Abstract: In the first version of this review there were six eligible trials concerning 649 participants comparing plasma exchange with supportive treatment. No new eligible trials have been identified in subsequent updates. Two other studies compared different numbers of plasma exchanges. Overall the included trials had a moderate risk of bias (in general, the studies were at low risk but all had a high risk of bias from lack of blinding). In one trial with 220 severely affected participants, the median time to recover walking with aid was significantly shorter with plasma exchange (30 days) than without plasma exchange (44 days). In another trial with 91 mildly affected participants, the median time to onset of motor recovery was significantly shorter with plasma exchange (six days) than without plasma exchange (10 days). After four weeks, moderate-quality evidence from the combined data of three trials accounting for a total of 349 patients showed that plasma exchange significantly increased the proportion of patients who recovered the ability to walk with assistance (risk ratio (RR) 1.60, 95% confidence interval (CI) 1.19 to 2.15). In five trials with 623 participants in total, moderate-quality evidence showed that the RR for improvement by one or more disability grades after four weeks was 1.64 (95% CI 1.37 to 1.96) times greater with plasma exchange. Participants treated with plasma exchange also fared better, according to moderate-quality evidence, in time to recover walking without aid (three trials with 349 participants; RR 1.72, 95% CI 1.06 to 2.79) and requirement for artificial ventilation (five trials with 623 participants; RR 0.53, 95% CI 0.39 to 0.74). More participants had relapses by the end of follow-up in the plasma exchange group than in the control group (six trials with 649 participants; RR 2.89, 95% CI 1.05 to 7.93; moderate-quality evidence). Despite this, according to moderate-quality evidence, the likelihood of full muscle strength recovery at one year was greater with plasma exchange than without plasma exchange (five trials with 404 participants; RR 1.24, 95% CI 1.07 to 1.45), and the likelihood of severe motor sequelae was less (six trials with 649 participants; RR 0.65, 95% CI 0.44 to 0.96). High-quality evidence from six trials with 649 participants could not confirm or refute a lower risk of death following plasma exchange compared to control (RR 0.86, 95% CI 0.45 to 1.65). Three trials (N = 556) provided details of serious adverse events during the hospital stay; combined analyses found no increase in serious infectious events compared to the control group (RR 0.91, 95% CI 0.73 to 1.13), nor were there clear differences in blood pressure instability, cardiac arrhythmias or pulmonary emboli. Moderate-quality evidence shows significantly more improvement with plasma exchange than with supportive care alone in adults with Guillain-Barré syndrome, without a significant increase in serious adverse events. According to moderate-quality evidence, there was a small but significant increase in the risk of relapse during the first six to 12 months after onset in people treated with plasma exchange compared with those who were not treated. Despite this, after one year, full recovery of muscle strength was more likely and severe residual weakness less likely with plasma exchange.

Plain-language summary: We carried out a wide search of medical databases for trials in which participants were randomly assigned to plasma exchange or no treatment except supportive care. We found six trials, which included 649 participants in total. All six trials compared plasma exchange with supportive treatment. All were at low risk of bias, except that participants and their carers were aware of the treatment given (they were not blinded). Two additional studies compared different numbers of plasma exchange and could not be included in the analysis but are discussed. Plasma exchange speeded improvement from GBS. It did not cause harm apart from being followed by a probable slight increase in risk of relapse. Despite this, plasma exchange probably increases the chance of complete muscle strength recovery after one year. No new trials have been done since the first publication of this review in 2001. However trials have been done comparing plasma exchange with intravenous infusion of human immune globulin (the antibody portion of plasma). These trials are included in another Cochrane review and show the effects of the two treatments are similar. The evidence is up to date to 18 January 2016.