Reference values of spirometry for Finnish adults.

Background: Diagnostic assessment of lung function necessitates up-to-date reference values. The aim of this study was to estimate reference values for spirometry for the Finnish population between 18 and 80 years and to compare them with the existing Finnish, European and the recently published global GLI2012 reference values.

Methods: Spirometry was performed for 1380 adults in the population-based FinEsS studies and for 662 healthy non-smoking volunteer adults. Detailed predefined questionnaire screening of diseases and symptoms, and quality control of spirometry yielded a sample of 1000 native Finns (387 men) healthy non-smokers aged 18-83 years. Sex-specific reference values, which are estimated using the GAMLSS method and adjusted for age and height, are provided.

Results: The predicted values for lung volumes are larger than those obtained by GLI2012 prediction for the Caucasian subgroup for forced vital capacity (FVC) by an average 6·2% and 5·1% and forced expiratory volume in 1 s (FEV1) by an average 4·2% and 3·0% in men and women, respectively. GLI2012 slightly overestimated the ratio FEV1/FVC with an age-dependent trend. Most reference equations from other European countries, with the exception of the Swiss SAPALDIA study, showed an underestimation of FVC and FEV1 to varying degrees, and a slight overestimation of FEV1/FVC.

Conclusion: This study offers up-to-date reference values of spirometry for native Finns with a wide age range. The GLI2012 predictions seem not to be suitable for clinical use for native Finns due to underestimation of lung volumes.