Predictors of response to tiotropium versus salmeterol in asthmatic adults. - Peters SP; Bleecker ER; Kunselman SJ; Icitovic N; Moore WC; Pascual R; Ameredes BT; Boushey HA; Calhoun WJ; Castro M; Cherniack RM; Craig T; et al. (The Journal of allergy and clinical immunology, 2013)