Journal of Dermatology included 5 RCTs of Mahonia aquifolium which, according to these authors, provided ‘limited support’ for its effectiveness. How could they miss that?

More importantly, how could the reviewers miss to conduct a proper evaluation of the quality of the studies they included in their review (even in their abstract, they twice speak of ‘robust evidence’ – but how can they without assessing its robustness? [quantity is not remotely the same as quality!!!]). Without a transparent evaluation of the rigour of the primary studies, any review is nearly worthless.

Take the 12 acupuncture trials, for instance, which the review authors included based not on an assessment of the studies but on a dodgy review published in a dodgy journal. Had they critically assessed the quality of the primary studies, they could have not stated that CAM therapies with the most robust evidence of efficacy for treatment of psoriasis …[include]… acupuncture. Instead they would have had to admit that these studies are too dubious for any firm conclusion. Had they even bothered to read them, they would have found that many are in Chinese (which would have meant they had to be excluded in their review [as many pseudo-systematic reviewers, the authors only considered English papers]).

There might be a lesson in all this – well, actually I can think of at least two:

1. Systematic reviews might well be the ‘Rolls Royce’ of clinical evidence. But even a Rolls Royce needs to be assembled correctly, otherwise it is just a heap of useless material.
2. Even top journals do occasionally publish poor-quality and thus misleading reviews.