Clinical variables impacting on the estimation of utilities in chronic obstructive pulmonary disease

Health utilities are widely used in health economics as a measurement of an individual's preference and show the value placed on different health states over a specific period. Thus, health utilities are used as a measure of the benefits of health interventions in terms of quality-adjusted life years. This study aimed to determine the demographic and clinical variables significantly associated with health utilities for chronic obstructive pulmonary disease (COPD) patients.

This was a multicenter, observational, cross-sectional study conducted between October 2012 and April 2013. Patients were aged ≥40 years, with spirometrically confirmed COPD. Utility values were derived from the preference-based generic questionnaire EQ-5D-3L applying weighted Spanish societal preferences. Demographic and clinical variables associated with utilities were assessed by univariate and multivariate linear regression models.

Three hundred and forty-six patients were included, of whom 85.5% were male. The mean age was 67.9 (standard deviation [SD] =9.7) years and the mean forced expiratory volume in 1 second (%) was 46.2% (SD =15.5%); 80.3% were former smokers, and the mean smoking history was 54.2 (SD =33.2) pack-years. Median utilities (interquartile range) were 0.81 (0.26) with a mean value of 0.73 (SD =0.29); 22% of patients had a utility value of 1 (ceiling effect) and 3.2% had a utility value lower than 0. The factors associated with utilities in the multivariate analysis were sex (beta =-0.084, 95% confidence interval [CI]: -0.154; -0.013 for females), number of exacerbations the previous year (-0.027, 95% CI: -0.044; -0.010), and modified Medical Research Council Dyspnea Scale (mMRC) score (-0.123 [95% CI: -0.185; -0.061], -0.231 [95% CI: -0.301; -0.161], and -0.559 [95% CI: -0.660; -0.458] for mMRC scores 2, 3, and 4 versus 1), all P<0.05.

Multivariate analysis showed that female sex, frequent exacerbations, and an increased level of dyspnea were the main factors associated with reduced utility values in patients with COPD.