For group 1b , during the period in which the patients were receiving 4 and 8 mg doxazosin XL treatments ; the International Prostate Symptom Score changes were 1.3 and 3.6 ( P < .001 ) , the Q ( max ) changes were 1.6 and 3.2 mL/s ( P < .019 ) , and the QoL changes were 0.4 and 1.8 ( P < .001 ) in groups 1 and 2 , respectively .