Table 1.

Inclusion and exclusion criteria for stage 1 and 2 randomisation

	Stage 1 CXR versus CT	Stage 2 FAPP versus no FAPP (standard laboratory sputum analysis)
Inclusion criteria	Age ≥18 years	The clinician intends to treat the patient for HAP or a hospital-acquired respiratory tract infection (RTI)
	Suspected HAP (For the purposes of this study, HAP is defined as per the BTS and FDA definitions as pneumonia which develops 48 hours after an admission to the hospital for an alternative diagnosis; or a new presentation to hospital with pneumonia in a patient who has been discharged from an overnight stay in hospital within the last 10 days)	A sputum sample has been obtained before the second dose of antibiotics
Exclusion Criteria	Already received a CXR to confirm suspected HAP diagnosis	Following the CXR or CT, the clinician decides not to treat with antibiotics for either HAP or a hospital-acquired RTI
	Diagnosis or suspected diagnosis of ventilator-associated pneumonia
	Intention to palliate rather than cure
	Interventions cannot be completed before administration of the second antibiotic dose*
	Cannot be randomised to low-dose, non-contrast CT scan on clinical grounds, for example, strong suspicion of PE (a non-contrast, low-dose thoracic CT scan is an inappropriate test for a PE, and if it is high in the differential diagnosis, then tick yes here)
	Pregnancy (A urine pregnancy test is required as part of the routine care before a CXR or CT scan. If the test reveals the patient is pregnant, they will not be eligible for the study)
	Previous study participation (patients with second of third episodes of HAP will not be re-recruited)

*In the circumstance where a patient is diagnosed with HAP while receiving antibiotics for a non-respiratory infection (eg, UTI) if the HAP diagnosis leads to a change in the antibiotic prescription to cover the HAP, then that patient will be eligible for recruitment. However, if the diagnosis of HAP would not result in a change in antibiotic, then the patient is not eligible.