Cost and utilization of COPD and asthma among insured adults in the US.

OBJECTIVES: This study evaluates the burden of concomitant chronic obstructive pulmonary disease (COPD) + asthma, two highly prevalent and costly conditions. PATIENTS AND METHODS: The authors identified commercial enrollees from a large health plan database who were aged > or =40 years with medical and pharmacy benefits and medical claims with diagnosis codes for COPD or asthma between January 1, 2004 and December 31, 2004. We assigned patients to COPD or COPD + asthma cohorts, excluding all others. A patient index date was the first evidence date of COPD or COPD + asthma. We excluded those with one outpatient COPD or asthma claim or who were not continuously enrolled during the 12 months before and after index date. After controlling for differences, postindex respiratory-related emergency department (ED) visits and/or hospitalizations and costs were compared between cohorts.
RESULTS: We identified 24,935 patients, 17,394 (70%) in the COPD cohort and 7,541 (30%) in the COPD + asthma cohort. COPD + asthma patients were younger (58 versus 60 years; p < 0.0001) and more were females (62% vs 45%; p < 0.0001). COPD + asthma patients were 1.6 times more likely to have respiratory-related EDs and/or hospitalizations than COPD patients (95% CI 1.5, 1.8), and had $1987 (SE = $174, p < 0.0001) more respiratory-related healthcare costs. Mean adjusted respiratory-related healthcare costs were $3803 for COPD and $5790 for COPD + asthma. Limitations include a potential for misclassification due to misdiagnosis or coding errors as well as traditional biases of observational studies including the potential for omitted variable bias.
CONCLUSION: COPD + asthma patients are more costly and use more services than those with COPD, and may be more unstable and require more intensive treatment.