Data Source and Study Design
This retrospective, cross-sectional study used administrative claims data from the Humana Research Database (Louisville, KY) from January 1, 2015 to December 31, 2019. Humana, a large national health and wellness company, provides Medicare Advantage, a stand-alone prescription drug plan, and commercial health insurance across the US. This database contains de-identified enrolment information linked to medical (inpatient, emergency department, and outpatient); laboratory; and pharmacy claims data for individuals enrolled in Medicare or commercial health plans across the US. Some laboratory results data are available for ~ 60% of the patients. The Humana Healthcare Research Human Subject Protection Office reviewed this study and determined that it did not constitute human subject research and hence formal patient consent was not required. Only authorized employees of Humana Healthcare Research had access to de-identified, member-level data for analysis.
This study focused on patients with T2D enrolled in MAPD plans. This study included two cohorts—patients with T2D and existing ASCVD/HF (CVD cohort) and patients with T2D and at risk for ASCVD/HF (CVD risk cohort). Given the differences in treatment of older adults with T2D compared to younger adults, the study also evaluated GLA utilization by age group (50–64 years and ≥ 65 years) within each cohort.
Patients with ≥ 2 claims with T2D diagnosis codes (International Classification of Diseases, Ninth Edition [ICD-9] 250.x0, 250.x2; International Classification of Diseases, Tenth Edition [ICD-10] E11; Supplementary material Table S1) on different dates during a calendar year (2015–2019) and continuous enrolment in MAPD during the evaluation calendar year were included in the study. Patients were 50–89 years at the time of identification of T2D. Individuals with claims for type 1 diabetes and/or individuals with end-stage renal disease (renal transplant or dialysis) or with evidence of stage V CKD (estimated glomerular filtration rate < 15 ml/min/1.73 m2) at any time during the study were excluded.
Individuals with T2D were assigned to the CVD cohort and CVD risk cohort on an annual calendar year basis. To be included in the CVD cohort, patients had to have ≥ 1 inpatient claim (primary) or ≥ 2 outpatient claims for ASCVD/HF diagnosis or CVD procedures (Supplementary material Table S1) in the same calendar year as the T2D diagnosis or during subsequent calendar years after the T2D diagnosis. ASCVD diagnosis included myocardial infarction, acute coronary syndrome, carotid arterial disease, transient ischemic attack, coronary artery disease, unstable angina, ischemic stroke, and peripheral artery disease. After identification and classification to the CVD cohort for a given calendar year, patients were included as part of that cohort for the subsequent years as long as they were enrolled in a MAPD plan during each calendar year.
For inclusion in the CVD risk cohort, patients were required to have evidence of risk factors for ASCVD/HF during the same calendar year as the T2D diagnosis or during subsequent years after the T2D diagnosis (Supplementary material Table S2). These risk factors included CKD, hypertension, hyperlipidemia, microalbuminuria/macroalbuminuria, obesity, and smoking. If patients in the CVD risk cohort had an ASCVD/HF diagnosis or procedure in a given year, they were excluded from the CVD risk cohort for that year as well as any subsequent years.
Baseline demographic characteristics including age, sex, race/ethnicity, geographic location, and population density were evaluated. Patients eligible for both Medicare and Medicaid (dual eligible) or eligible for low-income subsidy (Medicare beneficiaries with income below 150% of poverty and limited resources; eligible for additional premium and cost-share assistance for prescription drugs under the Medicare Part D program) were flagged.
Use of different classes of GLAs for each year over the 5-year period was reported. The classes of GLAs included biguanides, sulfonylureas, thiazolidinediones, amylin agonists, meglitinides, α-glucosidase inhibitors, dipeptidyl peptidase-4 inhibitors, insulin, SGLT-2is, and GLP-1 RAs (Supplementary material Table S3). As per the Food and Drug Administration, SGLT-2is with proven cardiovascular benefit include empagliflozin, canagliflozin, and dapagliflozin. GLP-1 RAs with proven cardiovascular benefit (liraglutide, injectable semaglutide, and dulaglutide) are considered cardioprotective GLP-1 RAs. Oral semaglutide was not marketed during the study period, and therefore use of the oral form of semaglutide was not assessed. Patients were classified as receiving medication for that class if they had at least one prescription claim for that medication at any point during the year. If patients were on medications in multiple classes, they were counted in each class.