Geographic variation and racial disparities in adoption of newer glucose-lowering drugs with cardiovascular benefits among US Medicare beneficiaries with type 2 diabetes

Abstract

Background: Prior studies have shown disparities in the uptake of cardioprotective newer glucose-lowering drugs (GLDs), including sodium-glucose cotranwsporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP1a). This study aimed to characterize geographic variation in the initiation of newer GLDs and the geographic variation in the disparities in initiating these medications.

Methods: Using 2017-2018 claims data from a 15% random nationwide sample of Medicare Part D beneficiaries, we identified individuals diagnosed with type 2 diabetes (T2D), who had ≥1 GLD prescriptions, and did not use SGLT2i or GLP1a in the year prior to the index date,1/1/2018. Patients were followed up for a year. The cohort was spatiotemporally linked to Dartmouth hospital-referral regions (HRRs), with each patient assigned to 1 of 306 HRRs. We performed multivariable Poisson regression to estimate adjusted initiation rates, and multivariable logistic regression to assess racial disparities in each HRR.

Results: Among 795,469 individuals with T2D included in the analyses, the mean (SD) age was 73 (10) y, 53.3% were women, 12.2% were non-Hispanic Black, and 7.2% initiated a newer GLD in the follow-up year. In the adjusted model including clinical factors, compared to non-Hispanic White patients, non-Hispanic Black (initiation rate ratio, IRR [95% CI]: 0.66 [0.64-0.68]), American Indian/Alaska Native (0.74 [0.66-0.82]), Hispanic (0.85 [0.82-0.87]), and Asian/Pacific islander (0.94 [0.89-0.98]) patients were less likely to initiate newer GLDs. Significant geographic variation was observed across HRRs, with an initiation rate spanning 2.7%-13.6%.

Conclusions: This study uncovered substantial geographic variation and the racial disparities in initiating newer GLDs.

Fig 1. Adjusted initiation rate of newer GLDs and racial disparities in the initiation among Medicare beneficiaries with T2D in the entire US, by HRR.

(A) Adjusted initiation rate of newer GLDs among Medicare beneficiaries with T2D, by HRR; the initiation rate was calculated using multivariable Poisson regression model, adjusting for age, sex, Medicaid dual eligibility, rural/urban classification, T2D duration, number of GLD classes prescribed, CVD, and CKD. Each color corresponds to quintiles of adjusted initiation rate, ranging from 2.7% to 13.6%. (B) Racial disparities in the initiation of newer GLDs among Medicare beneficiaries with T2D, by HRR; the racial disparities in the initiation of newer GLDs were determined using multivariable logistic regression model, adjusting for age, sex, Medicaid dual eligibility, rural/urban classification, T2D duration, number of GLD classes prescribed, CVD, and CKD. The dark red color stands for HRRs with marked disparities in the initiation of GLDs that Black people were >50% less likely to initiate the newer GLDs compared to White people (n = 22 HRRs); the orange color stands for HRRs with disparities in the initiation of GLDs that Black people were 10–50% less likely to initiate the newer GLDs compared to White people (n = 57 HRRs); the yellow color stands for HRRs appeared to have disparities in the initiation of GLDs but without satanical significance (aOR <0.9 and p>.05); the grey areas stand for HRRs with negligible racial disparities in the initiation of GLDs.

Fig 2. Adjusted initiation rate of newer GLDs and racial disparities in the initiation among Medicare beneficiaries with T2D in Florida state, by HRR.

(A) Adjusted initiation rate of newer GLDs among Medicare beneficiaries with T2D in Florida state, by HRR; each color corresponds to quintiles of adjusted initiation rate, ranging from 4.8% to 8.3%.(B) (C) Racial disparities in the initiation of newer GLDs among Medicare beneficiaries with T2D in Florida state, by HRR; the racial disparities in the initiation of newer GLDs were determined using multivariable logistic regression model, adjusting for age, sex, Medicaid dual eligibility, rural/urban classification, T2D duration, number of GLD classes prescribed, CVD, and CKD. (B) presents the racial disparities between non-Hispanic Black vs. non-Hispanic White (referent); (C) presents the racial disparities between Hispanic vs. non-Hispanic White (referent).