Characteristics and Outcomes of HEDIS-Defined Asthma Patients with COPD Diagnostic Coding

Abstract

Background: Little is known of the disease burden of patients with persistent asthma (PA) who also have a chronic obstructive pulmonary disease (COPD) diagnosis code (AS-COPD).

Objective: The objective of this study was to characterize and compare patients with AS-COPD with those with PA without COPD diagnosis, and determine in AS-COPD the relationship between blood eosinophil count and future asthma exacerbations.

Methods: This retrospective cohort study used administrative pharmacy and health care utilization data to identify, characterize, and compare the burden and asthma exacerbations in adults with AS-COPD (N = 901) with those with PA (N = 2392). Negative binomial regression and Poisson regression models were used to evaluate the relationships between baseline blood eosinophil counts (high vs low) based on various cutoff points and asthma exacerbations in the follow-up year, adjusting for demographics, comorbidities, and asthma burden.

Results: Compared with patients with PA, those with AS-COPD were significantly (all P < .001) older, more frequently female, less well educated, more likely to be or have been a smoker, had more comorbidities, received more asthma controller medications, and had greater rates and frequencies of asthma exacerbations, but had similar blood eosinophil counts. The rate of asthma exacerbations/person-year in AS-COPD during follow-up was 1.61 (95% CI, 1.18-2.20). Patients with AS-COPD with a blood eosinophil count ≥400 cells/mm(3) had an increased rate of future asthma exacerbations compared with those whose blood eosinophil count was <400 cells/mm(3) (adjusted rate ratio, 1.44, 95% CI, 1.09-1.90).

Conclusions: Compared with patients with PA, those with AS-COPD had more disease burden, but a similar relationship of high blood eosinophil count to more future asthma exacerbations. These findings suggest a common inflammatory component between AS-COPD and PA.

Keywords: Asthma; Asthma control; Asthma guidelines; Asthma impairment; Asthma risk; COPD; Eosinophils; GINA step-care level; Managed care.