Fig. 1

Identification criteria for CKD patients and definition of index date. CKD chronic kidney disease; ICD-10 International Classification of Diseases, Tenth Revision; RRT renal replacement therapy; SHC Specific Health Checkups. (1) Index date*: The first date of SHC after the initial diagnosis of CKD in the claims records. (2) Index date^†: The first date when they met the CKD criteria according to the SHC results. CKD patients were identified by meeting either or both of the following criteria: (1) having the disease codes for CKD coded by ICD-10 as shown in eTable 1 recorded in the claims database and (2) having an estimated glomerular filtration rate less than 60 ml/min per 1.73 m² or positive proteinuria according to the SHC results