Table 1 Representative studies of the effect of long acting bronchodilators in COPD.

Study	No of patients	Duration(years)	Mean FEV1(% predicted)	Comparison	Outcome
Rossi88	434	1	48%	Formoterol 12 μg twice daily v placebo	Mean % of days of additional treatment reduced from 8% to 4%. Percentage of patients receiving additional treatment for exacerbations reduced from 34% to 23%
Szafranski26	406	1	36%	Formoterol 12 μg twice daily v placebo	Reduced need to use >4 extra inhalations of reliever/day by 55%. No effect on severe exacerbations or use of oral steroids
Calverley27	511	1	36%	Formoterol 12 μg twice daily v placebo	No difference in time to first exacerbation, mean rate of exacerbations, and exacerbations requiring oral steroids
Brusasco89	807	0.5	39%	Salmeterol 50 μg twice daily v placebo	No difference in time to first exacerbation or exacerbation rate
Mahler72	341	0.5	41%	Salmeterol 50 μg twice daily v placebo	No difference in time to first treated moderate exacerbation
TRISTAN31	733	1	44%	Salmeterol 50 μg twice daily v placebo	20% reduction in exacerbation rate. 29% reduction in rate of exacerbations requiring oral steroids
Casaburi74	921	1	39%	Tiotropium 18 μg twice daily v placebo	Delay in time to first exacerbation. 20% reduction in exacerbations, 14% reduction in number of subjects exacerbating.
Brusasco89	802	0.5	39%	Tiotropium 18 μg twice daily v placebo	Delay in time to first exacerbation. Reduction in mild/moderate exacerbation rate