The new ATS/ERS guidelines for assessing the spirometric severity of restrictive lung disease differ from previous standards

Background and Objectives: The ATS/ERS Task Force on Lung Function Testing recently proposed guidelines for the interpretation of pulmonary function tests and suggested that a reduction in FEV1 be used for categorizing both obstructive and restrictive abnormalities. This changes the severity stratification algorithm of restrictive patterns diagnosed by spirometry, that are currently categorized based on reduction in VC. This study examined the level of agreement between these two categorization schemes. Methods: Spirometry records of 2527 adult patients evaluated over 1 year were retrieved; 361 of these patients showed a restrictive pattern. Severity of airway restriction was separately assessed in these patients using the indicative schemes provided in the new ATS/ERS and the earlier ATS guidelines. Results: There were 212 (58.7%) patients with a restrictive pattern who had identical severity categorization using both guidelines. In most instances of discordance, the severity categorization differed only by a single stratum. Of 149 discordant results, 91 (60.1%) were placed in a better category, and 58 (39.9%) in a worse category, when using the new ATS/ERS recommendations. Overall weighted kappa estimate for agreement between the two schemes of categorization was 0.649. Conclusion: Based on spirometry results, the level of severity of restriction cannot be described interchangeably between the old and new guidelines for all patients. The new guidelines tend to give lower severity scores for restrictive lung diseases in up to 25% of patients.