The Consolidated Standards of Reporting Trials (CONSORT) recommends reporting adverse events (AEs) and dropouts (DOs) with their definitions. The purpose of this study was to identify how AEs and DOs were reported in randomized controlled trials of therapeutic exercise for knee osteoarthritis (OA).
Data sources were the Cochrane Library, Embase, PubMed, and CINAHL. Databases were searched to identify randomized controlled trials of therapeutic exercise for knee OA published from January 1, 1980, through July 23, 2020. Researchers independently extracted participant and intervention characteristics and determined whether a clear statement of and reasons for AEs and DOs existed. The primary outcome was exercise-related harm. Physiotherapy Evidence Database (PEDro) scoring described study quality and risk of bias. Descriptive and inferential statistics characterized results. Meta-analysis was not performed due to data heterogeneity.
One hundred and thirteen studies (152 arms) from 25 countries were included, with 5909 participants exercising. PEDro scores ranged from 4 to 9. Exercise intensity was not specified in 57.9% of exercise arms. Fifty studies (44.2%) included an AE statement and 24 (21.2%) reported AEs, yielding 297 patients. One hundred and three studies (91.2%) had a DO statement. Sixteen studies (15.5%) provided reasons for DOs that could be classified as AEs among 39 patients, yielding a 13.1% increase in AEs. Thus, 336 patients (6.0%) experienced exercise-related harm among studies with a clear statement of AEs and DOs. A significant difference existed in misclassification of DOs pre- and post-CONSORT-2010 (12.2% vs 3.1%; $\chi^{2}_{1} = 21.2$).
More adherence to the CONSORT statement is needed regarding reporting of and defining of AEs, DOs, and therapeutic exercise intensity; however, despite this, therapeutic exercise seems to be associated with minimal risk of harm.
In some studies, the reason for DOs could be considered AEs, leading to potential underreporting of harm. Improvements in reporting of harm were found pre- and post-CONSORT-2010. Greater clarity regarding AE and DO definitions and therapeutic exercise intensity are needed to determine safe dosing and mode of therapeutic exercise for knee OA.