2.3 | Urinary cfDNA purificationAfter collection from the patients, urine was centrifuged at 2000 g for 30 minutes, and urine supernatants were stored at −80°C. Urine was thawed in a water bath at 27°C, and 4-32 mL (median: 12 mL) supernatants was used for cfDNA purification after centrifugation at 16 000 g for 10 minutes. Urinary cfDNA extraction was carried out with a QIAamp Circulating Nucleic Acid Kit (QIAGEN, Hilden, Germany) according to the manufacturer's protocol, and cfDNAs were eluted by 50 μL AVE buffer. DNA concentration was meas- ured by a Qubit dsDNA High Sensitivity Assay Kit (Thermo FisherScientific, Waltham, MA, USA).