Adoption and diffusion of SGLT2 inhibitors among cardiologists in medicare part D, 2019–2023: a provider-level observational study

Abstract Background Sodium–glucose cotransporter-2 (SGLT2) inhibitors are guideline-directed therapies for heart failure, yet real-world diffusion into cardiology practice remains incompletely characterized. This study evaluated adoption, prescribing intensity, subspecialty variation, geographic variation, and concentration of SGLT2 inhibitor use among cardiologists in Medicare Part D from 2019 to 2023. Methods We conducted an observational, provider-level study using Medicare Part D Prescriber–Provider Public Use Files, including all clinicians with a primary specialty designation of cardiology. Primary analyses focused on empagliflozin and dapagliflozin. Outcomes included annual observable adoption (presence of a non-suppressed prescribing record), prescribing intensity among adopters, prescribing concentration (raw and normalized for overall Part D prescribing volume), adoption by cardiology subspecialty, total drug spending, and state-level variation with confidence intervals. Results Among approximately 23,000 to 24,000 cardiologists annually, observable adoption increased from 4.5% in 2019 to 56.1% in 2023, with acceleration after 2021. Median prescribing intensity among adopters rose from 23 claims (interquartile range [IQR] 15–43) to 43 claims (IQR 21–90); early adopters prescribed nearly three times the intensity of late adopters after adjustment (incidence rate ratio, 2.96; 95% CI, 2.85–3.08). By 2023, adoption reached 91.6% among cardiologists with a subspecialty designation in advanced heart failure/transplant cardiology, compared with 56.4% among general cardiologists and 49.7% among interventional cardiologists ( P  < 0.001). Prescribing by raw claim volume remained concentrated, with the top 10% of prescribers accounting for 40.6% of total claims in 2023; this concentration was substantially attenuated, to 21.4%, after normalizing for each cardiologist’s overall Part D prescribing volume. Crude adoption varied substantially by state (25.6%-75.0% in 2023), though low-denominator states showed considerable estimate instability after empirical Bayes adjustment. Total Medicare Part D spending increased from $33.2 million in 2019 to $1.1 billion in 2023 in nominal dollars (28-fold in inflation-adjusted terms). Conclusions Observable SGLT2 inhibitor adoption among cardiologists increased rapidly, but a substantial portion of apparent geographic heterogeneity and prescribing concentration reflects practice volume and subspecialty composition rather than adoption behavior alone. Adoption approached ceiling levels among advanced heart failure/transplant cardiologists, while general and interventional cardiologists lagged behind, identifying a specific target for future implementation efforts.