Table 2.

Characteristics of the study population according to atopy: children (n 669) aged 4–11 years, Salvador, Bahia, Brazil, 1997–2005

		Skin reactivity (n 644)			IgE > 0·35 kU/l (n 635)
		Yes (n 204; 31·7 %)			Positive (n 321; 50·6 %)
Variable	Category	n	%	P value*	n	%	P value*
Sex	Male	125	35·5	0·022	191	55·4	0·008
	Female	79	27·1		130	44·8
Age (years)	≥6	133	32·0	0·785	209	50·9	0·838
	<6	71	31·0		112	50·0
Birth weight (g)	<3500	139	30·0	0·149	230	50·2	0·787
	≥3500	65	35·9		91	51·4
Duration of breast-feeding	Never	54	31·2	0·521	87	51·5	0·926
	<2 months	65	29·3		109	49·6
	≥2 months	85	34·1		125	50·8
No. of older siblings	None	86	34·5	0·215	122	50·2	0·891
	≥1	118	29·9		199	50·8
Parental asthma	No	177	31·8	0·829	277	50·5	0·903
	Yes	27	30·7		44	51·2
No. of children aged <5 years in the household	≤1	133	34·1	0·101	190	49·6	0·558
	>1	71	28·0		131	52·0
No. of persons per room	<2	164	35·0	0·003	238	51·6	0·378
	≥2	40	22·7		83	47·7
Maternal schooling	High school/university	52	43·0	0·012	70	57·4	0·164
	Secondary education	106	28·7		171	47·6
	Illiterate or primary	46	29·9		80	52·0
Smoking during pregnancy	No	183	32·0	0·570	287	51·0	0·548
	Yes	21	28·8		34	47·2
Mould in the house in the first year of life	No	78	28·6	0·146	125	46·1	0·054
	Yes	126	34·0		196	53·8
Household pets	Never had	109	35·2	0·067	156	50·6	0·962
	Has/had	95	28·4		165	50·5
Paved street	Yes	97	34·3	0·209	153	54·4	0·080
	No	107	29·6		168	47·5
BMI (Z-score)†	<−2	22	25·3	0·001	39	45·9	0·157
	≥−2 and <+1	142	29·9		234	49·8
	≥+1	40	48·8		48	60·0

Data are presented as number of cases (n) and prevalence (%).

*P value from χ ² test; significant P values indicated in bold font.

†BMI Z-score: <–2 = underweight; ≥−2 and <+1 = normal; ≥+1 = overweight/obesity.