Immunosuppressant and immunomodulatory treatment for dermatomyositis and polymyositis.

BACKGROUND

Idiopathic inflammatory myopathies are chronic diseases with significant mortality and morbidity. Whilst immunosuppressive and immunomodulatory therapies are frequently used, the optimal therapeutic regimen remains unclear. This is an update of a review first published in 2005.

OBJECTIVES

To assess the effects of immunosuppressants and immunomodulatory treatments for dermatomyositis and polymyositis.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (August 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 3 2011), MEDLINE (January 1966 to August 2011), EMBASE (January 1980 to August 2011) and clinicaltrials.gov (August 2011). We checked the bibliographies of identified trials and wrote to disease experts.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) or quasi-RCTs involving participants with probable or definite dermatomyositis and polymyositis as defined by the criteria of Bohan and Peter, or definite, probable or mild/early by the criteria of Dalakas. In participants without a classical rash of dermatomyositis, inclusion body myositis should have been excluded by muscle biopsy. We considered any immunosuppressant or immunomodulatory treatment. The two primary outcomes were the change in a function or disability scale measured as the proportion of participants improving one grade, two grades etc, predefined based on the scales used in the studies after at least six months, and a 15% or greater improvement in muscle strength compared with baseline after at least six months. Other outcomes were: the International Myositis Assessment and Clinical Studies Group (IMACS) definition of improvement, number of relapses and time to relapse, remission and time-to-remission, cumulative corticosteroid dose and serious adverse effects.

DATA COLLECTION AND ANALYSIS

Two authors independently selected papers, extracted data and assessed risk of bias in included studies. They collected adverse event data from the included studies.

MAIN RESULTS

The review authors identified fourteen 14 relevant RCTs. They excluded four trials.The 10 included studies, four of which have been added in this update, included a total of 258 participants. Six studies compared an immunosuppressant or immunomodulator with placebo control, and four studies compared two immunosuppressant regimes with each other. Most of the studies were small (the largest had 62 participants) and many of the reports contained insufficient information to assess risk of bias.Amongst the six studies comparing immunosuppressant with placebo, one study, investigating intravenous immunoglobulin (IVIg), showed statistically significant improvement in scores of muscle strength in the IVIg group over three months. Another study investigating etanercept showed some evidence of a steroid sparing effect, a secondary outcome in this review, but no improvement in other assessed outcomes. The other four randomised placebo-controlled trials assessed either plasma exchange and leukapheresis, eculizumab, infliximab or azathioprine against placebo and all produced negative results.Three of the four studies comparing two immunosuppressant regimes (azathioprine with methotrexate, ciclosporin with methotrexate, and intramuscular methotrexate with oral methotrexate plus azathioprine) showed no statistically significant difference in efficacy between the treatment regimes. The fourth study comparing pulsed oral dexamethasone with daily oral prednisolone and found that the dexamethasone regime had a shorter median time to relapse but fewer side effects.Immunosuppressants were associated with significant side effects.

AUTHORS' CONCLUSIONS: This systematic review highlights the lack of high quality RCTs that assess the efficacy and toxicity of immunosuppressants in inflammatory myositis.