First, the laboratory assay and calibration methods have some differences for the measurement of creatinine and albumin between China and US and may lead to certain inconsistency; Second, no repeated measure for the creatinine and albumin were conducted, and thus the ‘persistence’ criterion of reduced kidney function or presence of albuminuria to define CKD may not be satisfied, which could lead to slight overestimation of CKD prevalence. Here, ALB is linked to chronic kidney disease.