Diacerein for osteoarthritis.

Background: Osteoarthritis (OA) is one of the most prevalent musculoskeletal diseases. There is currently no consensus on what is the best treatment to improve OA symptoms and slow disease progression. Diacerein is an anthraquinone synthesised in 1980 that interferes with interleukin-1, an inflammatory mediator. It has been proposed that diacerein acts as a slow-acting, symptom-modifying and perhaps disease-structure-modifying drug for OA. This is an update of a Cochrane review first published in 2006.

Objectives: To assess the benefits and harms of diacerein for the treatment of adults with OA when compared with placebo and other pharmacologically active interventions (nonsteroidal anti-inflammatory drugs (NSAIDs) and other symptom-modifying, slow-acting drugs) for OA.

Search Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) - The Cochrane Library, Issue 10, 2013, MEDLINE (1966 to 2013), EMBASE (1980 to 2013), LILACS (1982 to 2013), and ACP Journal Club, and we handsearched reference lists of published articles. We also searched the World Health Organization International Clinical Trials Platform ( http://www.who.int/trialsearch/Default.aspx) to identify ongoing trials and screened reference lists of retrieved review articles and trials to identify potentially relevant studies. All searches were up to date as of March 2013. Pharmaceutical companies and authors of published articles were contacted. We searched the websites of the regulatory agencies using the keyword 'diacerein' in November 2013. No language restrictions were applied.

Selection Criteria: Studies were included if they were randomised or quasi-randomised controlled trials that compared diacerein with placebo or another active pharmacological intervention in participants with OA.

Data Collection And Analysis: Data abstraction and quality assessment were performed by two independent investigators, and their results were compared. The Cochrane risk of bias tool was used. The quality of evidence obtained was assessed using the GRADE approach.

Main Results: We identified three new trials (141 participants), and this updated review now includes 10 trials, totalling 2,210 participants. The most frequent risk of bias was incomplete outcome data, identified in approximately 80% of the studies. Allocation concealment and random sequence generation were unclear in 90% and 40% of the studies, respectively, because of poor reporting.Low-quality evidence from six trials (1,283 participants) indicates that diacerein has a small beneficial effect on overall pain (measured on a 100 mm visual analogue scale) at three to 36 months (mean difference (MD) -8.65, 95% confidence interval (CI) -15.62 to -1.68), which is equivalent to a 9% pain reduction in the diacerein group (95% CI -16% to -2%) compared with the placebo group. This benefit may not be clinically significant.No statistically significant differences in physical function (4 studies, 1006 participants) were noted between the diacerein and placebo groups (Lequesne impairment index, 0 to 24 points) (MD -0.29, 95% CI -0.87 to 0.28).Low-quality evidence from two trials (616 participants) on slowing of joint space narrowing (a decrease greater than 0.50 mm) in the knee or hip favoured diacerein over placebo (risk ratio (RR) 0.85, 95% CI 0.72 to 0.99), with an absolute risk difference of -6% (95% CI -15% to 2%) and a number needed to treat for an additional beneficial outcome (NNTB) of 14 (95% CI 8 to 203). Analysis of the knee joint alone (1 study, 170 participants) did not reach statistical significance (RR 0.94, 95% CI 0.51 to 1.74).None of the trials of diacerein versus placebo measured quality of life. According to one trial (161 participants), which compared diacerein versus non-steroidal anti-inflammatory drugs (NSAIDs), the quality of life of participants in the two groups (as assessed by the Short Form (SF)-36 health survey questionnaire (0 to 800 sum score)) did not differ significantly (MD -40.70, 95% CI -85.20 to 3.80).Low-quality evidence from seven trials showed significantly more adverse events in the diacerein group compared with the placebo group after two to 36 months, mainly diarrhoea (RR 3.52, 95% CI 2.42 to 5.11), with an absolute risk increase of 24% (95% CI 12% to 35%), and a number needed to treat for an additional harmful outcome (NNTH) of 4 (95% CI 3 to 7).No statistically significant differences in participant withdrawal due to adverse events were seen at two to 36 months for diacerein compared with placebo (RR 1.29, 95% CI 0.83 to 2.01).A search of regulatory websites found a recommendation from the European Medicines Agency (EMA) Pharmacovigilance Risk Assessment Committee (PRAC) that the marketing authorization of diacerein should be suspended across Europe because of harms (particularly the risk of severe diarrhoea and potentially harmful effects on the liver) outweighing benefits. However, this guidance is not final as the PRAC recommendation will be re-examined.

Authors' Conclusions: In this update, the strength of evidence for effectiveness outcomes was low to moderate. We confirmed that symptomatic benefit provided by diacerein in terms of pain reduction is minimal. The small benefit derived in terms of joint space narrowing is of questionable clinical relevance and was observed only for OA of the hip. With respect to adverse effects of diacerein, diarrhoea was most frequent. Given the recent guidance issued by the EMA recommending suspension of diacerein in Europe, the EMA website should be consulted for further recommendations regarding the use of diacerein.