Methodological challenges in pilot trials of herbal medicine: barriers to evidence-based practice

Objectives: The growing popularity of herbal medicine (HM) underscores the need for high quality clinical trials to support its evidence-based integration. Pilot trials are essential for addressing methodological challenges in this field. This study evaluates the design quality, feasibility, and reporting of HM pilot trials, with a focus on their capacity to inform future full-scale studies. Study Design and Setting: A comprehensive collection of HM pilot trials was conducted using PubMed, Web of Science, and Em-base, based on predefined inclusion criteria. Data were extracted on trial characteristics, reporting quality, and progression to full-scale studies. To gather additional information on follow-up studies, authors of selected trials were contacted directly by email. Adherence to Consolidated Standards of Reporting Trials (CONSORT) guidelines for pilot trials was evaluated, and Poisson regression was applied to identify factors influencing reporting completeness. Results: A total of 123 HM pilot trials were reviewed, predominantly from Asia (78.1%). Trials most commonly addressed respiratory (14.6%), nervous (14.6%), and reproductive systems (13.0%). Key gaps in reporting included feasibility assessments (13.1%), sample size rationale (47.2%), and randomization methods (35.8%). HM-specific details, including ingredient processing, quality control, and safety assessments, were inconsistently reported. Among the trials, 4 (3.3%) progressed to full-scale studies. Factors such as trial registration (incidence rate ratio (IRR) = 1.20, 95% CI: 1.11-1.30) and protocol publication (IRR = 1.16, 95% CI: 1.08-1.24) were positively associated with reporting completeness. Moreover, an analysis of the origin of HMs revealed that modern HM trials were 4.7 times more likely to progress to full-scale studies compared to traditional HM trials (odds ratio = 4.70, 95% CI: 0.37-252.91), although the result did not reach statistical significance (P = .300). Conclusion: HM pilot trials, as they stand, are not yet equipped to reliably guide full-scale studies. Core issues in methodological rigor, particularly in feasibility assessment, sample size justification, and randomization processes, limit their effectiveness and integration into evidence-based practice. A dedicated checklist that merges pilot study standards with the unique needs of HM trials is essential. (c) 2025 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.