Does quality of life of COPD patients as measured by the generic EuroQol five-dimension questionnaire differentiate between COPD severity stages?
OBJECTIVE
To assess the discriminative properties of the EuroQol five-dimension questionnaire (EQ-5D) with respect to COPD severity according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria in a large multinational study.


METHODS
Baseline EQ-5D visual analog scale (VAS) scores, EQ-5D utility scores, and St. George Respiratory Questionnaire scores were obtained from a subset of patients in the Understanding the Potential Long-term Impact on Function with Tiotropium trial, which was a 4-year placebo-controlled trial designed to assess the effect of tiotropium on the rate of decline in FEV(1) in COPD patients aged > or = 40 years, an FEV(1) of < 70% predicted, an FEV(1)/FVC ratio of < or = 70%, and a smoking history of >/= 10 pack-years.


RESULTS
A total of 1,235 patients (mean post bronchodilator FEV(1), 48.8% predicted) from 13 countries completed the EQ-5D. The EQ-5D VAS and utility scores differed significantly among patients in GOLD stages 2, 3, and 4, also after correction for age, sex, smoking, body mass index (BMI), and comorbidity (p < 0.001). The mean EQ-5D VAS scores for patients in GOLD stages 2, 3, and 4 were 68 (SD, 16), 62 (SD, 17), and 58 (SD, 16), respectively. The mean utility scores were 0.79 (SD, 0.20) for patients in GOLD stage 2, 0.75 (SD, 0.21) for patients in GOLD stage 3, and 0.65 (SD, 0.23) for patients in GOLD stage 4. Effect sizes for the difference in utility scores between patients in GOLD stages 3 and 4 were more than twice as high as those for the difference between patients in GOLD stages 2 and 3. Gender, postbronchodilator FEV(1) percent predicted, the number of hospital admissions and emergency department visits in the year prior to baseline measurements, measures of comorbidity, and BMI were independently associated with EQ-5D utility. EQ-5D utility scores also differed between patients from different countries. French patients especially had lower utility scores than US patients. Utility scores calculated with the US value set were on average 5% higher than those calculated with the UK value set.


CONCLUSIONS
Increasing severity of COPD was associated with a significant decline in EQ-5D VAS scores and utility scores. These results demonstrate that a generic instrument can assess COPD impact on quality of life and that the scores discriminate between patient groups of known severity. These utility scores will be useful in cost-effectiveness assessments.
Rutten-van Mölken
Maureen P M H
MP
Erasmus MC, Institute for Medical Technology Assessment (IMTA), PO Box 1738, 3000 DR Rotterdam, the Netherlands. m.rutten@bmg.eur.nl
Oostenbrink
Jan B
JB
Tashkin
Donald P
DP
Burkhart
Deborah
D
Monz
Brigitta U
BU
D000203:Activities of Daily Living / Q000523:psychology; D000368:Aged; D015992:Body Mass Index; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D015897:Comorbidity; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification / Q000175:diagnosis / Q000188:drug therapy / Q000523:psychology*; D011788:Quality of Life / Q000523:psychology*; D012602:Scopolamine Derivatives / Q000627:therapeutic use*; D012648:Self Care / Q000523:psychology; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires; D000069447:Tiotropium Bromide; D014797:Vital Capacity / Q000187:drug effects
D001993:Bronchodilator Agents; D012602:Scopolamine Derivatives; D000069447:Tiotropium Bromide