Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:, after 30 d or 12 mo) to be the outcome of interest.([9,12,25]) In our opinion, an adequate treatment result is achieved if patients not only survive the first year after hip fracture but also maintain their independence.
Category: