Functional results -- including improvement of International Prostate Symptom Score ( IPSS ) , quality of life ( QOL ) , peak urinary flow , postvoiding residual urine volume , prostate-specific antigen ( PSA ) level , and prostate volume -- were assessed at 1 - , 3 - , 6 - , 12 - , and 24-month follow-up between January 20 , 2007 , and January 31 , 2012 .