The Prevalence and Predictors of Low-Cost Generic Program Use in the Pediatric Population

Low-cost generic drug programs (LCGPs) first appeared in the USA in mid-2006, with Kmart providing 90 days of certain generics for $US15; this was shortly followed by Wal-Mart’s $US4 program [1]. Generic discount programs are now in place at almost all major pharmacy chains, including eight of the top ten largest chain pharmacies in the nation, and include one-third of the top 100 generics used by Americans by volume [1‐3]. Medications available through LCGPs can be used to treat many common medical conditions experienced by children, including infections, asthma, allergies, and digestive disorders [4‐6].

LCGPs have increased the accessibility and affordability of medications, especially for Americans living in poverty or without prescription insurance [2]. Given the low costs of these medications, it is often cheaper for individuals to purchase prescription medications out of pocket via LCGPs than to pay the $US10–20 copay to receive medication through a prescription benefit [2, 7]. A 2011 study estimated potential savings from individuals purchasing medications through LCGPs instead of their insurance programs and determined that Americans could have saved over $US1 billion in 2007 alone [8].

Despite this potential for tremendous cost savings, there is a relative dearth of literature assessing the prevalence of LCGP use in a nationally representative population. In 2008, over 70 million Americans were estimated to have used an LCGP to obtain a prescription medication—a figure that has likely expanded as the number and popularity of these programs has increased [1, 6, 9]. In a 2008 self-reported survey, one-third of adults and one-quarter of children without insurance coverage reported using these programs, and parents reported use of these programs for 14–23 % of children with private or public insurance [9]. However, given that self-reported surveys are particularly prone to recall and selection bias, it is difficult to ascertain whether these estimates accurately represent LCGP use in the pediatric and adolescent populations.

Use of LCGPs has important ramifications for health services research reliant on administrative claims data. Medication paid for out of pocket is a known source of medication exposure misclassification in administrative claims, and LCGPs are a common source of out-of-pocket payments [2, 7]. When individuals fill a medication through an LCGP, the dispensing pharmacist has no incentive to file a claim for the medication with the individual’s insurer, meaning the medication use will be unobserved in the pharmaceutical claims data. If children with different forms of insurance—e.g., public, private, or uninsured—use LCGPs at different rates, it may lead to exposure misclassification in administrative claims sources. Given the expansion of insurance coverage under the Affordable Care Act (ACA), it is more important than ever to estimate how often individuals with different forms of insurance use LCGPs and how this use may impact the potential for differential exposure misclassification in claims data [10].

Few studies have assessed the demographic and clinical characteristics of LCGP users and non-users, and none to our knowledge have assessed LCGP use specifically in a pediatric population. Understanding the factors that influence which individuals currently utilize these programs is a crucial first step in increasing use amongst patients that have the most to gain from LCGPs and quantifying the potential effects that LCGP use may have on the healthcare system. This cross-sectional study had four objectives: (1) estimate the prevalence and predictors of LCGP use in a nationally representative pediatric population; (2) analyze trends amongst children in LCGP use since they were implemented in 2006; (3) determine which medications are most commonly purchased for children through LCGPs; and (4) assess the potential for exposure misclassification due to LCGP use.

Our study found that nearly one in four people aged <18 years who used prescription drugs filled at least one medication through an LCGP during a 2-year period. Of all fills for medications available through LCGPs, 8.6 % were purchased through LCGPs, or 5.7 % of all medications were filled through LCGPs.

No known studies have assessed LCGP medication use in the pediatric and adolescent populations. One survey found that parents reported that their children with no insurance (24 %), public insurance (23 %), and private insurance (14 %) were using low-cost generics [9]. However, this survey did not investigate specific medication use in this population or consider other subject characteristics. Our study used data collected at the pharmacy level, which included specific payment sources, to determine program use. Applying MEPS person weights, we found that 32.0 % of those with private insurance, 19.2 % of those without insurance, and only 9.7 % of those with public insurance used LCGPs (Table 1). In addition to these differences, the overall proportion of users in our study (23.7 %) was slightly higher than the prevalence of use determined in the prior study (18 %) [9].

Children who lack any form of insurance or prescription drug coverage may stand to benefit the most from the inexpensive medications offered through LCGPs. Given the findings that lack of prescription drug coverage is a significant predictor of LCGP use (AOR 3.26 [95 % CI 2.35–4.52]; Table 2), and that nearly one in five uninsured children used an LCGP from 2011 to 2012 (Table 1), it can be seen that this population is indeed using these programs. However, in adjusted analysis, the uninsured pediatric population had roughly 50 % lower odds of using LCGP medications than privately insured children (Table 2). Furthermore, the finding that most LCGP users fall into the two highest income levels suggests that individuals who could benefit most from these programs are not in fact using them as often as they could, suggesting differential access to care among insurance and family income groups [13, 14].

Previous studies have reported cost and access to medications as significant barriers to proper management of pediatric conditions [15‐17]. Inexpensive medications offered through LCGPs improve access to and ameliorate the cost burden of prescription medications for children across the USA. Several findings of this study indicate that LCGPs are commonly being used to assist with the management of both chronic and acute illnesses. Results of this study indicate that rates of LCGP use in the 2011–2012 MEPS panel are markedly higher in children with diseases that can be treated with medications available through LCGPs than the rate in the overall pediatric population (23.7 %). For example, 55.0 % of children with nutritional deficiencies were LCGP users, as well as 47.2 % of those with diabetes, 34.7 % of those with pneumonia, 32.6 % of those with epilepsy, 32.3 % of those with general infections, 31.0 % of those with ear infections, 29.2 % of children with arthritis, and 28.1 % of those with respiratory infections (Table 1).

Despite the benefits of greater LCGP use in the pediatric population, astute researchers must be wary of the potential for exposure misclassification that these programs present when using certain data sources. True medication utilization may not be captured in the administrative claims for individuals who use LCGPs, which may impact the findings of health services research relying on these data sources [18, 19]. Medication use in this age group includes medication classes with significant risk profiles and medications used to treat serious medical conditions. Especially for privately insured children, who according to our findings use LCGPs at a greater rate than publicly insured or uninsured children, exposure misclassification due to LCGP use may circumvent the added protections (i.e., surveillance for drug interactions, etc.) provided by the claims adjudication process. For children with public forms of insurance, exposure misclassification due to LCGP use may have important ramifications on the calculation of quality metrics that Medicaid plans are required to report under the ACA [20, 21]. Using Fig. 2, the potential impact of misclassification can be estimated given that the proportion of fills of each medication class filled through an LCGP provides an estimate of the number of exposures that may go unclassified.

Our study is subject to some limitations. It may remain possible that not all medication use is recorded if all pharmacies used were not surveyed. Our study definition of LCGP use may allow for overestimation of use if only pricing is considered. However, this effect is mitigated by requiring specific quantities supplied for oral medications. Finally, it is possible that some individuals exclusively use pharmacies in which LCGPs are not available and thus this population was never eligible for inclusion in the LCGP user cohort.

This study found a high rate of LCGP users among a nationally representative sample of children and adolescents. Low-cost generics increase the affordability and access to medications where high costs may prohibit treatment. However, considering the implications for patients and the healthcare system as a whole, programs should be implemented so that medication use data are captured and are accounted for in drug policy and pharmacoepidemiological research. Future studies should empirically demonstrate the effects of differential exposure misclassification on the results of claims-based research.