Spirometry for COPD Evaluation May Be Severely Underutilized

Key Point

Less than one-third of COPD patients from five health plans underwent spirometry testing following their new diagnosis, and the rate of testing decreased with patient age. In those patients who did receive spirometric assessment, less than half also underwent postbronchodilator testing, which is required for a formal diagnosis of COPD.

Spirometry testing is a widely accepted and encouraged diagnostic method for COPD, but new research shows that it is not used nearly enough. The study appears in the August issue of Chest and reports that only one-third of study participants with a COPD diagnosis have ever received spirometry testing.

“Without proper testing, both underdiagnosis and misdiagnosis may occur, which can lead to improper therapies being prescribed,” said lead author MeiLan Han, MD, in a released statement. “This study shows that we have a lot of work ahead of us in terms of raising awareness among both patients and physicians.” Dr. Han is from the Division of Pulmonary and Critical Care Medicine at the University of Michigan in Ann Arbor.

Along with colleagues from Johns Hopkins University in Baltimore, the University of Washington in Seattle, and the National Committee for Quality Assurance in Washington, DC, Dr. Han identified patients with newly diagnosed COPD through data collected from five health plans. They examined patients ages 40 and older and determined if those with a new diagnosis of COPD had received spirometry in the preceding 720 days. Of the 5,039 eligible patients identified, 53% were female, and 65% were in the 40- to 64-year age range.

“The distribution of new diagnoses between the genders was relatively similar, although slightly more new diagnoses in women were seen,” with 0.36% of the women receiving a new diagnosis of COPD versus 0.34% of the men, stated the study authors. However, they noted that this may reflect women’s greater longevity—particularly in the Medicare and Medicaid populations, which had significantly more women with COPD than men.

Only 32% of patients had received spirometry testing, reported the researchers, and approximately 46% of patients had received follow-up bronchodilator testing to confirm their diagnosis. “By definition, COPD is characterized by air flow limitation that is not fully reversible,” asserted the authors. “As such, initial spirometric testing should include bronchodilator testing. Thus, less than half of the 32% of patients we reported who had undergone spirometry received a truly diagnostic test.”

The research team also noted that their findings contradict previous study results in which more than 70% of physicians reported using spirometry for establishing a COPD diagnosis, which may indicate “a difference between what physicians report and how they actually practice,” posited the study authors. Also of particular concern was that spirometry testing in patients ages 75 to 84 was performed 28.3% of the time, and in those 85 or older, 14.9% of the time; meanwhile, spirometry frequency for patients ages 40 to 74 ranged from 32.2% to 33%. Sex was also reported to be a factor, with slightly higher spirometry utilization in women than in men (33.5% vs 29.4%).

Data analysis that used International Classification of Diseases, Ninth Revision, codes to identify spirometric tests permitted “an assessment of patients for whom the health-care provider suspected COPD,” said the study authors. They noted that 25.06% of patients with a diagnosis of chronic bronchitis underwent spirometry, significantly less than the 32.79% of patients with all other diagnosis codes who received testing. “This emphasizes an important point that a smoker with chronic cough needs further evaluation with spirometry,” as it may be the first sign of COPD, or could be related to a separate common cause of cough, asserted the researchers.

The frequency of spirometry use did not differ significantly with regard to type of health insurance coverage: 32.1% in patients with commercial insurers, 31.4% in those with Medicaid, and 30.4% in those with Medicare. In addition, no significant differences were found between rates of usage by primary care providers versus specialists or by the length of time of a patient’s negative diagnostic history for COPD, with durations of 180, 360, 540, or 720 days.

The study authors noted that medications prescribed for COPD are expensive and are associated with adverse events; therefore, a correct diagnosis for COPD must be attained through spirometric testing. “In total, these data provide important insights into the diagnosis of COPD, and suggest that additional efforts need to be introduced to optimize spirometry utilization,” they concluded.            

Reference
Han MK, Kim MG, Mardon R, et al. Spirometry utilization for COPD: how do we measure up? Chest. 2007;132(2):403-409.

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