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Table 1 Characteristics of the study population and unadjusted outcomes stratified by type of medicare part D coverage (n = 344,817)

From: Patterns of prescription drug expenditures and medication adherence among medicare part D beneficiaries with and without the low-income supplement

  LIS N = 25,226 Non-LIS/GC N = 29,289 Non-LIS/Non-GC N = 290,302
Age, years (SD) 78.8 (7.2)a,b 78.6 (7.0)a 77.7 (6.7)
Gender (% female) 73.9a,b 60.8a 59.6
Co-morbid conditions
  Hypertension (%) 77.0a,b 73.0a 74.1
  Hyperlipidemia (%) 52.4a 52.4a 58.3
  Osteoarthritis (%) 33.1a 32.4a 31.5
  Diabetes (%) 31.6a,b 23.8a 24.5
  Chronic Obstructive Pulmonary Disease (%) 27.9a,b 20.1a 23.2
  Coronary Artery Disease (%) 26.9a,b 23.3a 25.0
  Atrial fibrillation (%) 25.8a 25.2a 24.7
  Non-skin cancer (%) 23.6a,b 33.9a 31.3
  Stroke (%) 20.7a,b 17.5a 17.0
  Mental health (%) 18.0a,b 15.9a 13.8
  Congestive Heart Failure (%) 17.8a,b 14.0a 12.5
  Peripheral Vascular Disease (%) 15.3a,b 11.2a 12.8
  Dementia (%) 12.0a,b 7.4a 6.8
  End-stage renal disease (%) 5.9a,b 4.6a 4.9
  Rheumatoid arthritis (%) 3.5a,b 2.4a 2.8
Expenditures 2006
  Total costs (SD) $2,085 (2,411)a,b $1,290 (1,495) $1,275 (1,439)
  Total out-of-pocket costs (SD) $159 (224)a,b $511 (608)a $544 (662)
  Plan costs (SD)c $1,926 (2,316)a,b 778 (1,028)a $731 (951)
  Total cost of brand name drugs (SD) $1,359 (2,105)a,b $729 (1,263)a $766 (524)
  Out-of-pocket cost of brand name drugs (SD) $93 (178)a,b $301 (533)a $318 (524)
  Plan cost of brand name drugs (SD)c $1,266 (2,034)a,b $428 (868)a $448 (857)
Total number of prescriptions (SD) 42 (33)a,b 25 (21)a 26 (22)
Total number of BM (SD) 12 (14)a,b 6 (8)a 7 (9)
Medication adherence
  Diabetes medications, PDC (%) 76.8 77.3a 76.1
  Diabetes medications, % adherence 59.4a 58.9 57.7
  Hypertension medications, PDC (%) 79.3a,b 80.1a 78.6
  Hypertension medications, % adherence 63.7a,b 65.7a 62.5
  Lipid-lowering medications, PDC (%) 73.2a,b 75.8a 73.0
  Lipid-lowering medications, % adherence 56.9a,b 59.8a 55.6
  1. LIS: Low-income subsidy beneficiaries; GC: gap coverage; SD: standard deviation; PDC: the proportion of days covered, which was calculated from dispensing data within each class of drugs; Adherence: defined as having a PDC ≥80% in the year or month for the entire regimen, allowing drug supply to carry over from month to month. Each model of medication adherence included only beneficiaries with the condition of interest.
  2. aSignificantly different from the Non-LIS/Non-GC group (p <0.05).
  3. bSignificantly different from the Non-LIS/GC group (p <0.05).
  4. cMeasures of plan cost for LIS beneficiaries is comprised of the cost to the plan plus subsidies.