Development of chronic kidney disease in patients with non-alcoholic fatty liver disease: A cohort study

•NAFLD was associated with an increased risk of CKD development. •The association was progressive with increased severity of liver disease. •NAFLD may play a pathophysiologic role in CKD development. •NAFLD patients need to be carefully monitored for the development of CKD. Background & Aims Non-alcoholic fatty liver disease (NAFLD) has been associated with chronic kidney disease (CKD), but cohort studies are limited. We investigated the longitudinal association of NAFLD and its severity with the development of CKD. Methods We performed a retrospective cohort study of 41,430 adult men and women (average age, 48.9 y) without CKD at baseline who underwent repeated health check-up examinations from January 1, 2003, through December 31, 2013. NAFLD status was assessed by ultrasonography, and NAFLD severity was assessed by the NAFLD fibrosis score (NFS). Results The outcome was an incident CKD, defined as an estimated glomerular filtration rate less than 60 ml/min/1.73 m2. During 200,790 person-years of follow-up (median follow-up of 4.15 years), we identified 691 incident CKD cases. The multivariable-adjusted hazard ratio for CKD comparing participants with and without NAFLD was 1.22 (95% confidence interval [CI] 1.04–1.43). The risk of CKD increased progressively with increased NAFLD severity. The multivariable-adjusted hazard ratios for CKD comparing participants with NFS <−1.455 and those with NFS ≥−1.455 to participants without NAFLD were 1.09 (95% CI 0.91–1.32) and 1.58 (95% CI 1.30–1.92), respectively. The association was consistent across clinically relevant subgroups. Conclusion In a large cohort of adult men and women without CKD, NAFLD was associated with an increased risk of CKD development. NAFLD may adversely affect renal function and patients may need to be carefully monitored for an increased risk of CKD. Lay summary The presence of fatty liver is associated with the future decline of renal function. Thus, fatty liver patients need to be monitored regularly for renal function. Non-alcoholic fatty liver disease (NAFLD) has been associated with chronic kidney disease (CKD), but cohort studies are limited. We investigated the longitudinal association of NAFLD and its severity with the development of CKD. We performed a retrospective cohort study of 41,430 adult men and women (average age, 48.9 y) without CKD at baseline who underwent repeated health check-up examinations from January 1, 2003, through December 31, 2013. NAFLD status was assessed by ultrasonography, and NAFLD severity was assessed by the NAFLD fibrosis score (NFS). The outcome was an incident CKD, defined as an estimated glomerular filtration rate less than 60 ml/min/1.73 m2. During 200,790 person-years of follow-up (median follow-up of 4.15 years), we identified 691 incident CKD cases. The multivariable-adjusted hazard ratio for CKD comparing participants with and without NAFLD was 1.22 (95% confidence interval [CI] 1.04–1.43). The risk of CKD increased progressively with increased NAFLD severity. The multivariable-adjusted hazard ratios for CKD comparing participants with NFS <−1.455 and those with NFS ≥−1.455 to participants without NAFLD were 1.09 (95% CI 0.91–1.32) and 1.58 (95% CI 1.30–1.92), respectively. The association was consistent across clinically relevant subgroups. In a large cohort of adult men and women without CKD, NAFLD was associated with an increased risk of CKD development. NAFLD may adversely affect renal function and patients may need to be carefully monitored for an increased risk of CKD.