Assessment of the psychometric properties of an English version of the cancer dyspnea scale in people with advanced lung cancer.
CONTEXT
Dyspnea is a poorly understood subjective sensation. Existing dyspnea measures fail to adequately address its multidimensionality. A Japanese group developed and validated the Cancer Dyspnea Scale (CDS) for assessing dyspnea in patients with advanced lung cancer.


OBJECTIVES
We evaluated the validity and reliability of the English version of the CDS (CDS-E) that has 12 items and takes, on average, 140 seconds for individuals to complete.


METHODS
Eligible patients had advanced lung cancer, consented, and were fluent in English. Participants completed a 100 mm visual analogue scale (VAS), the modified Borg scale, the CDS-E, the Hospital Anxiety and Depression Scale, and the Functional Assessment of Cancer Therapy--Lung quality-of-life scale. Demographic, radiographic, and treatment information were obtained from patients' medical records.


RESULTS
One hundred twelve participants were enrolled at three sites in the U.S., Australia, and the U.K. Mean age was 64.5 years (SD 11.5); 90% were Caucasian, 68% had Eastern Cooperative Oncology Group performance status 0-1, and 50% had non-small cell carcinoma. All completed the CDS-E independently, without difficulty. The CDS-E had reasonable internal consistency overall (Cronbach's α = 0.71) and for each of the three factors (effort, anxiety, discomfort Cronbach's α = 0.80-0.84). CDS-E scores were significantly correlated with the 100mm VAS (r = 0.82; P < 0.001) and the modified Borg (r = 0.87; P < 0.001). After factor analysis, the CDS-E was revised by removing three items (r-CDS-E).


CONCLUSION
The CDS-E and r-CDS-E are reliable and valid measures of the sensation and the psychological components of dyspnea, with the shorter version having similar psychometric properties.