COVID-19-Related Discontinuation Impact on Patient-Reported Outcomes in Long-Term Thermal Therapy: A Single-Center Observational Study at Saturnia Thermal Springs

Background: Thermal therapy represents a well-established therapeutic approach for chronic musculoskeletal and respiratory conditions. To date, no studies have investigated the clinical effects of treatment interruption in thermal medicine. We aimed to evaluate the clinical impact of COVID-19 lockdown-induced thermal therapy discontinuation through validated patient-reported outcomes. Methods: This single-center observational, retrospective study (March 2020–June 2024) evaluated 97 patients receiving standardized thermal therapy at Saturnia Thermal Springs. Treatment protocols included balneotherapy, mud therapy, and inhalation treatments in cycles of 12–15 sessions, with maintenance protocols every 4–6 months. Primary outcomes were assessed through VAS and SF-36 PCS, with EQ-5D and PSQI as secondary outcomes. Results: Significant clinical deterioration occurred during treatment interruption (p < 0.001) in 77.7% of patients. Recovery patterns were duration-dependent, with the 6–7-year cohort showing faster recovery (mean time to baseline: 2.8 months) compared to the 3–5-year cohort (4.6 months). Effect sizes were substantial across all outcomes (Cohen’s d > 1.0), with EQ-5D scores showing duration-dependent improvement (mean improvement in 6–7-year cohort: 0.27). Conclusions: Thermal therapy interruption precipitates quantifiable clinical deterioration, with recovery patterns significantly influenced by pre-existing treatment duration. These findings support the essential nature of treatment continuity in thermal therapy protocols.