Worse Lung Function Prevalent in Disadvantaged Neighborhoods
Study underscores effects of race, socioeconomic status on disease outcomes
People with sarcoidosis who live in neighborhoods lacking economic and social resources have lower lung function and faster lung function decline, a study in the U.S. and Canada revealed.
Non-white patients were overrepresented in the group with greater disadvantage, suggesting how race and differences in socioeconomic status can lead to poorer outcomes among people from minority backgrounds. The researchers also emphasized the importance of studying how to reduce neighborhood-level inequalities to ensure better health outcomes in people with sarcoidosis and other chronic diseases.
The study “Neighborhood disadvantage impacts on pulmonary function in patients with sarcoidosis,” was published in ERJ Open Research.
The evidence has shown the economic burden of sarcoidosis can be significant, mainly in vulnerable populations, such as Black people, women, and the elderly, with chronic and persistent disease. Those with sarcoidosis are also known to be affected by low socioeconomic status, particularly as it relates to disease severity and progression, onset of sarcoidosis-related conditions, health-related quality of life, and mortality.
In several chronic respiratory diseases, this burden is higher among those living in neighborhoods of the so-called neighborhood-level disadvantage, which is associated with income, education level, residential and food security, safety, and health behaviors.
Neighborhood-level disadvantage on lung fucntion
The impact of neighborhood-level disadvantage on people with sarcoidosis hasn’t been fully understood, leading researchers to study its effect on lung function in sarcoidosis patients from the U.S. and Canada.
The study included 477 U.S. patients with a median age of 49 at diagnosis from the University of Pittsburgh Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease Registry. The 122 Canadian patients (median age at diagnosis, 52), were from eight Canadian Registry for Pulmonary Fibrosis sites. Median follow-up duration was 8.3 years in the U.S. and 4.1 years in Canada. A total of 15 patients underwent a lung transplant in the U.S., but none in Canada did. Fifty-one patients died in the U.S. And four died in Canada.
About a quarter of the U.S. patients (26%) were non-white — Black, Asian, indigenous or unknown. This population was smaller in Canada at 8%.
Neighborhood-level disadvantage was evaluated by the area deprivation index (ADI) in the U.S. and by the Canadian Index of Multiple Deprivation (CIMD), a similar metric, for Canadian patients. ADI is determined by converting U.S. residential addresses into nine-digit zip codes, which are matched with a U.S. nationwide ADI dataset that’s based on 2018 American Community Survey data. Higher ADI percentile scores reflect greater neighborhood disadvantage.
Lung function parameters included forced vital capacity (FVC), a measure of how much air can be forcibly exhaled in a single breath and diffusing capacity of the lung for carbon monoxide (DLCO), which measures the lungs’ ability to transfer oxygen to the red blood cells in pulmonary capillaries. Patients also were analyzed for extrapulmonary symptoms, treatment with immunosuppressants, age at diagnosis, sex, and race. Other parameters included survival, smoking history and lung transplant status.
Overrepresentation of Black patients
In the U.S. group, participants who were Black were over-represented in the lowest ADI quartile, reflective of greater disadvantage. Only 10 non-whites were present in the Canadian group, which limited a similar analysis.
After adjusting for age at diagnosis, sex and smoking history, U.S. patients who identified as Black or non-white had higher ADI scores. A Black patient had a 13-point higher neighborhood-disadvantage score compared to a white patient. No such association was seen in Canadian patients.
No link was also found between a higher disadvantage level and FVC in both populations after accounting for age at diagnosis, sex, race, and smoking history. In contrast, the highest disadvantage level was associated with a lower DLCO, both in Americans and Canadians.
Results also showed U.S. patients from neighborhoods with greater disadvantage had faster yearly reductions in FVC and DLCO. Compared to patients in the quartile with the least disadvantage, those in the worst ADI quartile had an additional 0.36% decline in FVC and an additional 0.54% decline in DLCO per year.
An increased disadvantage level also was linked to a faster decrease in FVC in the Canadian study population.
The study also found that non-whites were significantly less likely to undergo a lung transplant, which may be due to “potential access to care issues,” the researchers wrote. No such association was found regarding death.
Having greater disadvantage was not associated with worse survival in U.S patients. This wasn’t evaluated in Canadian patients due to the low number of deaths.
These results “demonstrated that patients who live in neighborhoods with greater disadvantage experience more severe pulmonary disease at presentation … and more rapid lung function decline,” the researchers said, adding these differences in lung function decline “may also reflect clinically meaningful differences.”
“It remains unclear whether this accelerated pulmonary progression translates to increased healthcare utilization or pulmonary-specific mortality, but established associations of progressive pulmonary sarcoidosis with high morbidity and increased mortality support that this may be the case,” they said, noting that socioeconomic status and neighborhood-level resources should be carefully assessed in order to help clinicians identify patients at higher risk of progressive pulmonary sarcoidosis.
“This work highlights the need for further studies to investigate the interactions between neighborhood-level factors and individual barriers to care, delayed specialist referral, and accelerated disease progression in patients with sarcoidosis and other chronic diseases,” the researchers wrote.
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