Effects of Balneotherapy for Patients With Post-COVID Syndrome

Participants were recruited in the multidisciplinary Post-COVID unit of the Hospital del Mar or in a primary care center in Barcelona (Spain). In addition, Caldes de Montbui's City Council also advertised the project for patient recruitment on its public website. Inclusion criteria were individuals ≥18 years old with a PACS diagnosis provided by a physician.

Exclusion criteria included patients with preexisting disorders to the severe acute respiratory syndrome (SARS) coronavirus (CoV) 2 infection that displayed an important clinical overlap with PACS i.e., fibromyalgia (FM), chronic fatigue syndrome, chronic pain, and generalized anxiety disorder and/or depression that required pharmacological treatment. Patients with chronic debilitating conditions that required active treatment were also excluded i.e. cancer, chronic viral infections, systemic autoimmune diseases, epilepsy, uncontrolled endocrine disorders, etc. Patients with fear of water, incontinence, severe venous insufficiency, physical disabilities that hindered performance of Balneotherapy (BT)/aquatic exercises, and those who reported a tendency for symptomatic low blood pressure were also excluded. Blood tests performed within 4 months or less before the initial visit were mandatory for preselection and were reviewed: patients with anaemia, chronic kidney disease (CKD) stage 4 or less, chronic liver insufficiency, thyroid function abnormalities, and in general, any significant blood test abnormality that could be associated with PACS-related symptomatology were excluded.

Included patients underwent initial visit in which clinical data was reviewed and registered. Participants were randomly assigned to the intervention or control group through a lottery method. Patients were asked to not vary their usual care or initiate any other kind of therapy during the duration of the study. Post-Acute COVID symptoms At the time of the initial visit several clinical parameters were registered including: age, sex Body Mass Index (BMI), date of SARS-CoV-2 infection, admission into the Intensive Care Unit (yes/no), Visual Analogue Scale (VAS), and a large array of PACS-related symptoms(yes/no) that were classified according to the system/organ affected

Study design The study was designed as a prospective randomized controlled study. Data was collected at 3 time points: 1) initial visit (baseline), 2) at the end of BT or one month after baseline in control group, and 3) one month after BT finalization or two months after baseline in control group. Balneotherapy (BT) intervention The BT intervention consisted of 3 weekly sessions on alternate days in groups of 8 during 4 weeks, i.e., 12 sessions in total. The weekly planning was structured as following:

1 st day: Pool, shower, inhalation and aquatic exercise 2 nd day: Pool, shower, inhalation. 3 rd day: Pool, shower, inhalation and aquatic exercise The exercise program was designed by qualified specialists from the Caldes de Montbui spa. Exercises were performed in the thermal water pool, at 32°C during 2 hours. At the start of the session, patients were instructed to inhale thermal water vapor for 10 minutes, alternating between nose and mouth. Subsequently they underwent a circular shower during 10 minutes with a very fine jet that ran from the ankles to the neck to activate circulation. The temperature of the water and the power of the jet was set by the patient.