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:Patients
Adults expected to be on mechanical ventilation for C3 days were included if they had a clinical diagnosis of Gram-negative hospital-acquired pneumonia (diagnosed C48 h after hospital admission), VAP (diagnosed [48 h after intubation), or HCAP (pneumonia in patients with a recent stay in an acute or long-term care facility) [10]; had a clinical pulmonary infection score (CPIS) of C6 (as defined by Fartoukh et al. [11] excluding the microbiologic criteria therein); and at least one of four risk factors for Gram-negative multidrug-resistant organisms (hospital stay of at least 5 days or an HCAP diagnosis; antibiotic use in the past 2 weeks; and history of colonization or exposure to multidrug-resistant Gram-negative pathogens) [10].
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