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. Author manuscript; available in PMC: 2018 Jan 1.
Published in final edited form as: Med Clin North Am. 2017 Jan;101(1):229–245. doi: 10.1016/j.mcna.2016.08.005

Table 4.

Effectiveness of interventions to reduce out-of-pocket costs: evidence from individual studies

Study Description of Intervention Effect on Adherencea
Chernew et al,59
 2008		 Reduction of copayment rates for
 ACE inhibitors, ARBs, and beta-
 blockers		 • MPR:
 ○ +2.6% points for ACE inhibi-
  tors/ARBs (P<.001)
 ○ +3.0% points for beta-blockers
  (P<.001)
Maciejewski
 et al,60 2010		 Reduction of copayment rates • MPR:
 ○ +3.4% for diuretics (P<.001)
 ○ 13.1% for ACE inhibitors
  (P<.001)
 ○ +2.7% for beta-blockers
  (P<.001)
 ○ +1.3% for calcium-channel
  blockers (P<.05)
Zhang et al,61
 2010		 Introduction of Medicare Part D
 coverage ($8/$20 copayments for
 generic/brand medications) to 3
 intervention groups with
 following baseline conditions:

  1. No coverage

  2. Coverage with low quarterly drug spending cap

  3. Coverage with high quarterly drug spending cap


[Comparison group had benefits
 similar to Part D coverage at
 baseline.]		 • MPR:
 ○ +13.5% points for group with
  no coverage at baseline (95% CI
  11.5–15.5)
 ○ +2.6% points for group with
  low cap at baseline (95% CI
  1.2–4.1)
 ○ +2.5% points for group with
  high cap at baseline (95% CI
  1.7–3.2)
Li et al,62 2012 Medicare Part D coverage gap, 3
 intervention groups with
 following baseline conditions:

  1. No coverage

  2. Generic-only coverage

  3. Brand and generic coverage


[Comparison group eligible for low-
 income subsidies during the gap.]		 • PDC <0.8 (low adherence)
 ○ OR = 1.60 (95% CI 1.50–1.71)
  for group with no coverage at
  baseline
 ○ OR = 1.50 (95% CI 1.30–1.73)
  for group with generic-only
  coverage at baseline
 ○ OR = 1.00 (95% CI 0.88–1.15)
  for group with brand and
  generic coverage at baseline
Volpp et al,63
 2014		 Financial incentive equal to
 copayments for all
 antihypertensive medications,
 which effectively eliminated
 copayments		 • MPR:
 ○ No effect (P = .74)

Abbreviations: ACE, angiotensin-converting enzyme; ARB, angiotensin receptor blocker; BP, blood pressure; CI, confidence interval; MPR, medication possession ratio; OR, odds ratio; PDC, proportion of days covered.

a

Only Volpp et al assessed the effect of the intervention on BP outcomes; no effect was detected.