Proteinuria in COVID-19: prevalence, characterization and prognostic role (preprint)

Background: Proteinuria has been commonly reported in patients with COVID-19, suggesting a renal involvement in this infection. However, only dipstick tests have been used thus far. Here, the quantification and characterization of proteinuria and hematuria are investigated. Their potential association with mortality was assessed. Methods: This retrospective, observational and monocentric study includes 153 patients hospitalized with COVID-19 between March 28th and April 30th 2020, in whom total proteinuria and urine α1-microglobulin (a marker of tubular injury) have been measured. Association with mortality was evaluated with a follow-up until May 7th 2020. Results: According to the Kidney Disease Improving Global Outcomes staging, 14% (n=21) had stage 1 proteinuria (<150 mg/g of urine creatinine), 42% (n=64) had stage 2 (between 150 and 500 mg/g) and 44% (n=68) had stage 3 (over 500 mg/g). Urine α1-microglobulin concentration was higher than 10 or 15 mg/g in 94% and 89% of patients, respectively. After a median follow-up of 27 [14;30] days, the mortality rate reached 18%. Total proteinuria and urine α1-microglobulin (as continuous and/or categorical variables) were associated with mortality in unadjusted and adjusted models. This association was even stronger in subgroups of patients with normal renal function or without urinary catheter. Conclusions: Proteinuria is frequent in patients with COVID-19. Its characterization suggests a tubular origin with increased urine α1-microglobulin. Tubular proteinuria seems associated with mortality in COVID-19.

Risk factors for mortality in a multicenter cohort of mechanically ventilated COVID-19 patients in Belgium. (preprint)

Background: Considering the high mortality rate of severe Covid-19 patients, it is necessary to identify prognostic factors and therapies which could be valuable in this setting.Methods: The method consisted in a multicentric retrospective analysis in all consecutive Covid-19 patients admitted to intensive care unit (ICU) and mechanically ventilated for more than 24 hours from March 1 to April 25, 2020.Admission date, age, sex, body mass index, underlying conditions, treatments, physiological values, use of vasopressors, renal replacement therapy and extracorporeal membrane oxygenation, duration of mechanical ventilation, length of ICU stay, ICU and ventilator-free days at day 42 were collected. Primary outcome was survival. Simple and multiple time-dependent Cox regression models were used to assess the effects of factors on survival. Results: Out of 2003 patients hospitalized for SARS-CoV-2, 361 were admitted to the participating ICUs, 257 were ventilated for more than 24 hours and 247 were included in the study. The length of stay in ICU was 21 (12-32) days and the mortality rate was 45%. Using multiple regression, risk factors for mortality were age, high serum creatinine value, low mean arterial pressure, low lymphocytes count on day 0 and the absence of corticosteroid therapy during the first week of mechanical ventilation. The mortality rate of the patients who received corticosteroids was 34% and 48% for patients who did not (p = 0.01).Conclusion: In this multicenter cohort, the mortality of patients with SARS-CoV-2 pneumonia treated with mechanical ventilation was high. The risk factors for mortality included age, renal and circulatory dysfunction, lymphopenia and the absence of corticosteroid therapy during the first week of mechanical ventilation.