Introduction:

The ATS/ERS interpretative standardization of pulmonary function tests is in constant update.

Objective:

To compare ATS/ERS recommendations for 2005 (R1) and 2021 (R2) in defining Obstructive ventilatory disease (OVD) and in classifying its severity.

Patients and methods:

It was a retrospective study (2019-2022) that included 500 patients. All patients underwent spirometry with measurement of FEV1 and FVC. An OVD was considered according to R1 when FEV1/FVC ratio is under the LLN and when the z-score of FEV1/FVC ratio is under -1.645 according to R2. For the severity levels of airflow obstruction: ATS/ERS previously recommended the use of percent predicted FEV1 with 5 levels using cut values of 70%, 60%, 50% and 35%. It is now updated for z-scores with cut values of -2, -2.5 and -4.

Results:

Mean age was 51.03±22.16 years. For making the diagnosis, both definitions were similar except one patient. OVD was diagnosed in 198 patients. For the classification of OVD severity, the following proportions were assessed: 72 mild, 29 moderate,32 moderately severe, 43 severe and 21 very severe vs 59 mild, 84 moderate, 19 severe and 35 unclassified (z-score of FEV1 above -1.645). Unclassified OVD (R2) was considered according to R1 as mild. Mild OVD (R2) was distributed according to R1 into 31 mild, 17 moderate, 7 moderately severe and 4 severe OVD. Moderate OVD (R2) was dispatched using R1 to 6 mild, 12 moderate, 25 moderately severe, 31 severe and 10 very severe. Severe OVD (R2) was classified as 8 severe and 11 very severe.

Conclusion:

ATS/ERS new and previous recommendations seem to be similar in defining OVD. However, discrepancies were assessed in classifying its severity.