Table 5.

Subgroup analysis of infection within 2 years of age and the risk of allergic rhinitis

	No	OR (95%CI)	P	Heterogeneity
All studies	13	1.25 (1.12–1.40)	< 0.001	I2 = 89% P < 0.001
Cohort studies	6	1.17 (1.06–1.29)	0.001	I2 = 80% 0.002
Non-cohort studies	7	1.51 (1.13–2.02)	0.005	I2 = 93% P < 0.001
Outcome evaluation
Doctor's diagnosis	3	2.05 (0.96 -4.35)	0.06	I2 = 95% P < 0.001
Self-report	3	1.29 (0.81–2.08)	0.29	I2 = 70% 0.03
ISAAC	5	1.17 (1.06–1.30)	0.003	I2 = 77% 0.002
ISAAC + SPT	1	1.08 (0.78–1.49)	0.64	NA NA
Upper respiratory tract infection
All studies	7	1.32 (1.06–1.65)	0.01	I2 = 83%	P < 0.001
Cohort study	1	1.22 (1.05–1.41)	0.008	NA	NA
Non-cohort studies	6	1.37 (1.02–1.85)	0.02	I2 = 85%	P < 0.001
Bronchitis
All studies	3	0.98 (0.88–1.09)	0.74	I2 = 47%	0.15
Cohort studies	2	1.32 (0.87–2.00)	0.97	I2 = 41%	0.19
Case control study	1	0.96 (0.86–1.07)	0.46	NA	NA
Lower respiratory tract
All studies	5	1.16 (0.79–1.70)	0.46	I2 = 75%	0.003
Cohort studies	2	1.03 (0.63–1.68)	0.9	I2 = 0%	0.89
Non-cohort studies	3	1.24 (0.71–2.16)	0.45	I2 = 87%	0.003
Ear infection
All studies	5	1.06 (1.00–1.13)	0.06	I2 = 39%	0.16
Cohort studies	4	1.13 (1.04–1.22)	0.003	I2 = 0%	0.97
Case control study	1	0.96 (0.87–1.06)	0.42	NA	NA
Gastrointestinal infection
All studies	4	1.37 (1.01–1.86)	0.04	I2 = 91%	P < 0.001
Cohort study	1	1.20 (1.05–1.37)	0.007	NA	NA
Non-cohort studies	3	1.70 (0.95–3.06)	0.08	I2 = 94%	P < 0.001
Urinary tract infection
All studies	2	1.16 (0.83–1.63)	0.39	I2 = 70%	0.07
Cohort study	1	1.32 (1.23–1.41)	< 0.001	NA	NA
Case control study	1	0.92 (0.63–1.35)	0.67	NA	NA