Clinical effects of Kneipp hydrotherapy: a systematic review of randomised controlled trials

OBJECTIVE: Hydrotherapy is a traditional prevention and treatment strategy. This study’s aim is to systematically review all available randomised controlled trials (RCTs) investigating clinical effects of hydrotherapy according to Kneipp which is characterised by cold water applications. METHODS: RCTs on disease therapy and prevention with Kneipp hydrotherapy were included. Study participants were patients and healthy volunteers of all age groups. MEDLINE (via PubMed), Scopus, Central, CAMbase, and opengrey.eu were systematically searched through April 2021 without language restrictions and updated by searching PubMed until April 6th 2023. Risk of bias was assessed using the Cochrane tool version 1. Results Twenty RCTs (N=4247) were included. Due to high heterogeneity of the RCTs, no meta-analysis was performed. Risk of bias was rated as unclear in most of the domains. Of 132 comparisons, 46 showed significant positive effects in favour of hydrotherapy on chronic venous insufficiency, menopausal symptoms, fever, cognition, emotional function and sickness absenteeism. However, 81 comparisons showed no differences between groups and 5 were in favour of the respective control group. Only half of the studies reported safety issues. CONCLUSION: Although RCTs on Kneipp hydrotherapy seem to show positive effects in some conditions and outcomes, it remains difficult to ascertain treatment effects due to the high risk of bias and heterogeneity of most of the considered studies. Further high-quality RCTs on Kneipp hydrotherapy are urgently warranted. PROSPERO REGISTRATION NUMBER: CRD42021237611.