Geographic variation in cardioprotective antihypertensive medication usage in dialysis patients

Abstract

Background: Despite their high risk of adverse cardiac outcomes, persons on long-term dialysis therapy have had lower use of antihypertensive medications with cardioprotective properties, such as angiotensin-converting enzyme (ACE) inhibitors/angiotensin receptor blockers (ARBs), β-blockers, and calcium channel blockers, than might be expected. We constructed a novel database that permits detailed exploration into the demographic, clinical, and geographic factors associated with the use of these agents in hypertensive long-term dialysis patients.

Study design: National cross-sectional retrospective analysis linking Medicaid prescription drug claims with US Renal Data System core data.

Setting & participants: 48,882 hypertensive long-term dialysis patients who were dually eligible for Medicaid and Medicare services in 2005.

Factors: Demographics, comorbid conditions, functional status, and state of residence.

Outcomes: Prevalence of cardioprotective antihypertensive agents in Medicaid pharmacy claims and state-specific observed to expected ORs of medication exposure.

Measurements: Factors associated with medication use were modeled using multilevel logistic regression models.

Results: In multivariable analyses, cardioprotective antihypertensive medication exposure was associated significantly with younger age, female sex, nonwhite race, intact functional status, and use of in-center hemodialysis. Diabetes was associated with a statistically significant 28% higher odds of ACE-inhibitor/ARB use, but congestive heart failure was associated with only a 9% increase in the odds of β-blocker use and no increase in ACE-inhibitor/ARB use. There was substantial state-by-state variation in the use of all classes of agents, with a greater than 2.9-fold difference in adjusted-rate ORs between the highest and lowest prescribing states for ACE inhibitors/ARBs and a 3.6-fold difference for β-blockers.

Limitations: Limited generalizability beyond study population.

Conclusions: In publicly insured long-term dialysis patients with hypertension, there were marked differences in use rates by state, potentially due in part to differences in Medicaid benefits. However, geographic characteristics also were associated with exposure, suggesting clinical uncertainty about the utility of these medications.