Scopolamine for patients with motion sickness: a systematic review and meta-analysis with trial sequential analysis.

Background: Scopolamine has been demonstrated to relieve motion sickness. However, repeated significance testing may increase false-positive results.

Objectives: Review the efficacy and safety of scopolamine in the prevention of motion sickness by performing a meta-analysis with Trial Sequential Analysis (TSA).

Material and methods: Randomized controlled trials (RCTs) compared scopolamine with other medications or placebo were included. Primary outcomes were nausea reported and head movement time.

Results: Twenty studies with 753 participants were included. Scopolamine had a greater reported reduction in nausea than placebo (relative risk [RR] 0.35; 95% confidence interval [CI] 0.24 to 0.52; p<0.00001; I² = 45%), while TSA showed the included sample size exceeded the required information size (RIS). There is no difference in head movement time between scopolamine and placebo (mean difference [MD] 2.02; 95% CI -1.2 to 5.25; p = 0.6; I² = 0%), while the included sample size did not reach RIS.

Conclusion: Scopolamine is effective for motion sickness nausea compared to placebo. The TSA recommends conducting more head movement trials to validate the objective efficacy of scopolamine.

Significance: Clarifying the efficacy of scopolamine for motion sickness, the TSA highlights the need for more prospective studies using head movement as an outcome.