Table 3. Time Interval of Chest Radiographs between Groups.

	Non-Pneumonia Group (n = 108)	Positive Conversion Group (n = 59)	Initial Pneumonia Group (n = 66)*	P
Symptom onset to initial radiograph (days)†	5 (3–6)	5 (3–7)	6 (4–9)	0.001
Interval between initial negative chest radiograph to positive conversion (days)	NA	4 (4–6)	NA	NA
Symptom onset to positive conversion (days)	NA	10 (7–12)	NA	NA
	All pneumonia group (n = 125)
Symptom onset to positive chest radiograph (days)	NA	8 (7–12)		NA

Data are presented as median (25–75th percentile). ^*Three patients not able to remember the date of symptom onset, ^†Significantly different between ‘initial pneumonia’ and ‘positive conversion group’ and between ‘initial pneumonia’ and ‘non-pneumonia group.’