Global Lung Function Initiative 2012 reference equations for spirometry in the Norwegian Population

Abstract

<b>Background:</b> We studied the fit of the Global Lung Function Initiative all-age reference values to Norwegians, compared them with currently used references (European Community for Steel and Coal (ECSC) and Zapletal) and estimated the prevalence of obstructive lung disease.<br> <b>Methods:</b> Spirometry data collected in 30,239 subjects (51.7% females) aged 12-90 years in three population-based studies were converted to z-scores. Results: Healthy non-smokers comprised 2,438 adults (57.4% females) aged 20 – 90 and 8,725 (47.7% female) adolescents aged 12-19 years. The GLI-2012 prediction equations fitted the Norwegian data satisfactorily. Median (SD) z-scores were respectively 0.02 (1.03), 0.01 (1.04) and - 0.04 (0.91) for FEV1, FVC and FEV1/FVC in males, and -0.01 (1.02), 0.07 (0.97) and -0.21 (0.82) in females. The ECSC and Zapletal references significantly underestimated FEV1 and FVC. Stricter criteria of obstruction (FEV1/FVC < the GLI-2012 lower limit of normal (LLN)) carried a substantially higher risk of obstructive characteristics than FEV1/FVC < 0.7 and > GLI-2012 LLN. Corresponding comparison regarding myocardial infarction showed a fourfold higher risk for women.<br> <b>Conclusion:</b> The GLI-2012 reference values fit the Norwegian data satisfactorily and are recommended for use in Norway. Correspondingly, the FEV1/FVC GLI-2012 LLN identifies higher risk of obstructive characteristics than FEV1/FVC < 0.7.