Summary of findings for the main comparison. Intravenous immunoglobulin versus placebo for inclusion body myositis.

Intravenous immunoglobulin versus placebo for inclusion body myositis
Patient or population: people with inclusion body myositis Settings: Intervention: intravenous immunoglobulin Comparison: placebo
Outcomes	Illustrative comparative risks* (95% CI)		Relative effect (95% CI)	No of participants (studies)	Quality of the evidence (GRADE)	Comments
	Assumed risk	Corresponding risk
	Placebo	Intravenous immunoglobulin
Change in muscle strength at 6 months (%)	Not estimable	Not estimable	Not estimable	78 (3 studies)	See comment	2 of the 3 studies assessed change in muscle strength at 3 months and the other at 6 months. Data were not suitable for meta‐analysis.
Change in muscle strength at 12 months (%) ‐ not measured	‐	‐	‐	‐	‐	‐
Change in muscle mass at 6 months (%) ‐ not measured	‐	‐	‐	‐	‐	‐
Change in handgrip strength at 6 months (%) ‐ not measured	‐	‐	‐	‐	‐	‐
Change in timed walk at 6 months (%) e.g. 10‐metre or 6‐minute walk test at 6 months ‐ not measured	‐	‐	‐	‐	‐	‐
Significant adverse events	Not estimable	Not estimable	Not estimable	78 (3 studies)	See comment	Dalakas 1997: unclear whether dropouts from treatment or placebo group. Dalakas 2001: treatment group withdrawals = 0; placebo group withdrawals = 1. Walter 2000: 2 withdrawals but unspecified whether from treatment or placebo group
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.