Non-white Canadians with CF face higher risk of death, study finds
Treatment disparities seen in lung transplant, hospitalization rates
Non-white Canadians with cystic fibrosis (CF) have a higher risk of death than white Canadians with the disease, according to a study of nearly 6,000 people with CF.
Despite having similar characteristics at diagnosis and similar rates of CF complications, non-white CF patients also had worse lung function, fewer lung transplants, lower treatment rates, and higher rates of hospitalization.
“There is an urgent need [to] understand why outcomes for Canadians with CF differ between white and non-white individuals,” the researchers wrote in “Disparities in outcomes by race and ethnicity in the Canadian cystic fibrosis population,” published in the Journal of Cystic Fibrosis.
CF is an inherited disorder, in which mutations in the gene that codes for the protein CTFR causes a buildup of unusually thick and sticky mucus in the lungs, pancreas, and other organs. Patients commonly experience lung-related symptoms, like infections, and digestive issues.
CF occurs in people of all races and ethnicities, but is more common in people of white, European ancestry.
Genetic mutations differ
Researchers compared clinical outcomes between white and non-white people with CF from 42 clinics across Canada. In their total sample of 5,990 people with CF, 326 (5.4%) were classified as non-white and 5,593 (93.4 %) were classified as white. The remaining patients had missing race or were listed as unknown race and therefeore excluded from the analysis.
In the non-white CF patient population, 61 were First Nations people, 44 were Black, 33 were South Asian, and 19 were Asian. A large portion of the non-white population, 123 people, was classified as other, and the remaining 36 people were of two or more races.
In their investigation of the genetic mutations causing the disease, the researchers found that a higher percentage, 87.4%, of the white group had at least one F508 deletion, the most common CF-causing mutation. In comparison, 63.2% of the non-white group carried at least one such mutation. A higher proportion (31.3%) of the non-white group was classified in the other genotype group, relative to 10.1% of the white population.
The researchers suggested that “Euro-centric” emphasis on the F508 deletion in clinical care of CF patients may lead to underestimation of disease severity in non-white populations and delay treatment with highly effective modulator therapies.
Characteristics at diagnosis, including age, sex, and impairments in pancreatic function, were similar between the two groups.
In their research investigating racial differences in death rates, the scientists uncovered a 9.3-year survival gap between the two groups. While the median age of survival for the white group was 48.8, the median age of survival for the non-white CF patients was 39.5.
This difference corresponds to a 1.85 times greater risk of death for non-white Canadians with CF.
The non-white group was less likely than the white group to receive a lung transplant. When someone in the non-white group did receive a lung transplant, it was at a younger age than in the white group.
The investigators suggested further research examining if the differing rates of lung transplants were due to systemic barriers to transplants or misconceptions due to factors such as cultural beliefs, cost barriers, or donor compatibility among non-white Canadians with CF.
Lung function calculation
After adjusting for age and year, a race-specific analysis showed that lung function was 4.2% lower for the non-white group. However, when using a different (race-neutral) method of calculation, lung function was 7.4% lower for non-white CF patients.
Given this difference, the researchers expressed concerns about the use of race-specific equations to measure lung function.
“Race-specific reference equations… systemically lead to under-estimation of impairment in Black and Asian individuals,” the team wrote. “As many treatment decisions are based on lung function, underestimation of lung function impairment may contribute to under-treatment and delays in treatment, as individuals may appear to be healthier than they are.”
Hospitalization rates were 1.19 times higher for the non-white group, despite similar odds of CF-related complications (diabetes, depression, and anxiety) and of most bacterial infections.
Treatment differences were also present between groups. While both groups received antibiotics for Pseudomonas aeruginosa infection, the non-white group was more likely to be treated with nebulized, or inhalable, tobramycin and less likely to be treated with TOBI Podhaler, an inhalation powder form of tobramycin.
The non-white group was less likely to receive mucolytic treatment, specifically hypertonic saline aiming to break up mucus and make it easier to cough out of the lungs, and psychiatric medications.
“There is an urgent need to improve equity in outcomes by addressing the modifiable factors contributing to poorer outcomes in racialized Canadians with CF,” the researchers wrote.
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