Race-specific spirometry may miss emphysema diagnoses

Spirometry alone misses cases

“We were surprised by the substantial rates of emphysema we saw among Black men in our cohort with normal spirometry,” Dr. Liu said in an interview. “We did not expect to find than more than one in eight Black men with an FEV₁ between 100% and 120% predicted would have emphysema – a rate more than six times higher than White men with the same range of FEV₁.”

“One takeaway is that we are likely missing a lot of people with impaired respiratory health or true lung disease by only using spirometry to diagnose COPD,” said Dr. Liu. In clinical practice, “physicians should consider ordering CT scans on patients with normal spirometry who have respiratory symptoms such as cough or shortness of breath. If emphysema is found, physicians should discuss mitigating any potential risk factors and consider the use of COPD medications such as inhalers.

“Our findings also support using race-neutral reference equations to interpret spirometry instead of race-specific equations. Racial disparities in rates of emphysema among those with ‘normal’ FEV₁ [between 80% and 120% predicted], were attenuated or eliminated when race-neutral equations were used to calculate FEV₁. This suggests that race-specific equations are normalizing worse lung health in Black adults,” Dr. Liu explained.

“We need to continue research into additional tools that can be used to assess respiratory health and diagnose COPD, while keeping in mind how these tools may affect racial disparities,” said Dr. Liu. “Our study suggests that our reliance on spirometry measures such as FEV₁/FVC ratio and FEV₁ is missing a number of people with respiratory symptoms and CT evidence of lung disease, and that this is disproportionately affecting Black adults in the United States.” Looking ahead, “it is important to find better tools to identify people with impaired respiratory health or early manifestations of disease so we can intercept chronic lung disease before it becomes clinically apparent and patients have sustained significant lung damage.”

The CARDIA study was supported by the National Heart, Lung, and Blood Institute in collaboration with the University of Alabama at Birmingham, Northwestern University, the University of Minnesota, and the Kaiser Foundation Research Institute. Dr. Liu was supported by a grant from the National Institutes of Health. The researchers had no financial conflicts to disclose. Dr. Pal had no financial conflicts to disclose.

*This article was updated 7/22/2022.