Defining and grading an obstructive ventilatory defect (OVD): ‘FEV₁/FVC lower limit of normal (LLN) vs. Z-score’ and ‘FEV₁ percentage predicted (%pred) vs. Z-score’

Abstract

An obstructive ventilatory defect (OVD) is defined by a low forced expiratory volume/‘forced/slow’ vital capacity (FEV1/FVC) (e.g. <lower limit of normal (LLN)). However, the LLN can be estimated either by the 90% confidence interval (or the 90th percentile) (American Thoracic and the European Respiratory Societies (ATS/ERS) method) or by the Z-score (global lung initiative (GLI) method). In 2014, a new alternative classification (GLI classification) for grading the OVD severity was proposed to replace the 2005-ATS/ERS one. The aims of the present study were to determine, according to the two methods (GLI vs. ATS/ERS), the frequency of participants having an OVD; and to compare the two classifications (GLI vs. ATS/ERS) of OVD severity. This was a prospective study including 1000 participants (mean age = 41 ± 10 years). The OVD was defined according to the ATS/ERS [FEV1/FVC < LLN (=local norms value − 1.64 × residual standard deviation)] and GLI (FEV1/FVC Z-score < −1.64) criteria. The following OVD classifications severity were applied: ATS/ERS (FEV1%pred): mild (>70%), moderate (60–69%), moderately severe (50–59%), severe (35–49%), and very severe (<35%) and GLI (FEV1Z-score): mild (≥ −2.0), moderate (−2.0 to −2.5), moderately severe (−2.5 to −3.0), severe (−3.0 to −4.0), and very severe (<−4.0). The frequencies of OVD were 14.4% (ATS/ERS method) and 10.5% (GLI method) (p < 0.05). Among the 103 participants having an OVD according to the two methods, the severity classification was mild (34.95% vs. 37.86%, p < 0.05), moderate (25.24% vs. 18.45%, p < 0.05), moderately severe (23.30% vs. 15.53%, p = 0.144), severe (9.71% vs. 20.39%, p < 0.05), and very severe (6.80% vs. 7.77%, p = 0.785), respectively for the ATS/ERS and GLI classifications. The two OVD definitions were not exchangeable. Moreover, the two grading severity systems misclassified the OVD grades.

Deviations of body functions and structure, activity limitations, and participation restrictions of the International Classification of Functioning, Disability, and Health model in children with cystic fibrosis and non–cystic fibrosis bronchiectasis

“…Spirometry data could not reflect the severity of lung disease determined by HRCT scans in non‐CF bronchiectasis 25 . In this study, although children and adolescents with pediatric respiratory disorders had mild obstruction level according to FEV 1 %pred (>%70) and FEV 1 z score (≥−2), 16 the cause of lower FEV 1 %pred and FEV 1 z score values in non‐CF bronchiectasis children than the those of children with CF may be related with the size of the affected area in the lungs and motivation or cooperation level of children or adolescents in these group with test.…”

“…The best maneuver of technically acceptable and complying with one another by 95% from three maneuvers was selected for analysis 15 . Obstructive ventilator defect was determined according to the percentage of forced expiratory volume in 1 second (FEV 1 percentage predicted [%pred]) and calculated FEV 1 z score according to the global lung initiative reference values and used for analysis 16 …”

The multi‐ethnic global lung initiative 2012 (GLI-2012) norms reflect contemporary adult's Algerian spirometry

“…In order to simplify comparative studies between countries, to avoid mistakes due to age-related gaps in norms [ 48 ] and to simplify the conversion to norms for diverse ethnic groups, the authors acclaim implementation of the GLI-2012 spirometric norms in healthcare in Algeria. While, local spirometric data are available for children aged 6 to 16 years [ 49 ] , there is a need to evaluate the applicability of the GLI-2012 in that age range.…”

The global lung function initiative 2021 (GLI-2021) norms provide mixed results for static lung volumes (SLVs) in Algerian adults

“…First, since the GLI data repository accepts additional datasets from individuals of ‘non-European’ ancestry, Algerian SLVs data will be submitted to that repository. Second, in order to simplify comparative studies between countries, and to avoid mistakes due to age-related gaps in norms [ 45 ], the authors acclaim the implementation of the GLI-2021 norms [ 7 ] in healthcare in Algeria. However, as recommended by the GLI Task Force, if GLI-2021 norms [ 7 ] are applied to Algerians, this should be clearly stated to ensure that results are not misinterpreted.…”