title: Consistency of Hemoglobin A1c Testing and Cardiovascular Outcomes in Medicare Patients With Diabetes.
abstract: Annual hemoglobin A1c testing is recommended for patients with diabetes mellitus. However, it is unknown how consistently patients with diabetes mellitus receive hemoglobin A1c testing over time, or whether testing consistency is associated with adverse cardiovascular outcomes.
  
  
  
  We identified 1 574 415 Medicare patients (2002-2012) with diabetes mellitus over the age of 65. We followed each patient for a minimum of 3 years to determine their consistency in hemoglobin A1C testing, using 3 categories: low (testing in 0 or 1 of 3 years), medium (testing in 2 of 3 years), and high (testing in all 3 years). In unweighted and inverse propensity-weighted cohorts, we examined associations between testing consistency and major adverse cardiovascular events, defined as death, myocardial infarction, stroke, amputation, or the need for leg revascularization. Overall, 70.2% of patients received high-consistency testing, 17.6% of patients received medium-consistency testing, and 12.2% of patients received low-consistency testing. When compared to high-consistency testing, low-consistency testing was associated with a higher risk of adverse cardiovascular events or death in unweighted analyses (hazard ratio [HR]=1.21; 95% CI, 1.20-1.23; P<0.001), inverse propensity-weighted analyses (HR=1.16; 95% CI, 1.15-1.17; P<0.001), and weighted analyses limited to patients who had at least 4 physician visits annually (HR=1.15; 95% CI, 1.15-1.16; P<0.001). Less-consistent testing was associated with worse results for each cardiovascular outcome and in analyses using all years as the exposure.
  
  
  
  Consistent annual hemoglobin A1c testing is associated with fewer adverse cardiovascular outcomes in this observational cohort of Medicare patients of diabetes mellitus.
authors: Dartmouth-Hitchcock Medical Center, Lebanon, NH The VA Outcomes Group, White River Junction, VT The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Hanover, NH philip.goodney@hitchcock.org.
authors: Philip P
authors: PP
authors: Goodney
authors: Dartmouth-Hitchcock Medical Center, Lebanon, NH The VA Outcomes Group, White River Junction, VT.
authors: Karina A
authors: KA
authors: Newhall
authors: Dartmouth-Hitchcock Medical Center, Lebanon, NH.
authors: Kimon
authors: K
authors: Bekelis
authors: The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Hanover, NH.
authors: Daniel
authors: D
authors: Gottlieb
authors: Dartmouth-Hitchcock Medical Center, Lebanon, NH.
authors: Richard
authors: R
authors: Comi
authors: Dartmouth-Hitchcock Medical Center, Lebanon, NH.
authors: Sushela
authors: S
authors: Chaudrain
authors: The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Hanover, NH.
authors: Adrienne E
authors: AE
authors: Faerber
authors: The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Hanover, NH.
authors: Todd A
authors: TA
authors: Mackenzie
authors: The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Hanover, NH.
authors: Jonathan S
authors: JS
authors: Skinner
mesh_terms: D000368:Aged; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology*; D048909:Diabetes Complications / Q000097:blood; D003920:Diabetes Mellitus / Q000097:blood*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data*; D057216:Propensity Score; D014481:United States
chemical_list: D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
keywords: cardiovascular outcomes; diabetes mellitus; health disparities; health outcomes; hemoglobin A1c