Cost-related medication nonadherence in adults with COPD in the United States 2013–2020

Chronic obstructive pulmonary disease (COPD) is a persistent and progressive airway disease characterized by difficulty in breathing, coughing, and sputum production [1‐4]. According to the World Health Organization (WHO), COPD is the third leading cause of chronic morbidity and mortality worldwide, including in the US and China [3, 5‐8]. In 2017, the estimated number of people living with chronic respiratory diseases worldwide was at 544 million, with approximately 55% of cases attributable to COPD [4, 7].

The Global Initiative on Obstructive Lung Disease (GOLD) recommends that patients with COPD should undergo long-term therapy to improve prognosis, particularly through medication adherence [9, 10]. However, long-term medication adherence in patients with COPD is poor, which is less than 50% according to the WHO reports [11, 12]. Increasing medication nonadherence is associated with increasing COPD symptoms, morbidity, hospitalizations, mortality, and healthcare expenditures [11, 13, 14]. Although medication nonadherence is complex and multifactorial, cost-related medication nonadherence (CRN) is modifiable. Effective drug management has been shown to reduce the financial burden on and improve the clinical characteristics and prognosis of patients [15].

Although previous studies have reported poor long-term medication adherence among patients with COPD, recent data on the prevalence of this issue are lacking. Moreover, there is a paucity of studies about CRN in US COPD patients. Furthermore, previous study had demonstrated that economic disparities and inadequate insurance coverage negatively impact healthcare for individuals with COPD [16]. However, despite efforts such as the Affordable Care Act (ACA), these challenges have not been adequately addressed [16]. Despite expanded insurance coverage, escalating prescription drug costs have resulted in no improvement or even a decline in the affordability of care for individuals with COPD [14, 16]. Therefore, improving medication adherence and health outcomes in patients with COPD remains an urgent and elusive challenge for the global health community [3]. In this study, we used nationally representative data to investigate the prevalence and sociodemographic characteristics of CRN among adults with COPD in the US to provide healthcare systems with recommendations for health interventions to improve patient outcomes and enhance the quality of life of patients with COPD.

Of the 253,577 US adults included in the NHIS from 2013 to 2020, 17,591 reported COPD. This corresponds to 5.9% of US adults, representing an estimated 14.38 million patients per year (95% confidence interval [CI] 14.02–14.78 million). Of the 17,591 adults with COPD, 15,928 (90.54%) completed the individual components for CRN, and 2881 self-reported experience of CRN. This equates to an average of 2.39 million (95% CI 2.28–2.51 million; 18.56%) US adults with COPD reporting CRN each year from 2013 to 2020 (Supplemental Fig. 1).

In this nationally representative study conducted in the US using the most updated NHIS data (2013–2020), we found that nearly one in six individuals with COPD, which equates to 2.39 million adults, was nonadherent with their medications due to medication costs. The prevalence of CRN was higher among younger individuals, women, low-income families, uninsured, and greater morbidity burden, which is consistent with previous reports [23].

Overall, from 2013 to 2020, the rate of reported CRN in patients with COPD had a declining pattern, from 22.03% in 2013 to 14.57% in 2020, likely because of the enactment and implementation of the Patient Protection and ACA in 2014 in the United States, which was designed to increase health insurance coverage and provide low-income populations with making financial subsidies to reduce individual health care costs [16, 24].

Furthermore, our study demonstrated a significant difference in the prevalence of CRN between the < 65 years and ≥ 65 years age groups of individuals with COPD. Although individuals with COPD aged < 65 years were more likely to have fewer comorbidities than those aged ≥65 years, they were twice as likely to not adhere to medication. There are multiple factors contributing to CRN among COPD patients aged < 65 years and ≥ 65 years, encompassing economic aspects such as insurance and drug costs, as well as patient behavior and perception factors [25‐28]. The absence of insurance may impact patients’ reporting of CRN. Uninsured individuals might postpone or discontinue treatment due to the exorbitant medical expenses associated with COPD management. However, even with medical insurance coverage, CRN can still arise owing to out-of-pocket (OOP) prescription drug costs [29]. Although insurance partially reimburses these expenses, patients are still required to bear a certain amount OOP which could pose a barrier for those facing financial constraints [5, 29]. Furthermore, younger individuals tend to prioritize personal interests and immediate gratification, they may pay more attention to the short-term effects of drugs and ignore the long-term treatment effects [12]. Consequently, when they fail to perceive the benefits of medication clearly, they might opt not to adhere to medical advice owing to the exorbitant cost associated with pharmaceuticals [12]. Additionally, young individuals often exhibit heightened confidence in their physical well-being and self-healing capabilities while harboring reservations regarding the effectiveness of medications, this skepticism might impact their adherence [12].

Our study revealed that individuals with low household income were more likely to report CRN. In 2016, the total spending on all respiratory illnesses in the US was $170.8 billion, which has increased by $71.7 billion since 1996. In the same year, the respiratory condition with the highest spending was COPD, contributing $34.3 billion [30]. The debilitating properties of COPD, a highly prevalent respiratory disease, place a significant financial burden on the US healthcare system [3, 31]. Furthermore, OOP prescription medication costs are increasing, and are a major factor influencing medication nonadherence [28, 29, 32, 33], and growing prescription drug spending is straining the finances of governments and patients. It is well known that inhaled drug therapy is the basic method of COPD treatment, and long-term adherence to inhaled drug therapy has been shown to improve COPD outcomes [6]. However, inhalers are more expensive than many other commonly prescribed drugs [33, 34], missing or delaying medication because of financial concerns has become increasingly common [35, 36]. In addition, the US Food and Drug Administration (FDA) banned the production and sale of all Chlorofluorocarbon (CFC) based salbutamol inhalers in 2008 to reduce environmental pollutants, but were thus replaced by more expensive hydroflurane inhalers [37]. Because exclusivity protections extend the life of branded therapies, patient drug costs are affected by prices set by manufacturers, which drives OOP costs higher for patients, especially those with private insurance [38]. This increase in cost could reduce the affordability of prescribing programs and thus reduce patient nonadherence [38]. Therefore, costs associated with COPD medication are an increasing concern, and introducing public health interventions that address barriers to this burden to reduce the incidence of CRN is imperative [29].

We also found that CRN in patients with COPD was different concerning sex. In this study, among adults with COPD who reported CRN, 68% were female, women had a nearly 50% higher risk of CRN compared to men. Sex has been identified as a factor significantly associated with CRN in a wide range of medical care [3, 39] suggesting that sex influences CRN in patients with COPD. The challenges to pay for medical care experienced by men and women may be different and need to be considered when developing interventions.

Patients with COPD often have comorbidities [40]. There were significant differences in CRN between patients with and without certain comorbidities. As reported in previous studies, we found that patients with certain comorbidities had a significantly higher risk of CRN than patients without these comorbidities [40]. Complex medication regimens, polypharmacy, the route of administration, and expensive drug cost are common and important contributors to suboptimal medication adherence among patients with certain comorbidities [12, 40]. Patients taking multiple medications, each with a different dosing pattern, are often frustrated and confused by the complex dosing regimens and the high cost of the medication, causing them to miss some doses [13]. Errors in employing inhalation techniques are common among patients using inhaled medications [3, 11, 41]. This case is unique in that if the administration technique is inaccurate, the medication will not be delivered to the lower respiratory tract of the patients, resulting in unnecessary cost waste [42]. Similarly, in some healthcare systems, the inability to pay for or reduced access to medication is associated with non-adherence. These results reinforce the importance of observing the medical and social challenges faced by patients with certain comorbidities to reduce CRN.

CRN is a major risk factor for therapeutic effects in the clinical treatment of patients. High rates of CRN warrant a broader focus on decreasing drug costs and improving health insurance coverage. Although our study provided a reference for the characteristics and risk factors of nonadherence, it has a few limitations. First, as this study was conducted in the US, our results may not be generalizable to other countries where insurance coverage, drug prices, and drug affordability differ. Second, COPD diagnosis was based on self-report, however, the rate of self-reported COPD in the NHIS dataset is consistent with the national rate of diagnosed COPD reported by the National Centre for Health Statistics [43]. Finally, due to the limitations of the database utilized in this study, several risk factors were not included the database, including disease severity in COPD patients, patient beliefs and experiences, as well as behaviors such as oral/inhaled medication usage and number of medications taken. The extent to which these risk factors affect CRN reported by patients with COPD could not be ascertained. And we did not capture the relationship between negative emotions, such as depression, and CRN in the study. However, some previous studies have found that depression was associated with medication nonadherence [3, 40]. The issue of the effect of negative emotions and CRN is an avenue for future research.

In the US, one in six adults with COPD reported CRN. The influencing factors of CRN are multifaceted and necessitating more rigorous research. Health policy interventions focusing on reducing drug costs, delaying disease progression, preventing exacerbations, and reducing the risk of comorbidities may improve the economic burden of COPD and its outcomes. This report can serve as an reference for improving medication nonadherence.