Abstract
Vertebral deformities are prevalent in chronic obstructive pulmonary disease (COPD) patients and may cause excessive loss of height. As height is used for calculating reference values for pulmonary function tests, larger than normal height reduction could cause overestimation of lung function.
In this cross-sectional study of 465 COPD patients and 462 controls, we explored how often lung function is misinterpreted due to height reduction in COPD patients, and whether the number or severity of vertebral deformities correlate with height reduction.
Measured height was compared to recalled tallest height (RTH) and height calculated from arm span (ASH) to assess height reduction. Vertebral deformities were assessed from radiographs and pulmonary function was assessed using standard formulae.
Height reduction was frequent in both the study and control groups, and increased with the number and severity of vertebral deformities. When using current measured height, lung function was overestimated in a significant proportion of COPD patients at relatively modest height reductions. The effects were smallest for forced expiratory volume in 1 s and forced vital capacity, and most pronounced for total lung capacity and residual volume. Therefore, we propose that in COPD patients with excessive height reduction, one might use RTH or ASH in calculating predicted values. Furthermore, such patients should be evaluated for co-existing vertebral deformities and osteoporosis.
- Chronic obstructive pulmonary disease
- height reduction
- lung function
- pulmonary function test
- spinal deformity index
- vertebral deformities
Footnotes
Support Statement
This project has been financed with the aid of funds from the Norwegian Foundation for Health and Rehabilitation, The Norwegian Heart and Lung Patient Organization (LHL), and GlaxoSmithKline via The Norwegian Thoracic Society.
Statement of Interest
Statements of interest for all authors can be found at www.erj.ersjournals.com/misc/statements.dtl
- Received September 21, 2009.
- Accepted January 8, 2010.
- ©2010 ERS