Background: Pilot/feasibility studies are assumed to be associated with inflated effect size (ES) of meta-analyses, and whether acupuncture is used as an adjunctive therapy or not may influence the effect size.
Objectives: This study aims to explore the changes of ES in meta-analyses when adopting different criteria regarding inclusion of pilot/feasibility studies and compare the ES following usage pattern of acupuncture (alone or as an adjunctive therapy) across therapeutic areas.
Methods: Searches were conducted to identify systematic reviews with meta-analyses of acupuncture from January 2017 to December 2020. The summary ES were extracted from each meta-analysis. Individual studies included in the meta-analyses were classified into one of the following four categories: sample size (N ≤ 100, N ˃ 100) and usage (acupuncture alone or as an adjunctive therapy). The ES was recalculated following the sample size, except of small-sized studies, and compared with that of original study. Fixed and random effects models and meta-regressions were estimated. The potential independent variables identified by relevant literatures (types of outcome, acupuncture and conditions) were extracted and analysed.
Results: Until March 2023, searches are finished, and relevant studies are under review. Preliminary findings will be reported.
Conclusions: Results of this study can demonstrate the impact of pilot/feasibility studies and usage pattern of acupuncture for effect sizes of meta-analyses. Patient, public, and/or healthcare consumer involvement: None.