Table 4.

 Protective effect of antibiotics for common respiratory tract infections and number needed to treat to prevent one complication

Infection/adverse outcome (age group)	Adjusted odds ratio* (95% CI)	Number needed to treat (95% CI)	P value
URTI/pneumonia (all ages)	0.68 (0.58 to 0.79)	4407 (2905 to 9126)	<0.001
Otitis media/mastoiditis (all ages)	0.56 (0.37 to 0.86)	4064 (2393 to 13 456)	0.008
Sore throat/quinsy (all ages)	0.84 (0.73 to 0.97)	4300 (2522 to 14 586)	0.021
Chest infection/pneumonia (significant interaction between prescribing and age):
0-4 years	0.22 (0.17 to 0.27)	101 (85 to 125)	<0.001
5-15 years	0.18 (0.13 to 0.24)	96 (73 to 137)	<0.001
16-64 years	0.27 (0.23 to 0.32)	119 (105 to 136)	<0.001
≥65 years	0.35 (0.33 to 0.38)	39 (36 to 42)	<0.001

URTI=upper respiratory tract infection.

*Adjusted for age, sex, and social deprivation.