In this study, we used the most recent national data to explore material, psychological, and behavioral domains of medical financial hardship in the USA and found that 137.1 million adults reported any medical financial hardship in the past year. Among adults aged 18–64 years, more than half reported at least one and about one-fourth reported at least two domains of financial hardship. Hardship and its relative intensity were significantly lower in the older group, despite higher prevalence of multiple chronic conditions and lower household income,21 illustrating the protective effects of Medicare coverage. Even so, more than one-third of those aged ≥ 65 years reported at least one domain of hardship. With recent trends towards increasing prevalence of multiple chronic conditions,22 higher patient cost-sharing,23 and increasing costs of health care24, the risks of financial hardship will likely increase in the future. Thus, unless addressed, medical financial hardship may become an increasingly common consequence of illness in adults of all ages. Research addressing aspects of medical financial hardship is increasing in other countries,25,26,27,28 and in older studies, adults in the USA have higher OOP spending on health care than in European countries.27, 28 Our findings are not directly comparable to those in other countries because of important differences in measures of financial hardship and health system features, as well as study populations. Understanding the role of health care system features in development of medical financial hardship and adverse health outcomes will be important for future research.

We found striking differences in financial hardship by type of health insurance coverage—more than three-fourths of the uninsured aged 18–64 years reported any hardship and more than half reported multiple domains of hardship. In contrast, closer to one-fourth of those aged 18–64 years with private insurance coverage reported multiple domains of hardship. Because the uninsured have historically experienced worse access to care and poorer health outcomes,29 addressing medical financial hardship will be especially important for this group, to minimize the risk of widening health disparities. In addition, with more than 40% of working age adults aged 18–64 years receiving coverage through high-deductible health insurance plans30, 31 and greater cost-sharing among the insured,32 health insurance coverage alone may be insufficient to fully protect the privately insured from medical financial hardship.

We also found that receipt of prescription drugs in the past year was associated with all domains of financial hardship, even after controlling for the effects of health conditions and sociodemographic factors. Others have shown that high OOP spending on prescription drugs plays an important role in financial hardship,33 even for those with private health insurance coverage. Increasingly, drugs for conditions such as cancer, rheumatoid arthritis, and multiple sclerosis have annual list prices of > $100,000. With coinsurance of ≥ 20% for specialty drugs,23 patients can face ≥ $20,000 in OOP costs annually, which also has implications for health outcomes. High OOP costs are strongly associated with cost-related medication non-adherence,33, 34 and non-adherence is associated with greater risk of emergency room visits,35 preventable hospitalizations,36 and death.36 Other components of health care, such as advanced imaging and novel surgical techniques, may also play a role in rising patient OOP costs. Evaluation of the role of prescription drugs and other components of health care in financial hardship and related effects on health outcomes will be an important area for additional research using longitudinal study designs.

Lower educational attainment was associated with greater medical financial hardship intensity in both age groups. These findings are consistent with other studies evaluating financial hardship37 and access to care.38 In addition to being a measure of socioeconomic position, educational attainment may reflect health literacy and health insurance literacy, factors independently associated with access to care.39, 40 With complex and continuously changing health insurance system(s), patient health insurance literacy is increasingly receiving attention in the USA,41,42,43 especially because it is potentially modifiable by intervention.43,44,45,46

In recognition of adverse health consequences of financial hardship, a number of patient-level intervention strategies have been developed to reduce its impact, including educational programs aimed at improving health insurance literacy, screening tools, financial navigation linking patients to community resources.47 Other efforts have focused on enhancing patient-provider discussions about expected costs and benefits of care.48, 49 Insurer-level strategies, such as the value-based insurance design (VBID), which focus on providing high-quality rather than high-volume care, are associated with reduced patient OOP costs in some settings.50 To date, however, VBID for prescription drugs has generally focused on specific drug classes or generic substitution and rarely addresses OOP costs for specialty drugs or for drugs without generic substitutes. Little research has reported effects of value-based episodes of care or bundled payment models on patient OOP costs or financial hardship. Development and evaluation of interventions to minimize financial hardship and adverse health outcomes at the patient, provider, and insurer levels are ongoing.

State-level Medicaid eligibility expansions as part of the implementation of the Affordable Care Act are associated with increased health insurance coverage,51, 52access to care,52, 53 and reduced financial strain53 and worry about paying bills52 in low-income adult populations ≤ 64 years, but not all states have expanded eligibility for Medicaid coverage. Even in states that did expand Medicaid eligibility, some low-income individuals remain uninsured and many of the insured face challenges with health care affordability. Other state-level policies, such as those addressing price transparency,54, 55 surprise medical bills,56 generic drug substitution by pharmacists,55 and requirements for some employers to offer employees paid sick leave57 could reduce the risk of medical financial hardship, but to date, little research has been conducted to evaluate their impact. Evaluating the effects of state and federal health policies on patient OOP and financial hardship will be important for future research.

Despite the strengths of the most recent population-based nationally representative data to explore multiple domains of financial hardship, this study is subject to bias introduced by self-reported measures. Medical record data were not available from the NHIS and the NHIS did not include detailed questions about the underlying cause of different aspects of medical financial hardship. Further, questions were not specific about the health effects resulting directly from financial hardship, including health-related quality of life. Data were cross-sectional and we could not evaluate long-term health implications of hardship, nor do our findings provide specific details for intervention development. Nonetheless, the fact that many Americans are having trouble paying medical bills, experiencing significant distress, and delaying or forgoing care due to cost is important information for patients, health care providers, health plans, and policy makers. Improving understanding and measurement of medical financial hardship and developing and evaluating effective interventions to reduce its risk will be important for future research.

In summary, medical financial hardship is common among adults in the USA, with nearly 140 million adults reporting hardship in the past year. Among those aged 18–64 years, more than half report problems with medical bills or medical debt; stress or worry; or forgoing or delaying health care due to cost. The highest prevalence and greatest intensity of medical financial hardship are among the uninsured. With increasing prevalence of multiple chronic conditions,22 higher patient cost-sharing,23 and higher costs of health care,24 the risk of hardship will likely increase in the future. Thus, development and evaluation of the comparative effectiveness and cost-effectiveness of strategies to minimize medical financial hardship will be important.