The recent novel coronavirus disease 2019 (COVID-19) pandemic has led to unprecedented changes in behavior. We evaluated the current status of precautionary behavior and physical activity in chronic kidney disease (CKD) patients during the COVID-19 pandemic. Methods: A population of CKD patients (n = 306) registered in the Study on Kidney Disease and Environmental Chemicals (SKETCH, Clinical Trial No. NCT04679168) cohort recruited from June 2020 to October 2020 was included in the study. We conducted a questionnaire survey related to risk perception of COVID-19, precautionary behavior, and physical activity. Results: There were 187 patients (61.1%) with estimated glomerular filtration rate of <45 mL/min/1.73 m2 . This population showed a higher degree of risk perception for COVID-19 than the general population. Age was the most significant determinant of risk perception among CKD patients. During the pandemic, social distancing and hygiene-related behavior were significantly increased (p < 0.001). The frequency of exercise was decreased only in those who took regular exercise, without diabetes, or with a lower Charlson comorbidity index (CCI) (p < 0.001), with no change among the other groups. Socioeconomic status and comorbidities significantly affected behavioral characteristics regardless of the category. Education and income were significantly associated with precautionary behaviors such as staying at home and hand sanitizer use. Patients with higher CCI status significantly increased frequency of exercise (adjusted odds ratio, 2.10; 95% confidence interval, 1.01–4.38). Conclusion: CKD patients showed higher risk perception with active precautionary behavioral changes than the general population. Healthcare providers should be aware of the characteristics to comprise precautionary behavior without reducing physical activity.

Background/Aims: Stress is closely related to the deterioration of digestive disease. Melatonin has potent anti-inflammatory properties. The objective of this study was to determine the effect of water stress (WS) and sleep deprivation (SD) on intestinal microbiota and roles of melatonin in stressful condition. Methods: We used C57BL/6 mice and specially designed water bath for stress and SD for 10 days. We measured melatonin concentrations in serum, feces, and colon tissues by high-performance liquid chromatography. Genomic DNA was extracted from feces and amplified using primers targeting V3 to V4 regions of bacterial 16S ribosomal RNA genes. Results: Compared to the control, melatonin concentration was lower in the WS and SD. Fecal concentration was 0.132 pg/mL in control, 0.062 pg/mL in WS, and 0.068 pg/mL in SD. In colon tissue, it was 0.45 pg/mL in control, 0.007 pg/mL in WS, and 0.03 pg/mL in SD. After melatonin treatment, melatonin concentrations in feces and colon tissue were recovered to the level of control. Metagenomic analysis of microbiota showed abundance in colitogenic microbiota in WS and SD. Melatonin injection attenuated this harmful effect. WS and SD showed decreased Lactobacillales and increased Erysipelotrichales and Enterobacteriales. Melatonin treatment increased Akkermansia muciniphila and Lactobacillus and decreased Bacteroides massiliensis and Erysipelotrichaceae. Conclusions This study showed that stress and SD could affect intestinal dysbiosis and increase colitogenic microbiota, which could contribute to the aggravating digestive disease. Melatonin concentrations in feces and colon tissue decreased under WS and SD. Melatonin treatment brought recovery of melatonin concentration in colon tissue and modulating dysbiosis of intestinal microbiota.