The effect of COPD severity and study duration on exacerbation outcome in randomized controlled trials.
Eriksson G, Calverley PM, Jenkins CR, Anzueto AR, Make BJ, Lindberg M, Fager?s M, Postma DS. The effect of COPD severity and study duration on exacerbation outcome in randomized controlled trials. Int J Chron Obstruct Pulmon Dis. 2017; 12:1457-1468.