Achilles tendinopathy research has a gender data gap: A systematic review and meta-analysis

Purpose: A persisting gender bias has been recently highlighted in orthopaedics and sports medicine. The aim of this study was to evaluate the volume of gender-specific data and gender-specific results in the treatment of a common tendon disease, Achilles tendinopathy. Methods: Pubmed, Cochrane, and Web of Science were searched to identify all clinical studies focusing on Achilles tendinopathy treatment. The Visual Analogue Scale (VAS) and Victorian Institute of Sport Assessment-Achilles (VISA-A) data of women and men of the studies that disaggregated results by gender were collected, and a meta-analysis was conducted. Treatment response within and in between gender categories was evaluated, focusing on overall gender-disaggregated data, as well as within each of the three treatment categories: conservative treatment, injective treatment and surgical treatment. A formal risk of bias analysis was conducted using Downs and Black's grading system. Results: Out of the 8796 papers screened, 178 were included after the screening. The number of female study participants grew from 20% up to 1990 to 48% in the years 2019-2022. Only 373 out of 3423 (11%) female patients and 685 of 4352 (16%) male patients were found in sex-disaggregated studies. A meta-analysis was conducted on the 14 papers that reported sex-disaggregated data for VAS and VISA-A. The meta-analysis revealed that there was no difference in the overall treatment response between women and men and that both genders showed an overall significant treatment benefit in terms of VAS and VISA-A values. However, significant differences were documented within the treatment categories. While no differences were found in surgical studies, in conservative treatment studies, men experienced lower posttreatment VAS values (p = 0.004). The largest difference was found in injective treatments, with men experiencing a larger change in VAS values (men = -3.0, women = -1.0, p = 0.016) and higher posttreatment VISA-A values (p = 0.032). Conclusion: This systematic review and meta-analysis showed a lack of awareness of the importance of sex-specific data within Achilles tendinopathy treatment research. The proportion of female study subjects has grown over the years, but there is still a large data gap caused by the absence of sex-disaggregated data. The omission of sex-disaggregated data causes the loss of valuable knowledge on the true effectiveness of current Achilles tendinopathy treatment. The results of this study indicate that women profit less from available treatments, particularly injective approaches, which prompts further research for treatment adaptation by gender. Level of Evidence: Level IV.