Glutathione S-transferase, incense burning and asthma in children

Table 1– Selected characteristics of participants in the Taiwan Children Health Study

	With genotyping	All eligible participants
Subjects n	3764	5082
Demographic information
Males	1848 (49.1)	2464 (48.5)
Age yrs	12.26±0.50	12.42±0.65
Parental education^# yrs
≤12	2319 (62)	3201 (63.4)
13–15	740 (19.8)	964 (19.1)
≥16	679 (18.2)	884 (17.5)
Gestational age^#
≤37	335 (9.1)	461 (9.3)
>37	3342 (90.9)	4496 (90.7)
Parental asthma^#	114 (3.1)	140 (2.9)
Parental atopy^#	957 (26.4)	1263 (25.8)
Family income^# TWD
≤400000	1249 (35.8)	1777 (37.7)
400001–800000	1408 (40.4)	1853 (39.3)
≥810000	828 (23.8)	1080 (22.9)
Active smoking^#	26 (0.7)	37 (0.7)
Maternal smoking during pregnancy^#	146 (3.9)	198 (3.9)
ETS at home^#	1774 (47.4)	2471 (48.9)
Incense burning at home^#
Never	1326 (37.0)	1724 (35.8)
Less than daily	1021 (28.5)	1398 (29.0)
Daily	1237 (34.5)	1699 (35.2)
Respiratory outcomes^#
Asthma
Lifetime asthma	292 (7.8)	375 (7.4)
Current asthma	114 (3.1)	140 (2.9)
Medication use	96 (2.6)	123 (2.4)
Wheeze
Lifetime wheeze	449 (12.0)	586 (11.6)
Current wheeze	150 (4.0)	186 (3.7)
Nocturnal wheeze	82 (2.2)	109 (2.2)
Exercise wheeze	206 (5.5)	276 (5.5)

Data are presented as n (%) or mean±sd, unless otherwise stated. TWD: New Taiwan dollar; ETS: environmental tobacco smoke. ^#: number of subjects does not sum to total because of missing data.

Table 2– Effects of incense burning at home and glutathione S-transferase genotype on subcategories of asthma and wheeze

	Asthma			Wheeze
	Lifetime asthma	Current asthma	Medication use	Lifetime wheeze	Current wheeze	Nocturnal wheeze	Exercise wheeze
Incense burning	1.05 (0.80–1.36)	1.36 (1.01–2.00)	1.52 (1.02–2.42)	1.10 (0.88–1.37)	1.07 (0.75–1.53)	1.31 (0.8–2.14)	1.64 (1.18–2.28)
Frequency of incense burning^#
Never	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Less than daily	0.76 (0.54–1.07)	1.13 (0.70–1.83)	1.29 (0.72–2.30)	0.92 (0.70–1.21)	1.00 (0.64–1.56)	1.07 (0.58–2.01)	1.62 (1.09–2.41)
Daily	1.22 (0.90–1.64)	1.52 (0.99–2.34)	1.75 (1.03–2.96)	1.21 (0.94–1.55)	1.12 (0.74–1.70)	1.68 (0.97–2.93)	1.88 (1.29–2.74)
p-value for trend	0.20	0.05	0.03	0.13	0.60	0.06	0.001
*GSTT1* null	1.21 (0.95–1.56)	1.43 (1.00–2.04)	1.46 (1.01–2.22)	1.17 (0.95–1.44)	1.14 (0.81–1.60)	1.14 (0.72–1.79)	1.09 (0.81–1.47)
*GSTM1* null	0.87 (0.68–1.12)	0.89 (0.63–1.27)	0.84 (0.55–1.27)	0.98 (0.80–1.21)	0.91 (0.65–1.27)	0.73 (0.47–1.16)	0.90 (0.67–1.21)
**GSTP1^Ile/Ile**	1.18 (0.60–2.32)	0.89 (0.37–2.11)	0.72 (0.28–1.85)	0.96 (0.57–1.61)	0.83 (0.37–1.86)	1.21 (0.37–4)	1.76 (0.7–4.41)

Data are presented as odds ratios with 95% confidence intervals. Models are adjusted for age, sex, parental education, parental asthma, parental atopy, gestational age, city, maternal smoking during pregnancy and environmental tobacco smoke at home. ^#: average days of incense burning at home per month.

Table 3– Association between incense burning at home and GSTT1 genotype on subcategories of asthma and wheeze

Data are presented as odds ratios with 95% confidence intervals.^#: significant interaction; ^¶: models are adjusted for age, sex, parental education, parental asthma, parental atopy, gestational age, city, maternal smoking during pregnancy and environmental tobacco smoke at home.

Table 4– Association of frequency of incense burning at home on subcategories of asthma and wheeze by GSTT1 genotype

	GSTT1 present	GSTT1 null
Subjects n	1937	1801
Frequency of incense burning^#
Asthma
Lifetime asthma
Never	1.00	1.00
Less than daily	0.74 (0.45–1.21)	0.74 (0.45–1.22)
Daily	1.04 (0.66–1.63)	1.42 (0.94–2.13)
p-value for trend^¶	0.87	0.09
Current asthma
Never	1.00	1.00
Less than daily	1.22 (0.60–2.50)	1.05 (0.54–2.05)
Daily	1.37 (0.69–2.75)	1.78 (1.01–3.16)
p-value for trend^¶	0.37	0.04
Medication use
Never	1.00	1.00
Less than daily	1.22 (0.51–2.92)	1.35 (0.60–3.00)
Daily	1.37 (0.59–3.18)	2.26 (1.11–4.57)
p-value for trend^¶	0.47	0.02
Wheeze
Lifetime wheeze
Never	1.00	1.00
Less than daily	0.96 (0.65–1.41)	0.85 (0.57–1.26)
Daily	1.02 (0.70–1.49)	1.40 (1.00–1.98)
p-value for trend^¶	0.91	0.04
Current wheeze
Never	1.00	1.00
Less than daily	0.78 (0.40–1.50)	1.15 (0.62–2.14)
Daily	1.01 (0.55–1.87)	1.17 (0.65–2.11)
p-value for trend^¶	0.97	0.60
Nocturnal wheeze
Never	1.00	1.00
Less than daily	0.86 (0.38–1.96)	1.20 (0.45–3.23)
Daily	0.85 (0.37–1.95)	3.21 (1.41–7.30)
p-value for trend^¶	0.69	0.003
Exercise wheeze
Never	1.00	1.00
Less than daily	2.03 (1.16–3.54)	1.28 (0.71–2.31)
Daily	1.86 (1.06–3.28)	1.99 (1.18–3.35)
p-value for trend^¶	0.04	0.01

Data are presented as odds ratios with 95% confidence intervals, unless otherwise stated. Models are adjusted for age, sex, parental education, parental asthma, parental atopy, gestational age, city, maternal smoking during pregnancy and environmental tobacco smoke at home. ^#: average days of incense burning at home per month; ^¶: calculated by stratification with GSTT1 genotype.