Addressing disparities in diagnosing cystic fibrosis in diverse populations

Key takeaways:

• Physicians were previously under the impression that only white individuals could get cystic fibrosis.
• Clinical trials studying cystic fibrosis triple therapy were mostly made up of white individuals.

WASHINGTON — For people with skin of color, a diagnosis of cystic fibrosis is often delayed or missed, and they are not well represented in treatment trials, according to an American Thoracic Society International Conference presentation.

“Racism does occur in medicine,” Jennifer L. Taylor-Cousar, MD, MSCS, ATSF, professor of medicine and pediatrics at National Jewish Health and University of Colorado Anschutz Medical Campus, said during the presentation. “Even though race and ethnicity are social constructs, because of racism, which impact the social determinants of health, we therefore see the effects in medicine.”

According to Taylor-Cousar, CF was initially described as a disease that widely impacted different races and regions, but when it was described in textbooks, it was classified as a disease that only affects white individuals. From that point forward, this inaccuracy has been perpetuated.

“That has led to misdiagnosis, late diagnosis and decreased health outcomes for people of color,” Taylor-Cousar said.

Despite this ongoing mischaracterization of who can get CF, Taylor-Cousar said the disease is now starting to be acknowledged as something that can manifest in any race/ethnicity. Notably, some areas, such as those in South Africa, are only now diagnosing people with CF.

However, even with this understanding, this diagnosis may still be missed or difficult to make due to the fact that the most common CF variant, F508del, is specific to those of European ancestry, Taylor-Cousar said. Further, only two of the top 25 most common CFTR variants in the U.S. are mutations that are often found in Black patients.

“If you create your tests based on that list, you’re going to miss most of the people who are Black,” Taylor-Cousar said.

Newborn screening

Early diagnosis of CF is known to contribute to better outcomes; however, newborn screening for CF differs by state, which can contribute to disparities, Taylor-Cousar said.

To demonstrate the prevalence of racial disparities, she spoke about a study by Meghan E. McGarry, MD, MAS, and colleagues, on which Healio has previously reported. From this study, Taylor-Cousar highlighted that 3.6% of newborns with CF were Black/African American, and the percentage of false negative screening was 6.5% in this patient group.

She went on to say that because of the long-told myth that only white individuals get CF, only white patients and their common F508del variant have been studied, leaving the variants frequently found in Black individuals unexplained.

“That's the systemic bias that’s gone into medicine that’s created these disparities,” Taylor-Cousar said. “We can fix them by changing our tests.”

Even after a newborn receives positive screening results, racial disparities are present, with one study observing a delayed time from screening to first CF center evaluation in infants with skin of color compared with white infants.

Further, delays in diagnosing CF are not only found in newborns, but in adults. Taylor-Cousar said this diagnosis is often delayed in Black adults since many physicians do not believe this disease is an option for them.

Clinical trials

Importantly, this disparity extends into clinical trials, with only 4.1% of Hispanic individuals, 1.2% of Black individuals, 0% of Asian individuals and 0% of Indigenous individuals included in phase 3 trials of elexacaftor/tezacaftor/ivacaftor (Trikafta, Vertex Pharmaceuticals), Taylor-Cousar said.

“Black and Hispanic people were excluded from that opportunity [of getting access to the CF drug in an open label fashion] because their variants hadn’t been studied, and therefore they weren’t included in these trials,” she said.

She went on to say that this lack of representation in clinical trials translates into inequitable access to CFTR modulator therapy. Data from a study using the CF Foundation's patient registry demonstrated that only 76% of Hispanic individuals and 70% of Black individuals were eligible for a CFTR modulator compared with 92% of white individuals.

“People who are already at a disadvantage from being late diagnosed, misdiagnosed and having bias in medicine that leads to poor health outcomes also are less eligible for these highly effective therapies, widening that gap even further,” Taylor-Cousar said.

“To improve diagnosis and outcome in people of color, we must address both the systemic and individual bias that drives these health inequities,” she concluded.