Improvement in bowel function was particularly marked in patients who switched from Oxy PR in the double-blind phase to OXN PR during the extension phase , resulting in a clinically meaningful reduction ( 12 points ) in BFI score : at the start of the extension phases , mean ( SD ) BFI score was 44.3 ( 28.13 ) , and was 29.8 ( 26.36 ) for patients who had received OXN PR in the double-blind phase .