Table 2.
The Impact of Medicare Part D on Specific Drug Utilization and Out‐of‐Pocket Costs
| Citation | Study Population | Data Sources | Drug Utilization Outcomes | Out‐of‐Pocket Cost Outcomes |
|---|---|---|---|---|
| Longitudinal data | ||||
| Cheng and Rascati (2012) | Medicare beneficiaries ≥65 with arthritis in 2008, compared to 2005 (N = 2,484) | Survey (Medical Expenditure Panel Survey), 2005–2008 | Median prescription fills per year increased from 28.4 to 32.6. (14.6% change, p = .014) | Median out‐of‐pocket (OOP) drug expenditures decreased by $151 (25.2% change, p < .001) |
| Donohue et al. (2010) | Pennsylvania beneficiaries ≥65 with diagnosed heart failure who transitioned from no or limited drug coverage ($150 or $350 caps) to Part D coverage, compared to those with continuous no‐cap employer‐sponsored coverage (total N = 6,950) | Administrative (pharmacy and medical claims, enrollment data), 2003–2007 | Relative to the comparison group, individuals who previously lacked drug coverage filled 6 more cardiovascular prescriptions annually (adjusted ratio of prescription counts = 1.36, 95% CI: 1.29–1.44, p < .001) and the no‐coverage group experienced significant increases (p = .01 or lower) in the likelihood of good adherence to all drug classes and combinations, except for aldosterone‐inhibiting diuretics (p = .85) | — |
| Duru et al. (2014) | Beneficiaries ≥65 with a coronary stent placement not receiving low‐income subsidies with or without gap coverage, compared to those receiving low‐income subsidies (N = 2,967) | Administrative (pharmacy claims), 2007 | Low‐income subsidy enrollees were had higher proportions of days covered overall and for those with stents (>80% adherence overall: 54.8% vs. 47.6%, p = .008; >80% adherence among patients with drug‐eluting stents, 59.1% vs. 51.7%, p = .022); no statistically significant differences in early discontinuation of clopidogrel after coronary stent placement | — |
| Fowler et al. (2013) | Pennsylvania community‐dwelling Medicare Advantage enrollees ≥65 with three types of continuous coverage: (1) no‐gap coverage, (2) $150 cap, and (3) $350 cap; compared to those with generous employer‐sponsored coverage without a cap from 2004 to 2007 | Administrative (pharmacy and medical claims, enrollment data), 2004–2007 | Antidementia prescriptions per month increased in all coverage groups (p < .001); compared to those with generous insurance, beneficiaries with no‐gap coverage increased annual antidementia prescriptions filled by 38% (p < .001); compared to the no‐cap group, those without any coverage or with a $350 cap pre–Part D had a 36% (p = .002) and 15% (p = .003) increase in any antidementia prescription use | — |
| Kircher et al. (2014) | Medicare beneficiaries ≥65 with cancer, compared to near‐elderly aged 55–63 with cancer (N = 6,607) | Survey (Medical Expenditure Panel Survey), from 2002 to 2010 | No statistically significant differences in utilization | Compared to changes among near‐elderly, OOP costs among beneficiaries decreased by $356 per person (p = .02) |
| Lim, Jung, and Shi (2013) | Medicare beneficiaries with depression, compared to (1) Medicaid beneficiaries, (2) dual‐eligibles, and (3) those with private coverage (N = 22,592) | Survey (Medical Expenditure Panel Survey), from 1997 to 2009 | Compared to Medicaid beneficiaries, Medicare beneficiaries’ antidepressant use increased post–Part D ((aOR) = 1.35, CI = 1.05–1.72); no significant changes compared to other control groups | — |
| Vaidya, Blazejewski, and Pinto (2012) | Diabetic patients ≥65, compared to near‐elderly patients aged 57–64 (N = 5,961) | Survey (Medical Expenditure Panel Survey), 2004–2008 | The percentage of elderly patients prescribed statins increased significantly from 55.05 to 61.25% (p = .002), while there was no significant increase in statin prescriptions among the near‐elderly | — |
| Yusuf et al. (2014) | Medicare Part D beneficiaries on dialysis not receiving low‐income subsidies, compared to those receiving low‐income subsidies (N = 198,349 (2007); 209,972 (2008); 220,051 (2009); 231,320 (2010)) | Administrative (Center for Medicare and Medicaid U.S. Renal Data System), from 2007 to 2010 | The odds of using phosphate binders, intravenous vitamin D analogs, and calcimimetic are higher among patients with low‐income subsidies (OR = 1.17 – 2.38); yet the odds of using oral vitamin D analog is lower among patients with low‐income subsidies (OR = 0.70 – 0.96) | Patients without low‐income subsidy pays higher OOP costs for all medications (2007: $113 vs. $8.15; 2008: $115.44 vs. $8.03; 2009: $112.46 vs. $8.26; 2010: $111.51 vs. $8.74) |
| Zhang et al. (2010a) | Pennsylvania beneficiaries ≥65 with: (1) no drug coverage, (2) relatively poor coverage ($150 quarterly cap, with $600 annual maximum), or (3) relatively good coverage ($350 quarterly cap) pre–Part D; compared to those with continuous retiree health benefits with no deductible and $10/$20 copayments irrespective of their total drug spending (N = 20,889) | Administrative (enrollment data and pharmacy and medical claims), 2003–2007 | Relative to the changes in the comparison group, medication possession ratios improved 13.4 (95% CI: 10.1–16.8), 17.9 (95% CI: 13.7–22.1) and 13.5 (95% CI: 11.5–15.5) percentage points among those with hyperlipidemia, diabetes, and hypertension in the group without prior drug coverage; less improvement among those with limited prior drug benefits; drug adherence increased after Part D among beneficiaries without prior coverage with hyperlipidemia (OR = 1.67, 95% CI: 1.35 – 2.07), diabetes (OR = 2.36, 95% CI: 1.81 – 3.08), and hypertension (OR = 2.09, 95% CI: 1.82 – 2.4) | — |
| Zhang et al. (2011) | Pennsylvania beneficiaries ≥65 with hypertension and continuous coverage from a single health insurer; coverage types included: (1) no‐gap coverage, (2) $150 cap, and (3) $350 cap, compared to those with employer‐sponsored coverage without a coverage gap (N = 16,002) | Administrative (pharmacy claims and enrollment data), 2004–2007 | Relative to the changes in the comparison group, those without prior drug coverage had the largest increase in use of antihypertensive medications (likelihood of use, OR = 1.40, 95% CI: 1.25–1.56; number of pills per day, 0.29, 95% CI: 0.24–0.33) | — |
| Zhang, Lee, and Donohue (2010c) | Pennsylvania beneficiaries ≥65 with: (1) no‐gap coverage, (2) $150 cap, and (3) $350 cap who then received Medicare Advantage in 2006, compared to enrollees with stable drug coverage and no caps (N = 35,102) | Administrative (insurance claims), 2004–2007 | Largest increase in antibiotic use among those without prior drug coverage (OR = 1.58, 95% CI: 1.36–1.85); largest increases in antibiotic subclasses of quinolones (OR = 1.70, 95% CI: 1.35–2.15) especially among those without prior drug coverage and with $150‐caps; pneumonia‐related ambulatory antibiotic use increased (OR = 3.60, 95% CI: 2.35–5.53) more than use associated with other acute respiratory tract infections (OR = 2.29, 95% CI: 1.85–2.83) | — |
| Repeated cross‐sectional | ||||
| Blumberg et al. (2015) | Beneficiaries with glaucoma before Part D, compared to after Part D (N = 20,688) | Survey and administrative (Medicare Current Beneficiary Survey and Medicare claims), from 2004 to 2009 | Cost‐related nonadherence declined (taking smaller doses: 9.4% vs. 2.7%, p < .001; skipping doses due to cost: 8.2% vs. 2.8%, p < .001) | — |
| Hanlon et al. (2013) | Black and white Medicare beneficiaries ≥70 years with coronary heart disease and/or diabetes mellitus, post–Part D; compared pre–Part D (N = 1,091) | Survey (Health Aging and Body Composition Study), 2002–2008 | Prior to Part D, blacks were less likely to take an antilipemic (32.7% vs. 49.4%); antilpemics use increased after Part D (blacks 48.3%, whites 64.6%) | — |
| Cross‐sectional data | ||||
| Gellad et al. (2013) | Part D beneficiaries ≥65 with diabetes, compared to veterans ≥65 with diabetes (N = 1,571,580) | Administrative (Medicare Prescription Drug Event files; Veterans Administration outpatient and prescription claims, and enrollment data), 2008 | Higher brand‐name drug use among Part D beneficiaries (hypoglycemics: 35.3% vs. 12.7%, statins: 50.7% vs. 18.2%, angiotensin‐converting enzyme inhibitors or angiotensin‐receptor blockers: 42.5% vs. 20.8%, insulin analogs: 75.1% vs. 27.0%) | — |
| Stuart et al. (2011) | Diabetic Medicare beneficiaries enrolled in Part D, compared to those in retiree drug subside plans (N = 257,532) | Administrative data (Chronic Condition Warehouse, MarketScan Medicare Supplemental and Coordination of Benefits database), 2006 | Except insulin use (18.8% vs. 17.7%), the treatment group showed lower use of antidiabetic agent (73.7% vs. 75.9%), oral antidiabetic (65.5% vs. 67.4%), renin–angiotensin–aldosterone system inhibitors (66.6% vs. 67.3%), and antihyperlipidemics (60.5% vs. 69.4%) at p < .0001 | — |
| Yazdany, Tonner, and Schmajuk (2015) | Medicare beneficiaries ≥65 using biologic drugs for rheumatoid arthritis without low‐income subsidies (with or without gap coverage), compared to those receiving low‐income subsidies (N = 6,932) | Administrative (claims), 2009 | Beneficiaries with low‐income subsidies more likely to obtain biologics (relative risk ratio = 2.98, 95% CI: 2.50–2.56) | Beneficiaries with low‐income subsidies pay lower OOP costs ($72 vs. $3,751) |