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:This series represents a very high risk group as lower body weight, multi-organ dysfunction syndrome, more severe PRISM scores, the need for greater inotropic support, and more severe fluid overload, are associated with increased risk of mortality for children receiving CRRT [3].
Category: