Bronchial asthma among workers in Alexandria and its association with occupation, eosinophil count, total serum immunoglobulin E antibodies, and glutathione S-transferase genes polymorphism

Peer review under responsibility of Alexandria University Faculty of Medicine

Available online 23 June 2011

Figures & data

Figure 1 Captured gel image of Multiplex PCR genotyping assay for detection of GSTT1 and GSTM1 gene deletion using 2% agarose. The subjects were classified as either (+), when at least one specimen of the gene was detected, or (−) when they showed a null genotype. Examples; participant No.11 is GSTT1 (+) and GSTM1(−); participant No.12 is GSTT1(−) and GSTM1(−); and participant No.17 is GSTT1(−) and GSTM1(+).

Table 1 Personal and occupational characteristics of workers with bronchial asthma and controls.

Characteristics	Workers with BA (n = 100)	Controls (n = 100)	Test of sig. P-value
Age
Min–max	40–76	41–70	t = 1.40 0.16
X ± SD	59.00 ± 11.03	57.16 ± 7.04
Height (m)
Min–max	1.57–1.89	1.56–1.97	t = −1.11 0.26
X ± SD	1.70 ± 0.11	1.86 ± 0.50
Weight (kg)
Min–Max	59.00–91.00	57.00–98.00	t = −1.17 0.24
X ± SD	74.95 ± 8.77	76.44 ± 9.12
BMI
Min–Max	18.62–47.00	18.01–36.16	t = 0.57 0.56
X ± SD	26.41 ± 6.50	25.93 ± 5.10
Education
Illiterate	40	32	X^2 = 13.08 0.01
Read & write	18	18
Basic	36	28
Secondary	–	8
University	6	14
Smoking habit
Non-smoker	47	61	X^2 = 1.19 0.08
Ex-smoker	53	39
Duration of employment (year)
Min–Max	20.00–45.00	19.00–38.00	t = −1.37 0.17
X ± SD	25.22 ± 9.46	26.67 ± 4.67
Daily working hours (h)
Min–Max	6.00–14.00	8.00–12.00	t = −1.34 0.18
X ± SD	9.16 ± 1.97	9.52 ± 1.82
Working status
Actually working	40	41	X^2 = 0.08 0.77
On pension	60	59
Use of PPE
Yes	16	26	X^2 = 3.01 0.08
No	84	73

BA: Bronchial asthma.

Table 2 Distribution of workers with bronchial asthma and controls according to exposure.

Nature of exposure	Workers with BA (n = 100)	Controls (n = 100)	Odds ratio	Test of sig. P-value
Not exposed^a	14	36	3.46 (1.64–7.38)	X^2 = 12.90 0.00
Exposed	86	64
Irritants	22 25.58%	13 20.31%	4.35 (1.58–12.25)	X^2 = 10.25 0.001
High molecular weight allergens (HMW allergens)^b	14 16.27%	11 17.18%	3.27 (1.08–10.13)	X^2 = 5.59 0.018
Low molecular weight allergens (LMW allergens)^c	26 30.23%	22 34.37%	3.04 (1.21–7.7)	X^2 = 6.94 0.008
Mixed environment (HMW and LMW allergens)	24 27.90%	18 28.12%	3.43 (1.32–9.01)	X^2 = 8.0 0.005

BA: Bronchial asthma.

a Unlikely to be exposed to substances associated with risk of asthma or to other irritating chemicals.

b High molecular weight such as allergens derived from animals (rodents, livestock, fish, shellfish, arthropods or mites); allergens derived from plants (latex, flour) or biological enzymes.

c Low molecular weight allergens such as highly reactive chemicals, isocyanates, sensitizing drugs, industrial cleaning agents, wood dusts, or metal sensitizers.

Table 3 Mean values and mean percent predicted values of post-bronchodilator (Post-BD) FEV₁, FVC and FEV₁/FVC in workers with bronchial asthma and controls.

Post-BD	Workers with BA (n = 100) X ± SD	Controls (n = 100) X ± SD	Test of sig. P-value
Post-BD FEV1 (L)	2.44 ± 0.19	4.12 ± 0.18	t = −81.78 0.00
Post-BD FEV1 (% predicted)	75.15 ± 6.80	89.66 ± 4.75	t = −17.48 0.00
FEV1Absolute change (L)	0.42 ± 0.18	0.05 ± 0.14	t = 16.93 0.00
FEV1% change from initial	20.64 ± 9.02	2.32 ± 1.11	t = 20.14 0.00
FEV1% change from predicted	12.77 ± 5.31	2.03 ± 0.93	t = 19.90 0.00
Post-BD FVC (L)	3.58 ± 0.19	4.95 ± 0.15	t = −56.10 0.00
Post-BD FVC (% predicted)	90.53 ± 2.94	90.51 ± 4.44	t = 0.033 0.97
FVC absolute change (L)	0.37 ± 0.12	−0.80 ± 0.26	t = 26.84 0.00
FVC% change from initial	11.58 ± 4.53	1.82 ± 1.27	t = 24.77 0.00
FVC% change from predicted	9.37 ± 3.10	2.03 ± 0.81	t = 28.52 0.00
Post-BD FEV1/FVC%	68.12 ± 5.86	83.49 ± 3.37	t = −22.69 0.00
FEV1/FVC% mean change	4.66 ± 6.43	1.98 ± 1.23	Mann–Whitney = 3000 0.00
FEV1/FVC% change from predicted	5.30 ± 7.33	2.21 ± 1.39	Mann–Whitney = 3003 0.00

BA: Bronchial asthma.

Table 4 Eosinophil count and total serum IgE level among workers with bronchial asthma and controls.

Variable		Workers with BA (n = 50)		Controls (n = 50)		OR	95% CI	Tests of sig. P-value
		No.	%	No.	%
Eosinophil count (×10^3 cells/μL)	Normal	49	98	50	100	Cannot be calculated	NA	Yates corrected P = 1
	High	1	2	0	0
Total serum IgE level (IU/mL)	Normal	22	44	15	30	0.55	0.22–1.34	0.14
	High	28	56	35	70

Table 5 Eosinophil count and total serum IgE level in different bronchial asthma severity categories in workers with bronchial asthma.

Variable		Intermittent or mild persistent BA		Moderate or severe persistent BA		Tests of sig. P-value
		No.	%	No.	%
Eosinophil count (×10^3 cells/μL)	Normal	17	100	32	96.9	1.0^a
	High	0.00	0.00	1	3.03
Total serum IgE level (IU/mL)	Normal	7	41.2	15	45.45	1.0^a
	High	10	58.8	18	54.54

BA: Bronchial asthma.

a Fisher’s Exact test.

Table 6 Association between genotype profile and bronchial asthma phenotype.

Gene	Chromosomal location	Polymorphism	Genotype	Workers with BA (n = 50)	Controls (n = 50)	OR	95% CI	P-value
				No. (%)	No. (%)
GSTM1	1p13	Null allele	Null	29 (58%)	26 (52%)	0.78	0.33–1.86	0.54
			WT	21 (42%)	24 (48%)
GSTT1	22q11	Null allele	Null	12 (24%)	5 (10%)	0.35	0.1–1.21	0.06
			WT	38 (76%)	45 (90%)

BA: Bronchial asthma.

Table 7a Association between GSTM1 genotype profile and bronchial asthma phenotype among exposed workers with bronchial asthma and exposed controls.

Gene	Chromosomal location	Polymorphism	Genotype	Workers with BA (n = 40)	Controls (n = 31)	OR	95% CI	P-value
				No. (%)	No. (%)
GSTM1	1p13	Null allele	Null	23 (57.5%)	18 (58%)	0.97	0.37–2.52	0.96
			WT	17 (42.5%)	13 (41.9%)

BA: Bronchial asthma.

Table 7b Association between GSTM1 genotype profile and bronchial asthma phenotype among non-exposed workers with bronchial asthma and non-exposed controls.

Gene	Chromosomal location	Polymorphism	Genotype	Workers with BA (n = 10)	Controls (n = 19)	OR	95% CI	P-value
				No. (%)	No. (%)
GSTM1	1p13	Null allele	Null	6 (60%)	8 (42.1%)	2.06	0.43–9.80	0.35
			WT	4 (40%)	11 (57.8%)

BA: Bronchial asthma.

Table 8a Association between GSTT1 genotype profile and bronchial asthma phenotype among exposed workers with bronchial asthma and exposed controls.

Gene	Chromosomal location	Polymorphism	Genotype	Workers with BA (n = 40)	Controls (n = 31)	OR	95% CI	P-value
				No. (%)	No. %
GSTT1	22q11	Null allele	Null	8 (20%)	3 (9.67%)	2.33	0.56–9.65	0.23
			WT	32 (80%)	28 (90.32%)

BA: Bronchial asthma.

Table 8b Association between GSTM1 genotype profile and bronchial asthma phenotype among non-exposed workers with bronchial asthma and non-exposed controls.

Gene	Chromosomal location	Polymorphism	Genotype	Workers with BA (n = 10)	Controls (n = 19)	OR	95%CI	P-value
				No. (%)	No. %
GSTT1	22q11	Null allele	Null	3 (30%)	2 (10.5%)	3.64	0.49–26.7	0.18
			WT	7 (70%)	17 (89.4%)

BA: Bronchial asthma.

Table 9 Association between combined GSTM1/T1 Null-genotype and bronchial asthma phenotype.

GSTM1 and GSTT1 genotype	Workers with BA (n = 50)	Controls (n = 50)	OR	95% CI	P-value
GSTM Null and GSTT1 Null-genotype	10 (20%)	3 (6%)	3.92	0.9–19.4	0.037
GSTM1 WT and GSTT1 WT-genotype	20 (40%)	22 (44%)	0.78	0.32–1.87	0.542
GSTM1 Null and GSTT1 WT-genotype	19 (38%)	23 (46%)	0.72	0.3–1.72	0.418
GSTM1 WT and GSTT1 Null-genotype	1 (2%)	2 (4%)	1.0	0.1–10.47	1.0^a

BA: Bronchial asthma.

a Fisher’s Exact test.

Figure 2 Correlation between total serum IgE level and pre-bronchodilator FEV₁/FVC% among workers with bronchial asthma.

Figure 3 Correlation between eosinophil count and total serum IgE level among workers with bronchial asthma.

Table 10 Association between GSTM1 genotype and post-bronchodilator (Post-BD) change in lung function indices among workers with bronchial asthma.

Lung function indices	GSTM1 genotyping (Null alleles) (n = 50)		Mann–Whitney test P-value
	Null (n = 29)	WT (n = 21)
	X ± SD	X ± SD
FEV1 Absolute change (L)	0.40 ± 0.16	0.44 ± 0.22	0.29
FEV1% change from initial	20.13 ± 8.73	21.66 ± 9.72	0.302
FEV1% change from predicted	12.66 ± 5.30	13.20 ± 5.59	0.381
FVC Absolute change (L)	0.38 ± 0.11	0.37 ± 0.15	0.821
FVC% change from initial	12.23 ± 3.83	11.46 ± 5.71	0.497
FVC% change from predicted	9.76 ± 2.82	9.39 ± 3.75	0.768
FEV1/FVC% mean change	4.41 ± 5.66	5.63 ± 7.32	0.26
FEV1/FVC% change from predicted	4.94 ± 6.51	6.51 ± 8.59	0.15

Table 11 Association between GSTT1 genotype and post-bronchodilator (Post-BD) change in lung function indices among workers with bronchial asthma.

Lung function indices	GSTT1 genotyping (Null alleles) (n = 50)		Mann–Whitney test P-value
	Null (n = 11)	WT (n = 39)
	X ± SD	X ± SD
FEV1 absolute change (L)	0.51 ± 0.10	0.39 ± 0.20	0.15
FEV1% change from initial	26.09 ± 6.07	19.28 ± 9.30	0.07
FEV1% change from predicted	16.10 ± 3.12	11.98 ± 5.56	0.116
FVC Absolute change (L)	0.34 ± 6.44	0.39 ± 0.14	0.23
FVC% change from initial	10.28 ± 3.63	12.37 ± 4.86	0.291
FVC% change from predicted	8.81 ± 1.47	9.83 ± 3.58	0.386
FEV1/FVC% mean change	8.37 ± 2.35	3.95 ± 6.81	0.08
FEV1/FVC% change from predicted	9.78 ± 3.45	4.42 ± 7.89	0.08