Pulmonary function in a cohort of heart-healthy individuals from Northern Sweden - A comparison of reference values
Background Dynamic spirometry is an important investigation to differentiate between impaired and normal lung function, stressing the importance of selecting consistant and reliable clinical reference data. This study aims to evaluate the results of lung function testing in subjects without known heart or pulmonary disease living in Northern Sweden, with a focus on a comparison with previously published reference materials. Methods The study is based on 285 (148 males) healthy adults, 20-90
... s of age. The subjects had been randomly selected and included in a study of cardiac function in heart-healthy subjects and were also assessed with dynamic spirometry, where 16 subjects presented with pulmonary functional impairments and were excluded. The sex-specific age-dependency in lung volumes was estimated using the LMS model, where non-linear equations are derived for the mean value (M), the location (L) or skewness, and the scatter (S) or coefficient of variation. A comparison was made with the reference values given by the original LMS model that is suggested by the Global Lung Initiative (GLI), and with the reference values from the recent Obstructive Lung Disease In Norrbotten (OLIN) study, which is also based on subjects from Northern Sweden. Results No differences were found in the age-dependency of pulmonary function between the new LMS model and the OLIN model. The original GLI reference values suggested significantly lower normal values, and consequently resulted in fewer subjects with both FEV1 and FVC values below the lower limit of normality, than both the new model and the OLIN model. Conclusions Our results are in line with previous reports and support that the original GLI reference values underestimate pulmonary function in the adult Swedish population. This underestimation could be reduced by updating the coefficients in the underlying LMS model with values that are specific for Swedish citizens. For optimal accuracy the final coefficients should be verified in a larger cohort.