All codes in codelist denote "Has CKD". If none of these codes are present we considered individuals as "No CKD". ckd_flag: Flags all codes that denote a diagnosis of CKD. transplant: Flags all codes related to kidney transplants dialysis: Flags all codes related to dialysis ckd_3_5: Flags all codes that denote a moderate to severe CKD, according to GFR category (>= stage 3) stage 1_2: Flags all codes related to a CKD diagnosis of mild CKD, according to GFR category (< stage 3)