Association of Medicare Part D Medication Out‐of‐Pocket Costs with Utilization of Statin Medications

Abstract

Objectives. To examine the association between statin out-of-pocket (OOP) costs and utilization among the Medicare Part D population. Data Sources/Study Setting. 2006-2008 administrative claims and enrollment data for the 5 percent Medicare sample. Study Design. Sample included 346,583 beneficiary-year observations of statin users enrolled in stand-alone prescription drug plans, excluding low-income subsidy recipients. We estimated the association between a plan's OOP statin costs and statin utilization using an instrumental variable approach to account for potential bias due to plan selection. Adherence was defined as percentage of days covered (PDC) of at least 80 percent. Plan OOP costs were constructed for a representative market basket of statin medications. Analyses controlled for demographic characteristics, cardiovascular disease risk, co-morbidity presence, and regional characteristics. Principal Findings. About 67 percent of the sample had a PDC of at least 80 percent. An increase in annual statin OOP from $200 (50th percentile) to $240 (75th percentile) was associated with a reduction in the rate of adherent beneficiaries from 67 percent to 56 percent (p < .001). Conclusions. Greater OOP costs for statins are associated with reductions in statin utilization.

Access to Oral Osteoporosis Drugs Among Female Medicare Part D Beneficiaries

“…Consistent with prior research (Karaca-Mandic et al, 2012a; Karaca-Mandic et al, 2012b, Karaca-Mandic et al, 2010; Goldman et al, 2004), plan OOP drug costs were computed for each beneficiary not receiving any low-income-subsidy (LIS) by calculating the average monthly OOP cost for a representative, fixed basket of oral osteoporosis drugs separately for 2007 and 2008 (Karaca-Mandic et al, 2012a; Karaca-Mandic et al, 2012b, Karaca-Mandic et al, 2010). The Part D Denominator Files, Prescription Drug Event Files, and Plan Characteristics Files allowed us to identify beneficiaries’ enrollment in specific drug plans, their initiation of oral osteoporosis medications, and their plan’s cost-sharing information during the pre-initial coverage limit (pre-ICL) and donut (gap) phases respectively.…”

“…Among patients who start medication therapy, low adherence rates and high discontinuation rates are common (Brookhart et al, 2007; Weycker et al, 2006; Solomon et al, 2005). In general, higher pharmacy cost sharing is associated with the use of fewer medications especially among older adults (Harris, Stergachis, & Reid, 1990; Smith, 1993; Lillard, Rogowski, & Kington, 1999; Joyce, Escarce, Solomon, & Goldman, 2002; Goldman et al, 2004; Goldman, Joyce, & Zheng, 2007; Karaca-Mandic, Swenson, Abraham, & Kane, 2012a). While Medicare Part D has increased beneficiaries’ access to prescription drugs (Licthenberg & Sun, 2007), there are significant differences in drug plans’ cost-sharing (Karaca-Mandic et al, 2012a), tiered formulary structures (Hoadley, Hargrave, Merrell, Cubanski, & Neuman, 2007), number of covered drugs (Hoadley, Hargrave, Merrell, Cubanski, & Neuman, 2008), and provision of gap coverage (Hoadley, Cubanski, Hargrave, Summer, & Neuman, 2009).…”

“…In general, higher pharmacy cost sharing is associated with the use of fewer medications especially among older adults (Harris, Stergachis, & Reid, 1990; Smith, 1993; Lillard, Rogowski, & Kington, 1999; Joyce, Escarce, Solomon, & Goldman, 2002; Goldman et al, 2004; Goldman, Joyce, & Zheng, 2007; Karaca-Mandic, Swenson, Abraham, & Kane, 2012a). While Medicare Part D has increased beneficiaries’ access to prescription drugs (Licthenberg & Sun, 2007), there are significant differences in drug plans’ cost-sharing (Karaca-Mandic et al, 2012a), tiered formulary structures (Hoadley, Hargrave, Merrell, Cubanski, & Neuman, 2007), number of covered drugs (Hoadley, Hargrave, Merrell, Cubanski, & Neuman, 2008), and provision of gap coverage (Hoadley, Cubanski, Hargrave, Summer, & Neuman, 2009). Concerns have also been raised about the adverse effect of the donut hole on medication use (Zhang, Donohue, Newhouse, & Lave, 2009; Raebel, Delate, Ellis, & Bayliss, 2008; Fung et al, 2010; Hsu et al, 2008; Gu, Zeng, Patel, & Tripoli, 2010; Hales & George, 2010).…”

Medication Nonadherence: The Role of Cost, Community, and Individual Factors

“…; Karaca‐Mandic et al. ; Rezayatmand, Pavlova, and Groot ), individual‐level characteristics including demographic, socioeconomic, and psychological factors (Cummings et al. ; Lewey et al.…”

“…Past research has examined the challenges of medication adherence across numerous contexts, including specific chronic diseases (Cramer 2004), multiple chronic conditions (Williams, Manias, and Walker 2008), and cost-and medication-related factors (Claxton, Cramer, and Pierce 2001;Gellad, Grenard, and Marcum 2011). Researchers have documented the influence of several factors on medication adherence, such as higher cost sharing and OOP expenses (Leibowitz, Manning, and Newhouse 1985;Joyce et al 2002;Goldman, Joyce, and Karaca-Mandic 2006;Goldman, Joyce, and Zheng 2007;Gibson et al 2010;Karaca-Mandic et al 2012;Rezayatmand, Pavlova, and Groot 2013), individual-level characteristics including demographic, socioeconomic, and psychological factors (Cummings et al 1982;Lewey et al 2013;Rolnick et al 2013), and health care system factors (Schmittdiel et al 2011). Although scholars have synthesized findings using meta-analyses, there remains a lack of consensus across the factors heavily influencing medication adherence (Eaddy et al 2012;Conn et al 2014;Murphy et al 2014).…”