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Spirometric reference equations for Swedish adults
Author(s) -
Brisman Jonas,
Kim JeongLim,
Olin AnnaCarin,
Torén Kjell,
Bake Björn
Publication year - 2017
Publication title -
clinical physiology and functional imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.608
H-Index - 67
eISSN - 1475-097X
pISSN - 1475-0961
DOI - 10.1111/cpf.12349
Subject(s) - piecewise linear function , medicine , linear equation , population , reference values , statistics , piecewise , mathematics , estimating equations , limit (mathematics) , lung function , normal distribution , mathematical analysis , lung , maximum likelihood , environmental health
Summary New spirometric reference equations for Swedish adults are required. Three different older sets of reference equations clinically used in Sweden have various drawbacks and the recently published ‘The Global Lung Function 2012 ( GLI ) equations’ have been shown not to be adequate for Swedish normal, healthy non‐smokers. We have recently concluded that a piecewise linear model presented by Lubinski and Gólczewski accurately describes the distribution of spirometric variables in a large Swedish random population sample. This piecewise linear model also offers the important advantage of implementing easily physiologically interpretable coefficients. The present study aimed at presenting piecewise linear reference equations for Swedish adults based on a random population sample of 6685 individuals aged 25–75 years. Predicted normal values by the piecewise linear reference equations and lower limit normal ( LLN ) were compared with the three reference equations frequently used clinically in Sweden and the GLI equations. We found predicted normal values according to the present piecewise linear reference equations close to 100% predicted normal as expected, whereas the other equations either overestimated or underestimated normal subjects. Concerning LLN , the present equations, i.e. 1·645 × RSD , showed the least deviation from the expected 5% and, e.g., the GLI equations systematically identified too few subjects below LLN . We conclude that the present piecewise linear reference equations, based on a relatively large general population sample, ought to be considered for clinical use in Sweden. Application of 1·645 × RSD below predicted value gave an acceptably accurate LLN .