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ATLANTA -- For patients with chronic obstructive pulmonary disease (COPD), their own assessment of breathing problems is more predictive of outcomes than spirometry or doctor-diagnosed exacerbations, a researcher said here.

Among 180 patients in an observational study, those reporting minimal symptoms tended to show similar scores on standard measures of physical functioning and activity, quality of life, and depression, irrespective of spirometry results and the number of exacerbations they experienced, according to Sandra Adams, MD, of the University of Texas Health Science Center in San Antonio.

At the same time, patients indicating severe breathing problems fared much worse on such outcomes, including those whose objective measures of disease severity suggested that they should feel relatively well.

"Perception of dyspnea in patients with COPD appears to be the main factor" driving clinical outcomes, she told attendees at the American College of Chest Physicians annual meeting.

The implication, Adams said, is that clinicians should rely on patients' subjective reports of dyspnea as much as on the more traditional measures of disease severity when making treatment plans.

In the preliminary analysis she reported here, covering the first 180 of a planned 375 patients, the cohort was divided into four groups according to patients' subjective reports of symptoms (minimal or severe), spirometry results (mild-to-moderate or severe), and exacerbations (few or many).

Definitions of these groups, and the percentages of the full cohort they represented, were as follows:

• A: minimal symptoms, mild-to-moderate spirometry and few exacerbations; 20%
• B: severe symptoms, mild-to-moderate spirometry and few exacerbations; 10%
• C: minimal symptoms, severe spirometry and/or many exacerbations; 22%
• D: severe symptoms, severe spirometry and/or many exacerbations; 48%

For purposes of this stratification, FEV1 (forced expiratory volume in 1 second) values of 50% or more of predicted levels were considered mild to moderate and "few" exacerbations meant they occurred no more frequently than once per year. Subjective symptoms were scored on the modified Medical Research Council (mMRC) scale.

Across the entire cohort, about three-quarters were male, the mean age was 67, and 40% were on supplemental oxygen. Patients with other lung diseases, uncompensated heart failure, systemic inflammatory diseases, cancers, dementia, or primarily psychotic disorders were excluded.

Clinical outcomes were assessed with standard instruments such as the Personal Health Questionnaire, the 6-minute walk test, and an ankle-worn actigraphy device.

Contrary to what would likely have been most clinicians' expectation, Adams said, scores on these instruments did not divide according to spirometry results and exacerbation frequency, but instead by mMRC scores.

For example, mean depression scores for groups A and C -- the ones with minimal subjective symptoms -- were 5.6 and 5.0, respectively, whereas for groups B and D, the means were 8.9 and 6.9, respectively.

Likewise, the actigraphy monitors showed mean step counts of 8,600 and 7,367 for groups A and C, respectively. For groups B and D, the corresponding counts were 4,842 and 4,825, respectively.

Patterns for the other outcome assessments were similar, Adams reported.

Neither spirometry nor exacerbation frequency were significant predictors of clinical outcome scores, Adams said. But the mMRC score was a significant predictor of these outcomes (P≤0.01).

Session co-moderator Allen Blaivas, DO, of the VA New Jersey Health System in East Orange, N.J., commented that the study was limited by the lack of a non-COPD control group.

"It's sort of intuitive that someone with more symptoms will be more limited in terms of physical activity and in the way they feel and their approach to life," he added.

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