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 m2 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 m2 or greater without proteinuria, eGFR of 60 mL/min/1.73 m2 or greater with proteinuria, eGFR of 30 to 59 mL/min/1.73 m2 without proteinuria, and eGFR of 30 to 59 mL/min/1.73 m2 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 m2 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 m2 or greater with proteinuria, 1116 (1.4%) had an eGFR of 30 to 59 mL/min/1.73 m2 without proteinuria, and 253 (0.3%) had an eGFR of 30 to 59 mL/min/1.73 m2 with proteinuria. At baseline, the presence of proteinuria and an eGFR less than 60 mL/min/1.73 m2 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 m2; 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.