Cost Sharing and Decreased Branded Oral Anti-Diabetic Medication Adherence Among Elderly Part D Medicare Beneficiaries

Abstract

BACKGROUND:Although the Medicare Part D coverage gap phase-out should reduce cost-related nonadherence (CRN) among seniors with diabetes, preferential generic prescribing may have already decreased CRN, while smaller numbers of patients using more costly branded oral antidiabetic (OAD) medications remain vulnerable to CRN. OBJECTIVE: To estimate the effects of cost sharing in the Part D standard (non-LIS) benefit on adherence to different OAD classes, comparing two classes dominated by inexpensive generic medications and two by more costly branded medications. DESIGN AND PATIENTS: Retrospective cohort study using dispensed prescription data for elderly non-LIS (N= 81,047) and LIS (low-income subsidy) (N=150,359) beneficiaries using same class OAD(s) in 2008 and 2009. Logistic regression modeled non-LIS likelihood; LIS and non-LIS patients matched using propensity outcome (N= 38,054). Logistic regression, controlling for demographic and health status characteristics, modeled effects of non-LIS coverage on 2009 OAD class adherence. MAIN MEASURES: Main outcome measures were within-class OAD coverage year adherence, with patients considered adherent when days supplied to calendar days ratio at least 0.8. KEY RESULTS: Non-LIS patients had 0.52 and 0.57 times the odds of branded-only DPP-4 Inhibitor (N= 1,812; 95 % CI: 0.43, 0.63; P<0.001) and Thiazolidinedione (TZD) (N=6,290; 95 % CI: 0.52, 0.63; P<0.001) adherence. Most patients (N=32,510; 82 %) used OADs in primarily generic classes, where we found no significant (Biguanides; N=21,377) or small differences (Sulfonylureas/Glinides [N=19,240; OR: 0.91; 95 % CI: 0.86, 0.97; P =0.002]) in adherence odds. Crude adherence rates were sub-optimal when CRN was not a factor (Non-LIS/LIS: Biguanides: 65 %/65 %; Sulfonylureas/Glinides: 66 %/ 68 %; LIS: DPP-4 Inhibitors: 66 %; TZDs: 67 %). CONCLUSIONS: Gap elimination would not affect generic, but should reduce branded OAD CRN. Branded copayments may continue to lead to CRN. Policy initiatives and benefit changes targeting both cost deterrents for patients with more complex disease and non-cost generic OAD underuse are recommended.

Medicare Part D Prescription Drug Program: Benefits, Unintended Consequences and Impact on Health Disparities

“…2 Among the generic oral anti-diabetic medications, they find small or no significant difference in adherence odds by low-income supplement status, though they do find that crude adherence rates are sub-optimal when cost-related non-adherence is not a factor. 2 They conclude that the Affordable Care Act policy of 2010 to close the Medicare gap by 2020 1 will not affect generic oral anti-diabetic medication adherence but should reduce costrelated non-adherence in branded oral anti-diabetic medications. 2 However, they also express concern that prior to gap closure, co-payments on the branded oral anti-diabetic medications may continue to lead to cost-related non-adherence.…”

“…In this issue of the journal, Sacks et al 2 examine the effects of cost sharing in the Medicare Part D standard (non-low income supplement) benefit on adherence to different oral anti-diabetic classes of medications. They find that non-low income supplement beneficiaries have higher odds of adherence to brand medications.…”

“…They find that non-low income supplement beneficiaries have higher odds of adherence to brand medications. 2 They also find that 82 % of all beneficiaries use oral anti-diabetics in primarily generic classes. 2 Among the generic oral anti-diabetic medications, they find small or no significant difference in adherence odds by low-income supplement status, though they do find that crude adherence rates are sub-optimal when cost-related non-adherence is not a factor.…”

“…2 They also find that 82 % of all beneficiaries use oral anti-diabetics in primarily generic classes. 2 Among the generic oral anti-diabetic medications, they find small or no significant difference in adherence odds by low-income supplement status, though they do find that crude adherence rates are sub-optimal when cost-related non-adherence is not a factor. 2 They conclude that the Affordable Care Act policy of 2010 to close the Medicare gap by 2020 1 will not affect generic oral anti-diabetic medication adherence but should reduce costrelated non-adherence in branded oral anti-diabetic medications.…”

“…2 They conclude that the Affordable Care Act policy of 2010 to close the Medicare gap by 2020 1 will not affect generic oral anti-diabetic medication adherence but should reduce costrelated non-adherence in branded oral anti-diabetic medications. 2 However, they also express concern that prior to gap closure, co-payments on the branded oral anti-diabetic medications may continue to lead to cost-related non-adherence. 2 The authors recommend modifications to the Part D benefit structure to remove cost-related adherence deterrents, as well as initiatives to address non-cost factors in adherence to the less expensive generic oral anti-diabetic medications.…”