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Respir Med. 2014 Jan;108(1):181-8. doi: 10.1016/j.rmed.2013.12.009. Epub 2013 Dec 24.

Assessing exertional dyspnea in patients with idiopathic pulmonary fibrosis.

Author information

1
Autoimmune Lung Center and Interstitial Lung Disease Program, National Jewish Health, Denver, CO, USA. Electronic address: swigrisj@njc.org.
2
Department of Psychiatry and Behavioural Neurosciences, McMaster University, Ontario, Canada.
3
Autoimmune Lung Center and Interstitial Lung Disease Program, National Jewish Health, Denver, CO, USA.
4
Morgridge College of Education, University of Denver, Denver, CO, USA.
5
Division of Pulmonary and Critical Care Medicine, Sleep and Behavioral Health Sciences Section, National Jewish Health, Denver, CO, USA.

Abstract

BACKGROUND:

Dyspnea is a hallmark symptom of idiopathic pulmonary fibrosis (IPF), and dyspnea induced physical activity limitation is a prominent driver of quality of life impairment among IPF patients.

METHODS:

We examined response data for the 21 physical activity items (the first 21 of 24) from the University of California San Diego Shortness of Breath Questionnaire (UCSD) collected at baseline in a recently conducted IPF trial. We used Rasch analysis and hypothesis testing with conventional statistical methodology to achieve three objectives: 1) to examine the items to identify the one characteristic that distinguishes one from another; 2) to asses these items for their ability to measure dyspnea severity in IPF; 3) to use the items to develop a dyspnea ruler.

RESULTS:

The sample comprised 178 subjects. The 21 items fit the Rasch model. There was very strong correlation between Rasch item severity and their metabolic equivalents (METS) values (r = -0.86, p < 0.0001). With the sample stratified on scores from the 21 items, there were significant between group differences in FVC%, DLCO% and distance walked during the six-minute walk test. The dyspnea ruler can be used to put dyspnea levels in a more easily understood clinical context.

CONCLUSIONS:

The first 21 items from the UCSD compose a unidimensional dyspnea-with-activity scale and are both sensibly ordered and distinguished from each other by their METS values. These 21 items can be used confidently to formulate clinically-relevant inferences about IPF patients and should be considered for use as a meaningful endpoint in IPF research.

KEYWORDS:

Dyspnea; Functional capacity; Idiopathic pulmonary fibrosis; Quality of life

PMID:
24388667
PMCID:
PMC3951298
DOI:
10.1016/j.rmed.2013.12.009
[Indexed for MEDLINE]
Free PMC Article

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