After PSM, the characteristics of participants with and without CKD were similar, except for the following variables (including serum cotinine ≥ 0.015 ng/mL, serum hydroxycotinine ≥ 0.015 ng/mL, serum cotinine, serum hydroxycotinine, urinary albumin, urinary CR, albumin creatinine ratio, BUN, SCR and eGFR) (p < 0.05) (Table 2). Here, ALB is linked to chronic kidney disease.