Of the 413,177 patients with type 2 diabetes and CKD, 110,399 (26.7%) were classified as low risk of CKD progression, 253,188 (61.3%) as medium risk, and 49,590 (12.0%) as high risk (Supplementary Table S3). The median follow-up time was 2.7, 3.5, and 3.5 years for high-risk, medium-risk, and low-risk patients, respectively. The mean age at index date ranged from 58.0 years for low-risk patients to 66.5 years for high-risk patients. The majority of the sample are White (77.8–81.2% across risk groups), followed by African American (12.1–14.9%) and Asian (1.5–2.5%). Patients at higher risk had lower average eGFR (low-risk: 90.1 ml/min/1.73m2; medium-risk: 78.8; high-risk: 61.3) and substantially elevated average UACR (low-risk: 53.4 mg/g; medium-risk: 109.3; high-risk: 710.9). Notably, the baseline utilization of disease-control medications remained low in all groups (38.6–40.4% of patients used angiotensin-converting enzyme inhibitors and 19.2–20.5% used angiotensin II receptor blockers, with fewer patients using sodium glucose cotransporter 2 inhibitors (SGLT2i), steroidal mineralocorticoid receptor antagonists (MRA), and glucagon-like peptide 1 receptor agonists).

The observed risk of CKD progression aligned closely with the risk predicted by the Klinrisk model (Supplementary Figure S2). The median time to observed CKD progression was 8.5 years for high-risk patients but not reached for medium- and low-risk patients (Fig. 1). The observed rate of CKD progression at 2 years, 5 years, and 10 years were 18.6%, 36.5%, and 54.1% for high-risk patients, 3.7%, 11.7%, and 26.4% for medium-risk patients, and 1.5%, 5.7%, and 15.8% for low-risk patients. During the 1-year period following the CKD onset, 6533 (13.2%) high-risk, 8248 (3.3%) medium-risk, and 1037 (0.9%) of low-risk patients died.

Kaplan–Meier analysis of time to CKD progression in patients with CKD and type 2 diabetes stratified by risk of CKD progression. CKD progression was defined as onset of kidney failure or 40% decline in eGFR. The latter was determined as the first eGFR test result that was ≥ 40% lower than baseline eGFR; a confirmatory test between 90 days and 2 years after the first test was required unless the patient died or experienced kidney failure within 90 days after the first test. Kidney failure was defined as initiation of chronic dialysis, receipt of a kidney transplant, or eGFR < 10 ml/min/1.73 m2. Patients who did not experience CKD progression were censored at the end of follow-up. CI confidence interval, CKD chronic kidney disease, eGFR estimated glomerular filtration rate, NR not reached

Patients at greater risk of CKD progression had increased HRU compared with lower-risk patients (Supplementary Table S4). High-risk patients had an average of 1.48 inpatient admissions, 0.92 ER visits, and 34.88 outpatient visits per year, whereas low-risk patients averaged 0.23 inpatient admissions, 0.49 ER visits, and 25.07 outpatient visits annually. Moreover, medical costs increased with risk of CKD progression (Fig. 2). Annual total medical costs for high-risk patients ($51,087) were more than two times higher than those for medium-risk patients ($20,896) and more than three times higher than costs for low-risk patients ($14,616). Among high-risk patients, inpatient costs were the main cost driver ($36,636, 71.7% of total costs), followed by outpatient costs ($12,576, 24.6%) and ER costs ($1874, 3.7%). In contrast, for medium-risk patients, inpatient and outpatient costs were comparable (inpatient: $9886, 47.3%; outpatient: $9927, 47.5%), while in low-risk patients, the use of outpatient services accounted for the largest proportion of medical costs ($9040, 61.9%), doubling the costs associated with inpatient services ($4584, 31.4%).

Annual all-cause medical costs in patients with CKD and type 2 diabetes stratified by risk of CKD progression. Average medical costs were calculated as the average length of stay for inpatient admissions or average number of ER or outpatient visits multiplied by the corresponding unit cost (inpatient: $4424 per day; ER, $2039 per visit; outpatient: $361 per visit) estimated using data from Optum’s de-identified Clinformatics® Data Mart Database as described in a previous study [4]. CKD chronic kidney disease, ER emergency room, IP inpatient, OP, outpatient