Reconsidering the arm span-height relationship in patients referred for spirometry

The interpretation of pulmonary function tests relies on reference values corrected for age, sex and height. Height may be difficult to measure in patients with deformities of the thoracic cage or those unable to stand up properly. Current practice is to substitute arm span to height, once corrected either by a fixed factor or by an age- and sex-dependent regression equation. However arm span may be difficult to measure in some patients. This study evaluated the relationship between arm span, measured height, height as mentioned on an identity document (ID), sex and age in a population of 2,452 Caucasian subjects with no chest or spine deformities. The present study demonstrates that age and sex have to be taken into account to best predict height from arm span or ID height values. The equations predicting height from ID height give the best diagnosis concordance compared to reference in males and females. Age correction does not improve concordance below 70 yrs. The estimation of height from ID height can be substituted to that from arm span when clinically relevant, providing ID height has been measured before the occurrence of stature problems.