Monday May 19 2008
Rosehip powder was used in the three studies
“Rosehip ‘better than painkillers’ for arthritis” is the headline in The Daily Telegraph today. Researchers have found that a powder made from Rosa canina (a wild variety of rosehip) is “three times more effective than standard paracetamol at relieving pain” and 40% more effective than glucosamine, the newspaper says.
The newspaper story is based on a meta-analysis of randomised controlled trials that compared rosehip with a placebo. The interpretations that can be drawn from the study are limited by the nature of the underlying evidence, as it was based on three short-term trials all using the same preparation of rosehip. The results provide the best evidence to-date that rosehip may reduce pain compared with no treatment. However, this meta-analysis was not set up to determine whether rosehip was better than current treatments and whether it is better than paracetamol or glucosamine remains to be seen. This can only be determined properly through studies that directly compare the treatments.
Where did the story come from?
Dr Robin Christensen and colleagues from Frederiksberg Hospital in Denmark, the University of California and the University of Copenhagen carried out this research. The study was funded by grants from the Oak Foundation, the Danish Rheumatism Association and Frederiksberg Hospital. It was published in the peer-reviewed medical journal: Osteoarthritis and Cartilage.
What kind of scientific study was this?
The study is a meta-analysis of randomised controlled trials. The researchers were interested in gathering all the high quality research (i.e. randomised controlled trials) into the use of Rosa canina hip powder treatment compared with placebo for osteoarthritis. There is conflicting evidence as to whether this treatment is effective or not.
The researchers searched well-known information databases for published studies and also conference proceedings for unpublished studies so that they could combine the results to see what effect the treatment had. This type of study – a systematic review – has increased power to detect a difference between treatment groups because they are adding together the results from the individual studies, considering their sample size (i.e. lending more “weight” to bigger studies). The researchers were primarily interested in what effects the powder had on pain reduction. They also assessed the use of “rescue” medications (e.g. other painkillers).
What were the results of the study?
The researchers found three randomised controlled trials that met their inclusion criteria; two in patients from Denmark and one in patients from Norway. In total, the studies included 306 patients who were randomly assigned to take Rosa canina powder or placebo to treat their osteoarthritis.
Combining the results from these studies showed that use of Rosa canina reduced pain scores to about a third of what they were in the placebo group. People taking the powder were also less likely to use “rescue” medication, i.e. other painkillers.
Overall, the researchers say that people taking Rosa canina were twice as likely to “respond to therapy” than those taking a placebo. There was no difference between the powder and the placebo in terms of side effects (e.g. gastrointestinal discomfort, diarrhoea, constipation etc.).
What interpretations did the researchers draw from these results?
The researchers conclude that their meta-analysis has shown that preparations with Rosa canina hip powder have a “small-to-moderate short-term effect” and a “small but clinically relevant” reduction in pain in people with osteoarthritis.
What does the NHS Knowledge Service make of this study?
This well-conducted meta-analysis suggests that preparations of Rosa canina hip powder are better at relieving pain than no treatment. The interpretations we can draw from the findings are essentially limited by the underlying evidence.
- Importantly, the studies were not comparing the powder with other painkillers. Only placebo-controlled trials were included (i.e. those comparing rosehip with no treatment). The researchers do measure whether rosehip reduces the use of “rescue” medication –which may include painkillers but they do not compare rosehip with paracetamol or with glucosamine as the newspaper suggests. The researchers mention other studies that have found that compared with placebo, paracetamol reduces pain by a smaller amount. However, this is not a valid way to compare treatments, i.e. results from one study compared with results from another study, as the people in the separate studies may have differed in important ways, such as the severity of their underlying condition.
- All included studies had short-term follow up times and were funded by the same manufacturer. The authors of this systematic review say that products from other manufacturers should also be tested or, ideally, the ingredient that is presumed to be the active one – called GOPO – should be isolated and purified and tested in that form.
- Researchers call for a large, longer term randomised controlled trial to be started following the results of their systematic review. They say that studies in future should use recognised scales that measure symptoms of osteoarthritis.
Overall, this systematic review provides good evidence that rosehip reduces pain associated with osteoarthritis. The three randomised controlled trials that provide evidence have only short-term follow-ups and larger trials with a longer follow up would provide a more definitive to this question. As the publication is based on a high quality method of combining the results of separate studies, it is the best evidence to-date on the effects of rosehip for patients with osteoarthritis.
Links to the headlines
Rosehip 'better than painkillers' for arthritis. The Daily Telegraph
, May 19 2008
Links to the science
Christensen R, Bartels EM, Altman RD, et al. Does the hip powder of Rosa canina (rosehip) reduce pain in osteoarthritis patients? – a meta-analysis of randomized controlled trials. Osteoarthritis Cartilage 2008; Apr 11 [Epub ahead of print]
Cepeda MS, Camargo F, Zea C, Valencia L. Tramadol for osteoarthritis. Cochrane Database Syst Rev 2006, Issue 3
Fidelix TSA, Soares BGDO, Trevisani VF M. Diacerein for osteoarthritis. Cochrane Database Syst Rev 2006, Issue 1
Towheed TE, Maxwell L, Judd MG, et al. Acetaminophen for osteoarthritis. Cochrane Database Syst Rev 2006, Issue 1