Chronic kidney disease (CKD) is a common complication of type 2 diabetes mellitus, and is associated with considerable economic burden. CKD occurs in 20% of 40% of patients with diabetes, and costs incurred by patients with kidney disease and type 2 diabetes accounted for more than 50% of all Medicare costs in 2015. In addition, common comorbidities that include anemia, heart failure, and resistant hypertension are associated with worse health outcomes related to CKD. Annual spending for patients with CKD, type 2 diabetes, and heart failure was more than twice that for patients with CKD alone.
According to Kerstin Folkerts, MS, and colleagues, there are few real-world data available regarding costs and utilization of healthcare resources among patients with type 2 diabetes and CKD. Evidence that accounts for disease severity and additional comorbidities is even more scarce.
The researchers conducted a retrospective cohort study designed to describe patients with type 2 diabetes and CKD identified in US administrative claims data; the gold standard criteria for the diagnosis of kidney disease, results of specific laboratory tests for kidney function, were used to identify the patient population. A second study objective was an estimate of the annual healthcare resource use and costs among the patient population, both overall and stratified by disease severity and comorbidity subgroup. Results of the study were reported in the Journal of Managed Care & Specialty Pharmacy [2020;26(12):1506-1516].
The study period extended from January 1, 2008, through December 31, 2017. Patients ≥18 years of age with type 2 diabetes and newly recognized CKD were eligible. CKD was defined as at least two laboratory results for estimated glomerular filtration rate of <60 mL/min/1.73 m2 or at least two results for urine albumin-to-creatinine ratio (UACR) of values between ≥30 mg/g between 90 to 365 days apart. The index date was the date of the second laboratory result confirming CKD; CKD stage was defined on the index date according to Kidney Disease: Improving Global Outcomes (KDIGO) CKD stage criteria
Additional inclusion criteria were a baseline diagnosis of type 2 diabetes, defined as at least one inpatient or two outpatient International Classification of Diseases, Ninth/Tenth Revision, Clinical Modification codes for type 2 diabetes at least 30 to 365 days apart; patients were also required to have a minimum of 365 days of baseline enrollment in a commercial or Medicare Advantage health plan prior to cohort entry date.
During the study period, there were 106,369 patients with type 2 diabetes and newly recognized CKD identified. Mean age was 70.6 years, 56.5% were female, 57.7% were White, and approximately 73% were Medicare Advantage patients.
Among patients with commercial health coverage, the mean and median number of days of follow-up were 300 days and 365 days, respectively. Among the Medicare Advantage patients, mean and median follow-up was 317 days and 365 days, respectively. In the commercial health plan group, 35.1% had fewer than 365 days of follow-up; in the Medicare Advantage group, 28.8% had fewer than 365 days of follow-up.
In the overall cohort, the most common comorbidities were hypertension (89.4%), hyperlipidemia (83.2%), and pain disorders (69.1%). Common comorbidities related to cardiovascular disease included angina pectoris (24.2%), resistant hypertension (15.9%), coronary artery disease (13.5%), heart failure (11.1%), and atrial fibrillation (10.2%). Seventy-four percent were classified as CKD stage 3.
Average inpatient, emergency department (ED), and outpatient visits per person per year (PPPY) among patients with type 2 diabetes and newly recognized CKD were 0.3, 0.7, and 12.6, respectively. Mean duration of all in-patient stays per patient during follow-up was 3.2 days.
Patients with type 2 diabetes with newly recognized CKD and comorbid heart failure had nearly three times higher mean count of inpatient visits PPPY, three times longer average duration of inpatient stay, and twice the count of ED visits compared with patients without heart failure. Patients with type 2 diabetes and newly recognized CKD and comorbid anemia had double the mean number of hospital admissions PPPY and two times longer duration of inpatient stay compared with patients without anemia.
Among patients with type 2 diabetes and newly recognized CKD, those with advanced CKD had a seven-fold higher rate of hospitalization compared with those with an early disease stage. The mean duration of all inpatient visits was 10 times higher among patients with CKD stage 5 compared with patients with CKD stage 1.
For the overall cohort, mean annualized total cost was $24,029 PPPY. Mean costs for inpatient visits were $7223 PPPY, $5087 PPPY for outpatient visits, $1073 PPPY for ED visits, and $4672 PPPY for pharmacy costs.
Among patients with type 2 diabetes with newly recognized CKD and heart failure, total annualized costs were $41,951 PPPY; among those with anemia, total annualized costs were $33,127 PPPY. In all categories of care, mean annualized costs among patients with heart failure were higher than for those without heart failure: 2.6 times higher for inpatient visits, 1.8 times higher for outpatient visits, and 2.2 times higher for ED visits. Among patients with anemia, mean annualized cost was nearly double that of those without anemia ($11,338 PPPY vs $6292 PPPY, respectively).
Across worsening stages of CKD, annualized total cost was consistently higher; the higher costs were driven primarily by inpatient costs. Among patients with CKD stage 5, the total annualized cost was $17,432 PPPY among patients with normal UACR levels of <30 mg/g and $110,210 PPPY among patients with microalbuminuria (30-300 mg/g).
Study limitations cited by the authors included laboratory results being available in only 30% of patients in the overall Optum Clinformatics Data Mart database, the potential for misclassification of diagnoses due to use of claims data, the possible imprecision of laboratory measurements of kidney function, the inability to assess the degree of variation of cost estimates at the population level, and the possibility that the results are not generalizable to non-US-based patients and noncommercially insured populations in the United States.
In conclusion, the researchers said, “While CKD typically develops many years after the initial diagnosis of diabetes, it may also be present at the time of the type 2 diabetes diagnosis. Despite the high burden of CKD among patients with type 2 diabetes, many patients are unaware of their condition and face delays in CKD diagnosis and proper treatments. This study indicates that CKD patients with more advanced disease and other comorbidities have much higher healthcare resource use and cost. Given these findings, it is possible that earlier diagnosis of CKD and its complications in patients with type 2 diabetes, as well as interventions that are effective in halting or slowing the progression of CKD and treating other comorbid conditions, could result in substantial cost savings. The net cost benefit of such interventions will need to be assessed in future studies.”
- Researchers conducted a retrospective cohort study to describe patients with type 2 diabetes and chronic kidney disease (CKD) and estimate the annual healthcare resource utilization and costs in that patient population, overall and stratified by disease severity and comorbidity subgroup.
- The rate of hospitalization was 7-fold higher among patients with type 2 diabetes and advanced CKD compared with those with an early stage of CKD.
- Patients with type 2 diabetes with CKD and anemia or heart failure had higher use of healthcare resources and higher healthcare-related costs, compared with patients with type 2 diabetes with CKD and no comorbidities.