Despite a fall in the number of people with asthma over the past decade who say that cost has stopped them taking their meds as prescribed, financial hardship still remains a deterrent for one in six with the condition, suggests research published online in the journal Thorax.

Failure to stick to their drug treatment was associated with a near doubling in the risk of an asthma attack and a more than 60% heightened risk of an emergency department visit, the findings indicate.

The findings reinforce the importance of health care policy in promoting equitable access to drug treatment, concludes a linked editorial.

In 2021, the Centers for Disease Control and Prevention estimated that around 20 million adults (8%) had asthma in the US. Although the condition can be well controlled with medication, the prevalence of non-adherence to treatment is high, note the researchers.

To find out what factors might be driving this among patients with asthma, the researchers drew on the survey responses of 30,793 adults with the condition (about 8% or 19.38 million of the US population), to the nationally representative annual National Health Interview Survey (NHIS) from 2011 to 2022.

Survey respondents were asked if, over the past 12 months, they had skipped medication doses; or taken fewer doses; or delayed repeating their prescriptions to save money. Answering yes to any of these questions was defined as not sticking to their treatment regimen as prescribed because of its cost.

Respondents were also asked if, over the past 12 months: they had had an episode of asthma/asthma attack; or had had to visit emergency care or an urgent care center because of their asthma.

Overall, 18% of survey respondents with asthma said they couldn't afford to take their meds as prescribed, equivalent to just short of 3 million of the US population with the condition.

To save money, 12% (1.95 million equivalent) of respondents said they skipped medication doses; 12.5% (2.06 million equivalent) said they took fewer doses; and 15% (2.54 million equivalent) said they delayed repeating their prescription.

The proportion citing cost as a reason for not sticking to their treatment regimen fell significantly during the 12-year period, from 23% in 2011 to 13% in 2022. But that still left the equivalent of one in six adults with asthma citing financial hardship as the reason for not taking their meds as prescribed in 2022.

Those aged 18–60, women, and Black people were more likely to report not taking their meds as prescribed because of the expense. Other influential factors included living in Southern US states, low educational attainment, lack of health insurance, low household income, co-existing conditions, and living alone.

Those citing financial hardship had nearly double the odds of an asthma attack and a more than 60% heightened risk of visiting emergency care than those for whom cost wasn't a factor.

This is an observational study, and as such, no firm conclusions can be drawn about cause and effect. The researchers also acknowledge that their study relied on subjective assessment rather than on diagnostic tests and medical records, and they weren't able to evaluate the potential impact of asthma severity on medicine compliance either.

They suggest that the falling trend in people citing cost as a reason not to take their meds as prescribed might be due to the introduction of the Patient Protection and Affordable Care Act in 2010, which aimed to improve access to health insurance and services, and the expansion of Medicaid in 2014.

"With fewer barriers to accessing health care, including medications, patients may be more willing to fill prescriptions for medications to control their asthma than before," they suggest.

In a linked editorial, Emily Graul and Dr. Christer Janson of, respectively, Emory University School of Medicine, Atlanta, and the Department of Medical Sciences, Uppsala University, Sweden, point out that asthma meds make up around half of the total spend on the condition.

"Therefore, efforts to reduce cost-related medication non-adherence not only lessen the financial burden on the US health system but also support people's ability to improve their disease symptoms," they suggest, adding that continued policy and legislation efforts are needed to ensure this happens.

"The Inflation Reduction Act's associated Medicare Drug Price Negotiation Program lowered drug costs for several chronic conditions, but so far this has not included drugs for respiratory conditions, including asthma despite their high gross annual spending.

"The results of this study beg the question: should certain asthma medications be part of the next batch of drug negotiations?"