Prevalence and association of dysnatremia with outcomes in hospitalized COVID-19 patients

Background: In the general population obesity is associated with increased risk of mortality. However, in ESKD patients obesity is associated with lower risk of mortality, particularly in dialysis patients (i.e. the obesity paradox). In COVID-19 patients, obesity exhibits a similar association with mortality as observed in the non-COVID-19 general population. Given the obesity paradox, we questioned the association of obesity with mortality in ESKD patients with COVID-19. Methods: Data from the European Renal Association COVID-19 Database (ERACODA) were analysed. Association of BMI (kg/m2), divided into: <18.5 (lean), 18.5-24.9 (normal weight), 25-29.9 (overweight), 30-34.9 (obese I) and ≥35 (obese II), with 3-month mortality was investigated using Cox proportional-hazards regression. Results were investigated for the total population and, dialysis patients and kidney transplant recipients separately. Results: In 3160 ESKD patients (mean age: 65 years, male: 61%), 99 patients were lean, 1151 normal weight (reference group), 1160 overweight, 525 obese I and 225 obese II. During follow-up of 3 months, 28%, 20%, 21%, 23% and 27% of patients died in the lean, normal weight, overweight, obese I and obese II category, respectively. In fully adjusted model, the HRs for 3-month mortality were 1.65 (95% CI:1.10, 2.47), 1.07 (95% CI:0.89, 1.28), 1.17 (95% CI:0.93, 1.46) and 1.71 (95%CI:1.27, 2.30) in lean, overweight, obese I and obese II vs normal weight patients (Figure). Results were similar among dialysis patients and transplant recipients (p-interaction=0.99). Conclusions: In ESKD patients with COVID-19, dialysis patients or kidney transplant recipients, obesity is associated with an increased risk of mortality at 3 months. This is contrary to obesity paradox generally observed in dialysis patients. There is need to investigate why in dialysis patients with COVID-19 the survival benefit of obesity is lost.