The recent multi‐ethnic global lung initiative 2012 (GLI 2012 ) reference values
The recent multi‐ethnic global lung initiative 2012 (GLI2012) reference values
don’t reflect contemporary Mediterranean spirometryBen Saad H1,2, Elattar Mn1, Hadj Mabrouk K1, Maatoug C1, Rouatbi S21Functional Exploration Laboratory. Occupational Medicine Group. 2Department of Physiology and Functional Explorations.
Farhat HACHED Hospital. Sousse. Tunisia
Chi-2 test: compare percentages..
Student t-test: compare anthropometric and spirometric data.
Wilcoxon matched pairs test: compare %Ref.
Construction of contingency tables: comparison of spirometry profiles (normal, LAOVD, SAOVD, TRVD, MVD).
Z-score (ERS/GLI2012): >0.5 is considered to be clinically significant and equated to a change in %Ref of approximately 6%.
The applicability of the recent multi-ethnic reference equations derived by the ERS Global Lung Initiative (ERS/GLI) in interpreting spirometry data in Mediterranean population (eg.Tunisian subjects) has not been studied
To ascertain how well the recent ERS/GLI reference equations(1) ﬁt contemporary Tunisian spirometric data.
Design: cross-sectional study.
Total sample: local workers aged 18-60 Yrs and having a complete record with technically acceptable and reproducible spirometry maneuvers.
Healthy non-smokers group free from large airways obstructive ventilatory defect (LAOVD) or mixed ventilatory defect. (MVD) according local reference equations(2) .
Medical questionnaire and smoking habits.
Anthropometric data: age (Yr), height (m), weight, (kg), body mass index.
Spirometry measurements according ATS/ERS-2005 guidelines.
Spirometric data:FVC (L), FEV1(L), FEV1/FVC, PEF (L/s), forced expiratory flow rate at the x% point of total volume to be exhaled (FEFx, L/s), maximal mid-expiratory flow (MMEF, L/s) and Z-score.
Applied reference equations: ERS/GLI2012 and Tunisia1995
Data expression: absolute values and percent of reference values (%Ref Tunisian1995 and %Ref ERS/GLI2012).
LAOVD: FEV1/FC < lower limit of normal (LLN).
SAOVD (small airway obstructive ventilatory defect): FEV1/FVC ≥LLN and FVC ≥LLN and MMEF <LLN.
TRVD (tendency through a restrictive ventilatory defect): FEV1 <LLN and FVC < LLN and FEV1/FVC ≥ LLN.
MVD: FEV1/FVC <LLN and FVC <LLN and FEV1<LLN.
How well did the recent ERS/GLI2012 reference equations ﬁt contemporary Tunisian spirometric data?
Mean±SD Z-scores for the contemporary healthy group data (n=489) are
-0.55±0.87 (FEV1), -0.62±0.86 (FVC), 0.10±0.73 (FEV1/FVC), 4.43±0.69 (FEF75) and 0.07±0.93 (MMEF).
Mean Z-score differences equate to percent predicted differences of 6.95% (FEV1), 7.73% (FVC), 400% (FEF75), 4.37% (MMEF) and 0.59%.(FEV1/FVC).
The use of the ERS/GLI2012 reference equations leads to misinterpretation of spirometry data in a significant proportion of subjects.
Our results don’t support the use of the ERS/GLI2012 reference equations to interpret spirometry in Tunisian population and probably in Mediterranean population.
Comparison of measured spirometric data expressed as a reference percent from the 2 reference equations
All measured spirometric data (except for FVC) expressed as %Ref ERS/GLI2012 are significantly higher than those expressed as a %Ref Tunisia1995: mean±SD of FEV1, FEV1/FVC, MMEF and FEF75 are, respectively, 90±12 vs. 85±12%, 99±8 vs. 98±8%, 99±31 vs. 70±20% and 511±153 vs. 92±21%.
Quanjer PH et al. (2012) Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations. Eur Respir J 40: 1324-1343.
Tabka Z et al. Spirometric reference values in a Tunisian population. Tunis Med. 1995;73:125-31.