Reference values of impulse oscillometric lung function indices in adults of advanced age.

Impulse oscillometry (IOS) is a non-demanding lung function test.
Its diagnostic use may be particularly useful in patients of
advanced age with physical or mental limitations unable to perform
spirometry. Only few reference equations are available for
Caucasians, none of them covering the old age. Here, we provide
reference equations up to advanced age and compare them with
currently available equations. IOS was performed in a
population-based sample of 1990 subjects, aged 45-91 years, from
KORA cohorts (Augsburg, Germany). From those, 397 never-smoking,
lung healthy subjects with normal spirometry were identified and
sex-specific quantile regression models with age, height and body
weight as predictors for respiratory system impedance, resistance,
reactance, and other parameters of IOS applied. Women (n = 243)
showed higher resistance values than men (n = 154), while reactance
at low frequencies (up to 20 Hz) was lower (p