Abstract: Twelve trials were found to be eligible for inclusion in this review. Seven trials with a variable risk of bias compared IVIg with PE in 623 severely affected participants. In five trials with 536 participants for whom the outcome was available, the mean difference (MD) of change in a seven-grade disability scale after four weeks was not significantly different between the two treatments: MD of 0.02 of a grade more improvement in the intravenous immunoglobulin than the plasma exchange group; 95% confidence interval (CI) 0.25 to -0.20. There were also no statistically significant differences in the other measures considered. Three studies including a total of 75 children suggested that IVIg significantly hastens recovery compared with supportive care. The primary outcome for this review, available for only one trial with 21 mildly affected children, showed significantly more improvement in disability grade after four weeks with IVIg than supportive treatment alone, MD 1.42, 95% CI 2.57 to 0.27. In one trial involving 249 participants comparing PE followed by IVIg with PE alone, the mean grade improvement was 0.2 (95% CI -0.14 to 0.54) more in the combined treatment group than in the PE alone group; not clinically significantly different, but not excluding the possibility of significant extra benefit. Another trial with 34 participants comparing immunoabsorption followed by IVIg with immunoabsorption alone did not reveal significant extra benefit from the combined treatment. Adverse events were not significantly more frequent with either treatment, but IVIg is significantly much more likely to be completed than PE. One trial in altogether 51 children showed no significant difference when the standard dose was given over two days rather than five days. A previous Cochrane review has shown that PE hastens recovery compared with supportive treatment alone. There are no adequate comparisons of IVIg with placebo in adults, but this review provides moderate quality evidence that, in severe disease, IVIg started within two weeks from onset hastens recovery as much as PE. Adverse events were not significantly more frequent with either treatment but IVIg is significantly much more likely to be completed than PE. Also, according to moderate quality evidence, giving IVIg after PE did not confer significant extra benefit. In children, according to low quality evidence, IVIg probably hastens recovery compared with supportive care alone. More research is needed in mild disease and in patients whose treatment starts more than two weeks after onset. Dose-ranging studies are also needed and one is in progress.

Plain-language summary: We included trials of IVIg compared to no treatment, dummy treatment, PE, immunoabsorption (in which specific antibodies are removed from blood) or other immune treatments. We also considered trials of IVIg added to another treatment. We found 12 trials. Some of these compared more than two treatments. - Seven trials compared IVIg with PE (in 623 participants with severe GBS). - One compared PE alone to PE followed by IVIg (in 249 participants). - Three compared IVIg with supportive care (in a total of 75 children). - One compared a two-day to a five-day IVIg treatment plan (in 51 children). - One compared IVIg with immunoabsorption (in 48 participants). - One compared IVIg plus immunoabsorption with immunoabsorption (in 34 participants). For this review, we chose change in a disability scale after four weeks’ treatment as the main measure of the effect of IVIg. Five of the trials comparing IVIg and PE measured change in disability. IVIg and PE produced a similar amount of improvement in disability in the 536 trial participants. This evidence was of moderate quality. Harmful effects were no more frequent with PE or IVIg, but people were more likely to finish a course of IVIg. In one trial involving 249 participants who received PE or PE followed by IVIg, there was slightly more improvement from PE and IVIg together. The effect was probably not large enough to be noticeable but the results do not rule out the possibility. This evidence was of moderate quality. Three studies in children suggested that IVIg speeds up recovery compared with supportive care. Only one used the disability scale. They provided low quality evidence. In one small trial in children, the effect on disability appeared similar with a standard dose over two days rather than five days. Giving IVIg after immunoabsorption provided no extra benefit over immunoabsorption alone. No conclusions can be drawn from the trial comparing IVIg with immunoabsorption. The risk of bias in the included studies was variable. More research is needed to find the best dose of IVIg in adults and children, and one trial of giving a second dose to people who otherwise would be expected to do badly is in progress. The evidence is current to December 2013.