Post-COVID syndrome (PCS) refers to symptoms that develop 3 months from the onset of COVID-19 with symptoms that last for at least 2 months and cannot be explained by an alternative diagnosis (Soriano, Murthy et al. 2022). The nature of the symptoms has not been a factor in the definition of PCS. The prevalence of PCS is estimated to be 43% of all severe acute respiratory syndrom coronavirus 2 (SARS-COV-2)-infected patients, with hospitalized patients more likely to suffer from persistent symptoms (54%) than non-hospitalized patients (32%). Women are more likely to experience PCS than men (incidence, 49% vs 32%, respectively) (Chen, Haupert et al. 2022). The most common symptoms are fatigue (23%), memory impairment (14%), dyspnea (13%), sleep disturbances (11%), and joint pain (10%) (Chen, Haupert et al. 2022). Headaches, myalgia, anxiety or depression are also frequently reported.
In terms of the type, variety and duration of symptoms, PCS resembles a clinical picture observed after various viral infections, such as Eppstein-Barr virus, herpes simplex virus or influenza virus, namely myalgic encephalomyelitis and chronic fatigue syndrome (ME/CFS). Here, too, patients mainly suffer from fatigue, impaired concentration and memory, and non-restorative sleep. Some authors consider post-COVID as a form of ME/CFS triggered by the SARS-CoV-2 infection or the immune response to the infection. The underlying pathophysiology likely depends on the different viruses but is incompletely understood. Similarly, the causes of PCS are unclear to date. Autoimmunity is suspected to play a major role in all post-virus syndromes. It may be triggered by the defense against infections and is probably maintained by similarity of endogenous proteins with pathogen components (molecular mimicry). In the context of this autoimmunity, antibodies against endogenous structures can also be formed, such as antinuclear antibodies, which are directed against components of the cell nuclei. Antibodies against α- and β-adrenergic receptors and muscarinic acetylcholine receptors, among others, have been detected in patients suffering from ME/CFS as well as in patients with PCS.
Many patients are limited in their daily lives by the symptoms that develop or persist after SARS-COV-2-infection and suffer from a diminished quality of life. To date, there is little evidence on potential therapies for these complaints. Immunoadsorption (IA) efficiently removes (auto-)antibodies from the circulation and has been proposed as a potential therapy for PCS. The current trial will investigate the efficacy of IA for the treatment of PCS.
40 participants with PCS and a PCFS-score of at least 2 will be included in each. Each participant will undergo 5 sessions of IA with an immunoglobulin-binding adsorber and 5 sham treatments or vice versa. Sham treatment will be performed in the same ways as IA, but the IA device will not be set up with an adsorber. The order of treatments (immunoadsorption first or sham first) will be randomized. The participants are blinded to the order of treatments. An intervention-free interval of 8 weeks will separate both treatment blocks (Addendum from February 2024: 40 patients additional with the same inclusion and exclusion criteria will be treated using the devices and materials of another manufacturer, following the same design, and the results will be evaluated separately.).
The primary outcome of the study is the efficacy of IA vs. sham, measured as changes in the PCFS (0-4), Chalder-fatigue scale (0-33), MFI-20 (20-100), Bell score (0-100), montreal cognitive assesment and the hand-grip strength before therapy compared to values after immunoadsorption and after sham-treatment. Secondary outcomes are (1) the number and severity of adverse events, (2) the prevalence of auto-antibodies like antinuclear antibodies, antibodies against adrenoreceptors and antibodies against muscarinic acetylcholine receptors in patients with PCS and (3) the change in concentration of the auto-antibodies in context of therapy and sham-treatment. In addition, various assessments (Complete blood count with differential, Antinuclear antibody Thyroid-stimulating hormone, C-reactive protein, Vitamin B12, Vitamin D, 25-dihydroxy, Ferritin, Urinalysis, ECG, spirometry, psychological questionaires) will be performed during screening period to be able to exclude other diseases as the cause of the PCS symptoms. In addition, safety-relevant parameters such as heart rate, blood pressure, electrolyte concentra-tions, fibrinogen concentration and the concentration of the immunoglobulin fractions are measured before and after each treatment.
The results of the study will inform future treatment strategies for PCS and will contribute to a better understanding of the pathophysiological insights behind the ongoing symptoms.
