Race-specific reference values and lung function impairment, breathlessness and prognosis: Analysis of NHANES 2007–2012

Abstract

Background Spirometry reference values differ by race/ethnicity, which is controversial. We evaluated the effect of race-specific references on prevalence of lung function impairment and its relation to breathlessness and mortality in the US population. Methods Population-based analysis of the National Health and Nutrition Examination Survey (NHANES) 2007–2012. Race/ethnicity was analyzed as black, white, or other. Reference values for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were calculated for each person using the Global Lung Initiative (GLI)-2012 equations for (1) white; (2) black; and (3) other/mixed people. Outcomes were prevalence of lung function impairment (< lower limit of normal [LLN]), moderate/severe impairment (< 50%pred); exertional breathlessness; and mortality until 31 December, 2015. Results We studied 14,123 people (50% female). Compared to those for white, black reference values identified markedly fewer cases of lung function impairment (FEV1) both in black people (9.3% vs. 36.9%) and other non-white (1.5% vs. 9.5%); and prevalence of moderate/severe impairment was approximately halved. Outcomes by impairment differed by reference used: white (best), other/mixed (intermediate), and black (worst outcomes). Black people with FEV1 ≥ LLNblack but < LLNwhite had 48% increased rate of breathlessness and almost doubled mortality, compared to blacks ≥ LLNwhite. White references identified people with good outcomes similarly in black and white people. Findings were similar for FEV1 and FVC. Conclusion Compared to using a common reference (for white) across the population, race-specific spirometry references did not improve prediction of breathlessness and prognosis, and may misclassify lung function as normal despite worse outcomes in black people.

Race-Specific Spirometry Equations Do Not Improve Models of Dyspnea and Quantitative Chest CT Phenotypes

“… 1 , 2 However, the clinical value of race adjustments has increasingly been questioned. 3 , 4 , 5 , 6 Although recent studies found no prognostic benefit of race-specific equations compared with “race-neutral” equations in mortality or respiratory events, 7 , 8 , 9 , 10 , 11 others continue to defend the use of race in prediction equations. 12 , 13 Race-specific equations are recommended by the most recent US and European guidelines 14 and are still used in clinical care and pulmonary research worldwide.…”

The prevalence and mortality risks of PRISm and COPD in the United States from NHANES 2007–2012

“…In recent years, a substantive body of research has demonstrated the bias associated with use of race-specific predictive equations [ 26 , 29 , 34 , 36 ]. As such, we avoided the use of race-specific equations in all our analyses and opted to use Hankinson’s non-Hispanic White predictive equation for all races and the GLI race-neutral predictive equation in a secondary analysis.…”

“…Given recent debates over the merits of race-specific predicative equations for spirometry, [ 28 , 29 , 34 – 36 ] in addition to Hankinson’s non-Hispanic White predictive equation of lung function, we also applied a race-neutral reference equation to explore differences in COPD prevalence and mortality. We used the Global Lung Function Initiative’s (GLI) race-neutral predictive equation for this secondary analysis [ 35 ].…”

The association of spirometric small airways obstruction with respiratory symptoms, cardiometabolic diseases, and quality of life: results from the Burden of Obstructive Lung Disease (BOLD) study

“…This restricted our ability to use multi-ethnic reference values, which could have impacted the estimation of prevalence at some sites. However, the NHANES equations have been shown to give similar prevalence estimates for airflow obstruction regardless of race-correction [ 35 ], while recent evidence suggests that race-correction may misclassify individuals with underlying disease [ 36 ].…”