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Table 3 Regression-adjusted estimates of expenditures, prescription drug use, and adherence to medications 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
Expenditures
  Total expenditures $1,887a,b $1,360a $1,341
(1,864-1,910) (1,344-1,375) (1,336-1,347)
  Out-of-pocket expenditures $148a,b $546a $570
(146–150) (539–552) (567–572)
  Plan expendituresc $1,708a,b $822a $776
(1,687-1,729) (811–833) (772–780)
Expenditures on brand name medications    
  Total expenditures $1,325a,b $926a $898
  (1,305-1,346) (911–941) (893–903)
  Out-of-pocket expenditures $96a,b $374a $369
(94–98) (368–381) (367–371)
  Plan expendituresc $1,221a,b $560a $537
(1,202-1,240) (549–571) (533–540)
Expenditures exceeding the gap threshold 27.6%a,b 17.4%a 16.9%
(27.2-28.1) (17.0-17.8) (16.8-17.0)
Prescriptions    
  Total number of prescriptions 38.1a,b 25.1a 26.5
(37.8-38.4) (24.9-25.3) (26.4-26.5)
  Total number of brand name prescriptions 10.7a,b 6.4a 6.9
(10.5-10.8) (6.3-6.5) (6.87-6.92)
Adherence to medications    
  Diabetes drug adherence 62.5%a,b 57.7% 57.4%
(61.0-63.9) (56.0-59.4) (56.9-58.0)
  Hypertension drug adherence 65.6%a,b 64.2%a 62.4%
(64.9-66.3) (63.5-64.9) (62.2-62.6)
  Lipid-lowering drug adherence 59.6%a,b 57.0%a 55.6%
(58.5-60.6) (56.0-58.0) (55.3-55.9)
  1. LIS: low-income subsidy beneficiaries; GC: gap coverage; PDC, 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.
  2. Each model of medication adherence included only beneficiaries with the condition of interest. Estimates were adjusted for the individual beneficiary characteristics and clinical co-morbidities listed in Table 1 and for the residential census characteristics listed in Table 2.
  3. aSignificantly different from the Non-LIS/Non-GC group (p <0.05).
  4. bSignificantly different from the Non-LIS/GC group (p <0.05).
  5. cMeasures of plan cost for LIS beneficiaries is comprised of the cost to the plan plus subsidies.