The aim of this study was to estimate the incidence of COVID-19 disease in the French national population of dialysis patients, their course of illness and to identify the risk factors associated with mortality. Our study included all patients on dialysis recorded in the French REIN Registry in April 2020. Clinical characteristics at last follow-up and the evolution of COVID-19 illness severity over time were recorded for diagnosed cases (either suspicious clinical symptoms, characteristic signs on the chest scan or a positive reverse transcription polymerase chain reaction) for SARS-CoV-2. A total of 1,621 infected patients were reported on the REIN registry from March 16th, 2020 to May 4th, 2020. Of these, 344 died. The prevalence of COVID-19 patients varied from less than 1% to 10% between regions. The probability of being a case was higher in males, patients with diabetes, those in need of assistance for transfer or treated at a self-care unit. Dialysis at home was associated with a lower probability of being infected as was being a smoker, a former smoker, having an active malignancy, or peripheral vascular disease. Mortality in diagnosed cases (21%) was associated with the same causes as in the general population. Higher age, hypoalbuminemia and the presence of an ischemic heart disease were statistically independently associated with a higher risk of death. Being treated at a selfcare unit was associated with a lower risk. Thus, our study showed a relatively low frequency of COVID-19 among dialysis patients contrary to what might have been assumed.

We conducted the current study to investigate the clinical, laboratory, and histologic features at presentation and the outcome of renal sarcoidosis (RS). Exhaustive retrospective data were collected by the French Sarcoidosis Group. Forty-seven adult patients were assessed (30 male/17 female, M/F ratio: 1.76). Median estimated glomerular filtration rate (eGFR) was 20.5 mL/min per 1.73 m(2) (range, 4-93 mL/min per 1.73 m(2)). Moderate proteinuria was found in 31 (66%) patients (median, 0.7 g/24 h; range, 0-2.7 g/24 h), microscopic hematuria in 11 (21.7%) patients, aseptic leukocyturia in 13 (28.7%) patients. Fifteen of 47 (32%) patients had hypercalcemia (>2.75 mmol/L). Eleven of the 22 (50%) patients diagnosed between June and September had hypercalcemia compared with only 4 of the 25 (16%) cases diagnosed during the other months (p < 0.001). Thirty-seven patients presented with noncaseating granulomatous interstitial nephritis (GIN), and 10 with interstitial nephritis without granulomas. Apart from hypercalcemia, the clinical phenotype was also remarkable for the high frequency of fever at presentation. All patients initially received prednisone (median duration, 18 mo), 10 received intravenous pulse methylprednisolone. eGFR increased from 20 +/- 19 to 44 +/- 24.7 mL/min per 1.73 m(2) at 1 month (p < 0.001, n = 38), to 47 +/- 19.9 mL/min per 1.73 m(2) at 1 year (p < 0.001, n = 46), to 49.13 +/- 25 mL/min per 1.73 m(2) at last follow-up (p < 0.001, n = 47). A complete response to therapy at 1 year and at last follow-up was strongly correlated with complete response at 1 month (p < 0.01). Renal function improvement was inversely related to initial histologic fibrosis score. A complete response to therapy at 1 year was strongly correlated with hypercalcemia at presentation (p = 0.003). Relapses were purely renal (n = 3) and purely extrarenal (n = 10) or both (n = 4), often a long time after presentation, with in some cases severe cardiac or central nervous system involvement. We conclude that hypercalcemia and fever at presentation are often associated with RS; RS is most often and permanently responsive to corticosteroid treatment, but some degree of persistent renal failure is highly frequent and its degree of severity in the long run is well predicted from both histologic fibrotic renal score and response obtained at 1 month.