Ins and Outs of COPD Bronchodilation

Responsiveness is consistent over the short term in individual patients but highly variable between patients.

Bronchodilator responsiveness in patients with chronic obstructive pulmonary disease (COPD) is a consistent variable over the short term in an individual patient but highly variable between patients.

Researchers used data from a 4-week, randomized, open-label, 2-period crossover study to investigate whether a patient’s reversibility treated as a continuous variable could predict his or her future response to 2 short-acting bronchodilators, albuterol and ipratropium, and help in future treatment decisions.

Patients received albuterol and then ipratropium 1 hour later or vice versa. During a second treatment period, the order of treatments was reversed. Predefined efficacy end points included pre- and post-bronchodilator forced expiratory volume in 1 second (FEV1).

For each patient, the researchers investigated the correlation coefficient between bronchodilator response on Days 1 and 10 and the correlation between treatment response on Day 1 and the mean treatment response on Days 5-10.

Bronchodilator response to albuterol on Day 1 was strongly correlated with the response on Day 10. A single measurement of the initial bronchodilator response to albuterol or ipratropium was highly correlated with the subsequent mean bronchodilator response over 5 to 10 days.

There was substantial variability of the FEV1 response to albuterol and ipratropium between patients, but the mean within-patient difference in response to albuterol or ipratropium between Days 1 and 10 was relatively small.

The results suggest that the short-term repeatability of bronchodilator reversibility tests is generally good, but the researchers cautioned that measuring a spirometric response may not accurately predict the likelihood of an individual patient achieving sustained benefit from bronchodilators. However, they suggested that accurate measures of bronchodilation may predict future response at the individual level over the short term.

The study was published on August 29 in the International Journal of Chronic Obstructive Pulmonary Disease.