Repeated Measures of FEV1 Over Six to Twelve Months: What Change is Abnormal?

Monitoring change in FEV1 (deltaFEV1) is useful for assessing adverse respiratory effects in an individual, but high variability impedes reliable recognition of accelerated decline. The American Thoracic Society (ATS) recommends a > or =15% year-to-year FEV1 decline for clinical significance. To evaluate the applicability of this criterion in health monitoring programs, we examined the mean, lower 5th percentile, and lower 5% cutoff value of...