People with chronic obstructive pulmonary disease (COPD) breathe better when they add Spiriva to their other respiratory medications, a four-year study shows.

UCLA researcher Donald P. Tashkin, MD, and colleagues hoped for more. Their international study of nearly 6,000 COPD patients was designed to see whether long-term use of Spiriva could slow or even reverse the inexorable loss of lung function that is the hallmark of the disease.

That didn't happen, although there remains hope that treatment might slow loss of lung function in some as-yet unidentified subset of COPD patients. To date, the only thing that slows COPD is for a patient to quit smoking.

But Tashkin and his fellow study investigators did show that adding Spiriva to different classes of respiratory medications improved lung function, bettered , and cut the number of disease exacerbations (three days or more of coughing, , , and/or shortness of breath requiring or treatment).

"There were important lung-function benefits associated with [Spiriva] that were maintained during the four years," Tashkin and colleagues note. "[Spiriva] reduced respiratory -- including a decreased risk of -- and reduced mortality."

In an editorial accompanying the study, John J. Reilly, MD, of the University of Pittsburgh notes that there are various types of COPD. He suggests that different types of COPD may respond differently to treatment, so there may very well be a subgroup of patients for whom Spiriva and other treatments slows their loss of lung function.

Reilly urges investigators to identify meaningful COPD subtypes for future clinical studies.

Spiriva is an inhaled drug. Anticholinergic drugs keep the muscles around the large airways from tightening. Spiriva is the only long-acting member of this drug class approved in the U.S. Short-acting anticholinergic drugs include .

The study was funded by Spiriva makers Boehringer Ingelheim and Pfizer. Several study investigators have received financial support from these or other drug companies; three of the study investigators are employed by Boehringer Ingelheim.

The study and editorial appear in the Oct. 9 issue of The New England Journal of Medicine.

SOURCES: Tashkin, D.P. The New England Journal of Medicine, Oct. 9, 2008; vol 359: pp 1543-1554. Reilly, J.J. The New Engla nd Journal of Medicine, Oct. 9, 2008; vol 359: pp 1616-1618.