NEJM Journal Watch
David J. Amrol, MD, reviewing
This practice doesn’t help predict adverse respiratory events.
When interpreting spirometry, published normative values differ among various ethnic groups. In the U.S., spirometers use either race-specific reference values based on the National Health and Nutrition Examination Survey III (conducted from 1988–1994), or a “correction factor” which assumes forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) values for Black patients are roughly 15% lower than for white patients of the same sex, height, and age.
Researchers examined data from the MESA Lung Study, in which 3344 middle-aged and older U.S. adults (mean age, 65) without known chronic lower respiratory disease underwent spirometry between 2004 and 2006. Participants who self-identified as Black, white, Asian, or Hispanic were followed until 2016 to identify the incidence of chronic lower respiratory events. Mean FVC was 600 cc lower in Blacks, 200 cc lower in Hispanics, and 700 cc lower in Asians than in whites. Using race-based correction factors did not help predict chronic lower respiratory disease events during follow-up. When a correction factor was used, FVC had to be 17% lower in a Black participant than in a white participant for a restrictive pattern (FVC <70% predicted) to be diagnosed.
When I was a resident, I was taught that Black patients have lower lung volumes than do white patients and that the reason was smaller torso-to-leg ratio. Causes such as higher prematurity rates, malnutrition, more indoor and outdoor air pollution, and less access to medical care were not considered. I did not appreciate that these correction factors might require a Black man to work longer in a dangerous setting before being deemed at risk, or that his decline in lung function would have to be 17% greater to get disability resources, or that he might have a delay in treatment for respiratory disease because his lung function was “normal” after correction factors were applied. The authors and an editorialist recommend that we stop using race adjustment for interpretation of spirometry. This interesting article (Can J Respir Ther 2015; 51:99) gives historical context on the racist undertones of spirometry correction factors.
Elmaleh-Sachs A et al. Race/ethnicity, spirometry reference equations, and prediction of incident clinical events: The Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study. Am J Respir Crit Care Med 2022 Mar 15; 205:700. (https://doi.org/10.1164/rccm.202107-1612OC)
Schluger NW. The vanishing rationale for the race adjustment in pulmonary function test interpretation. Am J Respir Crit Care Med 2022 Mar 15; 205:612. (https://doi.org/10.1164/rccm.202112-2772ED)