Early-Stage Chronic Kidney Disease and Related Health Care Spending

Importance The global burden of chronic kidney disease (CKD) is substantial and potentially leads to higher health care resource use.Objective To examine the association between early-stage CKD and health care spending and its changes over time in the general population.Design, Setting, and Participants Cohort study using nationwide health checkup and medical claims data in Japan. Participants included individuals aged 30 to 70 years with estimated glomerular filtration rates (eGFR) of 30 mL/min/1.73 m(2) or greater at the baseline screening in 2014. Data analyses were conducted from April 2021 to October 2023.Exposure The CKD stages at baseline, defined by the eGFR and proteinuria, were as follows: eGFR of 60 mL/min/1.73 m(2) or greater without proteinuria, eGFR of 60 mL/min/1.73 m(2) or greater with proteinuria, eGFR of 30 to 59 mL/min/1.73 m(2) without proteinuria, and eGFR of 30 to 59 mL/min/1.73 m(2) with proteinuria.Main Outcome and Measures The primary outcome was excess health care spending, defined as the absolute difference in health care spending according to the baseline CKD stages (reference group: eGFR >= 60 mL/min/1.73 m(2) without proteinuria) in the baseline year (2014) and in the following 5 years (2015 to 2019).Results Of the 79 988 participants who underwent a health checkup (mean [SD] age, 47.0 [9.4] years; 22 027 [27.5%] female), 2899 (3.6%) had an eGFR of 60 mL/min/1.73 m(2) or greater with proteinuria, 1116 (1.4%) had an eGFR of 30 to 59 mL/min/1.73 m(2) without proteinuria, and 253 (0.3%) had an eGFR of 30 to 59 mL/min/1.73 m(2) with proteinuria. At baseline, the presence of proteinuria and an eGFR less than 60 mL/min/1.73 m(2) were associated with greater excess health care spending (adjusted difference, $178; 99% CI, $6-$350 for proteinuria; $608; 99% CI, $233-$983 for an eGFR of 30-59 mL/min/1.73 m(2); and $1254; 99% CI, $134-$2373 for their combination). The study consistently found excess health care spending over the following 5 examined years.Conclusions and Relevance In this cohort study of nationwide health checkup and medical claims data in Japan, early-stage CKD was associated with excess health care spending over the 5 examined years, and the association was more pronounced with a more advanced disease stage.