FEV1:FVC Threshold Identifies Individuals at Risk for Clinically Significant COPD

The use of airflow obstruction that is defined as a ratio of forced expiratory volume in 1 second to forced vital capacity (FEV₁:FVC) of <0.70 can help identify individuals at risk for clinically significant chronic obstructive pulmonary disease (COPD), including COPD-related hospitalizations and death.

The current National Heart, Lung, and Blood Institute (NHLBI) Pooled Cohorts Study harmonized and pooled data from 4 US general population-based cohorts: Atherosclerosis Risk in Communities Study, Cardiovascular Health Study, Health, Aging, and Body Composition Study; and Multi-Ethnic Study of Atherosclerosis. Results of the analysis were published in the Journal of the American Medical Association.

Investigators sought to establish the discriminative accuracy of various FEV₁:FVC thresholds for the prediction of COPD-related mortality and hospitalization. Participants between the ages of 45 and 102 years were enrolled in the NHLBI Pooled Cohorts Study from 1987 to 2000 and were followed longitudinally through 2016. The primary study outcome was a composite of COPD hospitalization and COPD-related mortality.

A total of 24,207 adult patients were included in the pooled cohort. The mean participant age at enrollment was 63±10.5 years. Overall, 54% of the patients were women, 69% were non-Hispanic whites, and 63% were ever-smokers. Complete data were available for 77% of the participants.

At a median follow-up of 15 years, 3925 of the participants experienced COPD-related events during 340,757 person-years of follow-up (incidence density rate of 11.5 per 1000 person-years), which included 3563 COPD-related hospitalizations and 447 COPD-related deaths. Regarding the discrimination of COPD-related events, the optimal fixed threshold of 0.71 for discriminating COPD-related events did not differ significantly from the 0.70 threshold (difference, 0.0001; 95% CI, -0.002 to 0.004) but was more accurate than the lower limit of normal threshold (difference, 0.034; 95% CI, 0.028-0.041). In addition, the 0.70 threshold provided optimal discrimination in the subgroup analysis that included ever-smokers, as well as in adjusted models.

A major limitation of the study was the use of prebronchodilator spirometry values to confirm airflow obstruction. Further, no adjustments were made for medication use. Moreover, because participants were selected across the 4 cohorts, baseline differences in demographics and differences in disease management over time were involved.

The investigators concluded that the results of this study support the use of FEV₁:FVC <0.70 for the identification of those individuals at risk for clinically significant COPD.

Reference

Bhatt SP, Balte PP, Schwartz JE, et al. Discriminative accuracy of FEV₁:FVC thresholds for COPD-related hospitalization and mortality. JAMA. 2019;321(24):2438-2447.