Confirmed: FEV1:FVC <0.70 proves to be the optimal threshold to identify risk of COPD vs less than LLN and other fixed values.
The value is based primarily on expert opinion, however, with no population-based research to support it. A study published in JAMA in June supports continued use of the FEV1/FVC ratio of <.70 in the diagnosis of COPD.1 While study authors note there is more work to be done to refine COPD diagnostics further, clinicians can feel comfortable using spirometry for now. Click through the slideshow above to get the study results and implications for clinical practice.
FEV1/FVC Cutoff for COPD? It’s Controversial. Many guidelines recommend FEV1/FVC <.70 as the cutoff, but they are based mainly on expert opinion instead of population-based evidence and they do not account for normal variation in lung function. Another approach uses FEV1/FVC <LLN which is determined from population data. Which is the most accurate approach?
NHLBI Pooled Cohort Study. The NHLBI study pooled data from 4 large, multi-ethnic studies in the US and had a total of 24 207 participants with a mean age of 63 years. The primary outcome was the composite of COPD hospitalization and death, which was determined using the Harrell C statistic (C statistic). The C statistic evaluates accuracy for a range of FEV1/FVC cutoffs in predicting primary outcome.
Results Support Accuracy of FEV1/FVC <.70. During a median follow-up of 15 years, 3925 participants experienced COPD-related events over 340â¯757 person-years of follow-up, including 3563 COPD-related hospitalizations and 447 COPD-related deaths. Further results showed no significant difference between FEV1/FVC 0.70 and the optimal cutoff of 0.71; LLN cutoff was significantly less accurate vs optimal cutoff of 0.71; and the optimal FEV1/FVC cutoff for ever-smokers was 0.70.
1. Bhatt SP, Balte PP, Schwartz JE, et al. Discriminative accuracy of FEV1:FVC thresholds for COPD-related hospitalization and mortality. JAMA. 2019;321:2438-2447.
2. Vestbo J, Lange P. Accuracy of airflow obstruction thresholds for predicting COPD-related hospitalization and mortality: Can simple diagnostic thresholds be used for a complex disease? 2019;321:2412-2413.
The ratio of the forced expiratory volume in the first second to the forced vital capacity (FEV1/FVC) is measured relatively easily in the clinic using spirometry. Many professional organizations (eg, American College of Physicians, American College of Chest Physicians, European Respiratory Society) have long recommended the ratio of FEV1/FVC