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:Up to almost 70 percent of patients with NS-associated FSGS may attain complete or partial remission and maintain stable renal function for about 10 years when given a prolonged therapy with steroid or immunosuppressive drugs (19).
Category: