A Cochrane review [Abstract] 1 included 10 studies with a total of 258 subjects. They had either dermatomyositis and polymyositis, muscle biopsy was used in 5 trials for diagnosis. The interventions studied included the following: intravenous immunoglobulin (IVIG), plasma exchange,azathioprine,prednisolone,methotrexate, ciclosporin,infliximab,eculizumab, oral dexamethasone and etanercept, either alone or in combinations.
An RCT 2 including 95 adult patients with active dermatomyositis compared IVIG 2 g/kg vs. placebo over 2-5 days every 4 weeks for 16 weeks. The patients who received placebo and those without confirmed clinical deterioration while receiving IVIg could enter an open-label extension phase for another 24 weeks. The primary end point was a response, defined as a Total Improvement Score (TIS) of at least 20 (indicating at least minimal improvement) at week 16 and no confirmed deterioration up to week 16. The TIS is a weighted composite score reflecting the change in a core set of 6 measures of myositis activity over time; scores range from 0 to 100, with higher scores indicating greater improvement.
At 16 weeks, a significantly higher percentage of patients receivin IVIG experienced at least minimal improvement in disease activity compared with placebo (79% vs. 44%; difference of 35 percentage points, 95% CI 17 to 53, p<0.001). The results for at least moderate improvement (TIS HASH(0x2fcfe80)40) and major improvement (TIS HASH(0x2fcfe80)60) were generally in the same direction as the results of the primary end-point analysis: TIS HASH(0x2fcfe80) 40 points in 68% vs. 23% (difference 45%, 95% CI 27% to 63%);TIS HASH(0x2fcfe80) 60 points in 32% vs. 8% (difference 24%, 95% CI 8% to 39%). Over 40 weeks, 282 treatment-related adverse events occurred in the IVIG group, including headache (in 42% of patients), pyrexia (in 19%), and nausea (in 16%). A total of 9 serious adverse events (including 6 thromboembolic events) occurred.
Comment:The quality of evidence is downgraded by indirectness (only short-term outcomes reported and lack of data for patients younger than 18).
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