Research integrity and transparency in CAM journals: an analysis of publication bias and reporting practices (1995–2023) in four leading journals

Background
Complementary and alternative medicine (CAM) remains widely used worldwide, yet longstanding concerns persist regarding the balance and reliability of the evidence presented in CAM journals.

Objective
To examine long-term trends in publication practices within leading CAM journals, with particular attention to changes in publication types and the prevalence of positive versus negative study outcomes as indirect indicators of potential publication bias.

Methods
We conducted a complete census of articles published in four leading CAM journals at two contemporary time points (2018 and 2023), replicating the design and classification framework of a seminal 2001 analysis covering 1995 and 2000. Articles were categorised by publication type, subject area, and author-reported study outcome (positive, negative, or inconclusive, corresponding to the “open” category used in the original 2001 study). Descriptive analyses were used to compare trends over time and with earlier findings.

Results
The total number of published articles increased substantially between the earlier and contemporary periods. The proportion of empirical studies, particularly clinical trials, rose over time. However, the prevalence of positive outcomes also increased markedly, with positive findings accounting for over 80% of published articles in the contemporary period, compared with 49% in the earlier study. Negative and inconclusive outcomes remained relatively infrequent.

Conclusions
Despite growth in publication volume and a shift toward empirical study designs, CAM journals continue to exhibit a pronounced predominance of positive outcome reporting. These findings suggest that longstanding concerns regarding publication bias in CAM publishing have not diminished over time and appear to have intensified, with selective publication and related reporting and dissemination practices plausibly contributing to the observed patterns. This has important implications for research integrity and evidence-based decision-making in medical practice.