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:The presence of complications associated with IBD is also common as several patients report having fistulas, abscesses, arthritis and dermatological, ocular and gynaecological complaints (e.g. Levine and Burakoff, 2011).
Category: