Effects and feasibility of hyperthermic baths in comparison to exercise as add-on treatment to usual care in depression: a randomised, controlled pilot study

BACKGROUND: Limitations of current therapy of depression highlight the need for an immediately available, easily implementable add-on treatment option with high acceptance from patients. Hyperthermic baths (HTB) are a form of balneotherapy with head-out-of-water-immersion in a hot pool or tub at 40 °C for 15–20 min. A prior study suggests that HTB added to usual depression care can have antidepressant effects. METHOD: Single-site, open-label randomised controlled 8-week parallel-group pilot study at a university outpatient clinic. 45 medically stable outpatients with moderate depression as determined by the 17-item Hamilton Depression Rating Scale (HAM-D) score ≥ 18 and a score ≥ 2 on item 1 (Depressed Mood) were recruited. They were randomised to twice weekly HTB (n = 22) or a physical exercise program (PEP) of moderate intensity (n = 23). Primary outcome measure was the change in HAM-D total score from baseline (T0) to the 2-week time point (T1). Linear regression analyses, adjusted for baseline values, were performed to estimate intervention effects on an intention-to-treat (ITT) and per-protocol (PP) principle. RESULTS: Forty-five patients (HTB n = 22; PEP n = 23) were analyzed according to ITT (mean age = 48.4 years, SD = 11.3, mean HAM-D score = 21.7, SD = 3.2). Baseline-adjusted mean difference after 2 weeks was 4.3 points in the HAM-D score in favor of HTB (p < 0.001). Compliance with the intervention and follow-up was far better in the HTB group (2 vs 13 dropouts). Per protocol analysis only showed superiority of HTB as a trend (p = 0.068). There were no treatment-related serious adverse events. Main limitation: the number of dropouts in the PEP group (13 of 23) was higher than in other trials investigating exercise in depression. Due to the high number of dropouts the effect in the ITT-analysis may be overestimated. CONCLUSIONS: HTB added to usual care may be a fast-acting, safe and easy accessible method leading to clinically relevant improvement in depression severity after 2 weeks; it is also suitable for persons who have problems performing exercise training. TRIAL REGISTRATION: German Clinical Trials Register (DRKS) with the registration number DRKS00011013 (registration date 2016-09-19) before onset of the study.