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:With the FDA’s 2009 decision to change the T-Spot cutoff for a positive result from six to eight spots [19,20], it actively weighed the sensitivityspecificity balance in the face of lower-prevalence TB in the US.
Category: