Geographical variation in kidney function testing and associations with health care costs among patients with chronic kidney disease and type 2 diabetes.

OBJECTIVES:Clinical practice guidelines recommend at least annual testing of estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (uACR) for patients with chronic kidney disease (CKD) and type 2 diabetes (T2D). This study assessed the adequacy of eGFR and uACR testing in this patient population across the United States. STUDY DESIGN:Observational real-world study. METHODS:Adults with CKD and T2D were identified from the Optum Clinformatics database (2015-2019). The eGFR and uACR tests were assessed nationally and by state. The proportions of tested patients and patients receiving adequate monitoring per clinical practice guidelines were analyzed during the 1-year period after T2D and CKD diagnosis, along with all-cause health care costs. RESULTS:Among 101,057 adults with CKD and T2D, 94.1% had at least 1 eGFR test and 38.7% had at least 1 uACR test over 1 year. Only 20.3% of patients had adequate uACR monitoring; this was much lower than observed for adequate eGFR monitoring (86.6%). The eGFR testing rates were high across states (range, 79.5% [Colorado] to 97.3% [Alabama]); conversely, uACR testing rates were uniformly lower and showed wider variation (range, 14.0% [Maine] to 58.9% [Hawaii]). Mean annual all-cause health care costs were $28,636 and increased with CKD GFR stage. Lower uACR testing rates were associated with higher health care costs at the state level (Pearson r = -0.55; P < .01). CONCLUSIONS:In the United States, uACR testing is underutilized, with large geographical variations in testing rates noted between states. Lower uACR testing rates were associated with higher health care costs. The lack of sufficient uACR testing raises concerns about CKD management in patients with T2D.