Notch polymorphisms associated with sensitivity of noise induced hearing loss among Chinese textile factory workers

Table 1 Demographic characteristics of study subjects

Variables	Cases (n = 535)		Controls (n = 535)		P
Variables	n	%	n	%	P
Age (years)
Mean ± SD	40.40 ± 6.26		40.20 ± 5.79		0.595^a
≤ 35	129	24.1	132	24.7	0.921^b
35–45	303	56.6	305	57.0
> 45	103	19.3	98	18.3
Sex
Male	496	92.7	496	92.7	1.000^b
Female	39	7.3	39	7.3
Tobacco use
Now	311	58.1	301	56.3	0.476^b
Ever	11	2.1	17	3.2
Never	213	39.8	217	40.6
Alcohol consumption
Now	219	40.9	223	41.7	0.761^b
Ever	9	1.7	12	2.2
Never	307	57.4	300	56.1
Duration of noise exposed work (years)
Mean ± SD	18.54 ± 7.52		17.99 ± 6.99		0.216^a
16	237	44.3	250	46.7	0.461^b
> 16	298	55.7	285	53.3
Noise exposure levels (dB)
Mean ± SD	87.06 ± 7.69		87.46 ± 7.41		0.382^a
85	243	45.4	232	44.4	0.392^b
85–92	105	19.6	95	18.7
> 92	187	35.0	208	36.9
High frequency hearing thresholds (dB)
Mean ± SD	35.69 ± 9.92		14.01 ± 4.16		< 0.001^a
26	56	10.5	535	100.0	< 0.001^b
> 26	479	89.5	0	0.0

ISSN: 1471-2350