Proteinuria changes in kidney disease patients with clinical remission during the COVID-19 pandemic

BACKGROUNDS: Data on how lifestyle changes due to the coronavirus disease 2019 (COVID-19) pandemic have influenced the clinical features of kidney disease patients remain scarce. METHODS: This study retrospectively analyzed clinical variables in patients with stage G1–G4 chronic kidney disease (CKD) with complete or incomplete remission of proteinuria, who were managed in a nephrology outpatient clinic of a university hospital in Tokyo. The clinical variables during the COVID-19 pandemic (term 1, June–July 2020) were compared to those one year before the pandemic (term 0, June–July 2019). The urinary protein excretion (UPE) was used as the primary outcome measure. RESULTS: This study included 325 patients with stage G1–G4 CKD (mean age 58.5 years old, 37.5% female, 80.6% on renin-angiotensin aldosterone system inhibitors [RAASis], 12.0% on maintenance dose immunosuppression therapy) evaluated at term 0. The UPE at terms 0 and 1 was 247 (92–624) and 203 (84–508) mg/day [median (25(th)–75(th) percentile)], respectively; the value in term 1 was 18% lower than that in term 0 (p<0.001), with no marked difference in body weight, blood pressure, protein intake or urinary salt excretion. In multivariable analyses, incomplete remission of proteinuria in term 0 (odds ratio [OR] = 2.70, p = <0.001), RAASi use (OR = 2.09, p = 0.02) and decreased urinary salt excretion in term 1 vs. term 0 (OR = 1.94, p = 0.002) were identified as independent variables associated with reduced UPE in term 1 vs. term 0. No significant interactions between the variables were observed. CONCLUSION: In kidney disease patients receiving standard medical care from nephrologists, the UPE after the emergency declaration in relation to the COVID-19 pandemic was lower than before the declaration. The UPE reduction may be associated with reduced dietary salt intake during the pandemic in patients treated with RAASi for insufficient control of proteinuria. Our results support the current proposal to continue therapeutic approaches to these patients, which involve RAASi therapy along with optimizing dietary habits, even while dealing with the COVID-19 pandemic.