Risk Factors for Developing CKD

This study was a large-scale, single-center, retrospective cohort study to clarify risk factors for developing CKD. We used the database at the Center for Preventive Medicine, St. Luke’s International Hospital, Tokyo, Japan. We analyzed the medical records of study subjects who underwent annual regular health check-up for general population at the center both in 2004 and 2009. When the study subjects had examinations more than once a year, we used only the first results in the same year to avoid double count. While all the population was able to access to the center, these medical examinations were out of insurance. Every subject and/or their companies paid for the examinations and each subject had identical physical and laboratory examinations. Serum creatinine was measured by enzymatic analysis and was calibrated to an isotope-dilution mass spectrometry (IDMS) standard. Serum Sodium was measured by ion-selective electrode measurements. The samples were measured using the BioMajesty^TM (NIHON KOHDEN Corporation, Tokyo, Japan) auto-analyzer. All blood samples were collected in the morning and performed in the same laboratory. Our population was ‘an apparently healthy population’ as they came to the center to have annual regular health check-up by themselves, and also provided a general history for comorbidities. Our study design allowed us to identify the development of CKD in apparently healthy people.
The study included subjects between 30 years and 85 years old at the 2004 examination. We excluded subjects with CKD in 2004 (baseline) because the study objective was to clarify risk factors for the development of new CKD. Furthermore, we excluded subjects with DM in 2004 because high blood glucose had large influences to the calculated osmolarity and DM is an established risk factor for CKD.