Increased BMI not linked to greater risk for sarcoidosis
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A higher BMI did not appear to increase risk for sarcoidosis, according to study results published in CHEST.
Additionally, patients with obstructive sleep apnea had lower odds for being diagnosed with sarcoidosis than patients without OSA, according to researchers.
“This study has prompted clinicians to reevaluate the association of obesity with sarcoidosis,” Marc A. Judson, MD, professor of medicine and chief of the division of pulmonary and critical care medicine at Albany Medical College, told Healio. “To our great surprise, our analysis found that not only was obesity not associated with sarcoidosis, it was less likely that obese patients would develop sarcoidosis. Since we analyzed more than 10,000 sarcoidosis patients and over 2,000,000 control patients, the odds of our findings being from a sampling error are essentially zero. There was also no association of sarcoidosis with obstructive sleep apnea.”
In a retrospective case-controlled study, Judson and colleagues assessed 10,512 patients with sarcoidosis (mean age, 55.5 ± 12.1 years; 85.1% men; 52% white) and 2,709,884 patients without sarcoidosis (mean age, 59.2 ± 15.6 years; 92.6% men; 78.9% white) from a U.S. Veterans Health Administration database to determine if BMI or OSA was related to the development of the disease.
For patients with sarcoidosis, researchers obtained at least one BMI value taken 1 year prior to their diagnosis. Patients without sarcoidosis had their BMIs recorded over intervals at 3, 6 and 12 months before a random date.
Mean BMI appeared comparable between those with sarcoidosis (30.9 kg/m2) and those without sarcoidosis (31 kg/m2). Significantly fewer patients with vs. without sarcoidosis had OSA (10% vs. 16.8%; P < .0001).
According to logistic regression models adjusted for age, sex, race and OSA diagnosis, BMI recorded at 12 months prior to diagnosis was not linked to sarcoidosis development (OR = 1.002; 95% CI, 0.999-1.005).
“These results did surprise us and the entire sarcoidosis community,” Judson said. “Three previous studies had shown that obesity was a risk factor for sarcoidosis.”
Despite significant ORs for BMI 3 and 6 months prior to a sarcoidosis diagnosis and results of previous studies, post hoc statistical power calculations confirmed the observed outcome.
“Given the humongous size of our database, it is problematic to refute the results,” Judson said. “However, this has led to questions about several previous studies performed concerning this issue where there was an association seen between obesity and sarcoidosis. One difference between our study and previous work is that we examined each individual’s weight and BMI at 3, 6 and 12 months prior to their diagnosis of sarcoidosis. Previous studies examined weight earlier in life, such as at early adulthood. Perhaps lifestyle events and weight gain earlier in life increase the odds of developing sarcoidosis, but recent weight gain/obesity does not.”
For patients with vs. without OSA, researchers observed lower odds (OR = 0.525; 95% CI, 0.492-0.56) for sarcoidosis at 12 months in a logistic regression model stratified by age, sex, race and BMI. A conditional logistic regression model yielded similar results in this cohort, as well as data from 3 and 6 months.
Additionally, researchers found that the odds for a sarcoidosis diagnosis increased among patients who were women (12 months, OR = 1.576; 95% CI, 1.489-1.667), Black (12 months, OR = 3.639; 95% CI, 3.497-3.785) and older (12 months, OR = 0.992; 95% CI, 0.991-0.994).
This study by Judson and colleagues adds to the literature indicating that BMI can sometimes be a complex and limiting measurement in studies, according to an accompanying editorial by Yvette C. Cozier, DSc, MPH, of the Slone Epidemiology Center at Boston University, and colleagues. According to the authors, an example of BMI’s limitations include the proportions of lean mass vs. body fat and unmeasured central adiposity.
“Future research must be clear about what is being measured when BMI is used as a primary exposure variable,” Cozier and colleagues wrote. “Researchers must distinguish between hypothesizing that ‘mass’ vs. adiposity, more specifically the inflammatory and metabolic properties of adipose tissue, contributes to the risk of sarcoidosis. Given this framework, all future studies in this space should use as many anthropometric and inflammatory measures as are available. Until then, the BMI remains an index under suspicion.”
For more information:
Marc A. Judson, MD, can be reached at judsonm@amc.edu.