Severe coronavirus disease 2019 and hypogammaglobulinemia: A prospective propensity-matched study of hemoadsorption

Background: The coronavirus disease 2019 (COVID-19) patients with hypogammaglobulinemia who are sick enough to require intensive care unit (ICU) admission exhibit high mortality rates. This study investigates whether the use of rescue hemoadsorption is associated with increased survival and/or improved clinical and biological parameters. Methods: In this prospective study, critically ill COVID-19 patients were consecutively enrolled, and serum protein electrophoresis was used to screen for hypogammaglobulinemia (defined as a gamma-globulin fraction below the 10th percentile and confirmed by a serum IgG level below 700 mg/dL). Twelve patients received hemoadsorption for immunomodulation. The same laboratory parameters were collected from 24 propensity-matched control patients who did not receive hemoadsorption. Results: There was no significant survival difference between patients treated with hemoadsorption and control patients. There was also no significant post-treatment improvement in the clinical parameters or sequential organ failure assessment (SOFA) scores for patients who received hemoadsorption compared to those who did not. Notably, 90% of all patients (32/36) died before day 28, regardless of whether they received hemoadsorption. An independent association between hypogammaglobulinemia and death within 28 days was found for all patients: Hazard ratio (HR) 0.32 (0.15, 0.66), P < 0.001. Conclusion: Hemoadsorption was not associated with increased survival in COVID-19 ICU patients with hypogammaglobulinemia. Our study highlights that a diagnosis of impaired humoral immunity could be a useful clinical predictor of high mortality and of non-response to hemoadsorption for patients with severe COVID-19.