Clinical Diagnostic Workup
As previously described(20), a detailed medical history, blood tests, physical examination, oxygen saturation and blood pressure were obtained from all patients. Body mass indices (BMI; kg/m²) were assessed using BMI-centiles adapted to age, sex, and race. All further consultations with other medical specialists were conducted based on clinical presentation. Electroencephalogram (EEG), electrocardiogram (ECG), echocardiography, ultrasound of the abdomen and thyroid, chest-X-rays, lung function with lung clearance index (LCI) measurement, cranial or spinal magnetic resonance imaging, and Nerve Conduction Velocity (NCV) were performed, if necessary, based on clinical presentation. Demographic variables, preexisting diagnoses, and newly detected underlying diseases as well as long COVID-associated symptoms were documented. PASC associated symptoms were assessed through a questionnaire (see supplementary file) and/or medical history. Shortness of breath/exercise intolerance were associated via the six-minute walking test. Patients were systematically queried as to symptoms associated with long COVID or other somatic symptoms were included in the evaluation. An improvement was defined by less reported intensity, quantity of symptoms, and/or alleviation of restrictions in daily routines, and numbers of symptoms or less restrictions in daily routines caused by long COVID symptoms.