Prevalence and correlates of occupational noise-induced hearing loss among workers in the steel industry

Journal of the Egyptian Public Health Association

Table 4 Prevalence of hearing impairment and NIHL among noise-exposed (n = 396) and unexposed workers (n = 210) at two steel factories in Egypt, 2021

	Noise-exposed workers (n = 396)		Unexposed^{^} workers (n = 210)		OR^b (95% CI)	P value^a
	No.	%	No.	%	OR^b (95% CI)	P value^a
Right ear
Hearing impairment
No	45	11.4	59	28.1	3.04 (1.97, 4.69)	< 0.001^***
Yes	351	88.6	151	71.9	3.04 (1.97, 4.69)	< 0.001^***
Slight	347		147
Moderate	4		4
NIHL
No	213	53.8	195	92.9	11.16 (6.37, 19.57)	< 0.001^***
Yes	183	46.2	15	7.1	11.16 (6.37, 19.57)	< 0.001^***
Left ear
Hearing impairment
No	44	11.1	57	27.1	2.98 (1.92, 4.61)	< 0.001^***
Yes	352	88.8	153	72.8	2.98 (1.92, 4.61)	< 0.001^***
Slight	345		151
Moderate	6		2
Severe	1		0
NIHL
No	216	54.5	189	90.0	7.50 (4.58, 12.27)	< 0.001^***
Yes	180	45.5	21	10.0	7.50 (4.58, 12.27)	< 0.001^***
Binaural
Hearing impairment
No	114	28.8	114	54.3	2.93 (2.07, 4.16)	< 0.001^***
Yes	282	71.2	96	45.7	2.93 (2.07, 4.16)	< 0.001^***
NIHL
No	210	53.0	185	88.1	6.55 (4.13, 10.40)	< 0.001^***
Yes	186	47	25	11.9	6.55 (4.13, 10.40)	< 0.001^***

Abbreviations: NIHL Noise-induced hearing loss, OR Odds ratio, CI Confidence interval
Hearing impairment is categorized according to audiometric ISO value (average of values of hearing thresholds at 0.5, 1, 2, and 4 kHz) into slight (20–40 dB), moderate (41–60 dB), and severe impairment (61–80 dB)
NIHL is defined as a notch shown at 4 kHz (around 3 to 6 kHz), and threshold values at high-frequency substantially worse than threshold values at low frequency
^aChi-square test
^bUnivariate logistic regression was conducted to compute the odds of hearing impairment/NIHL (dependent variable) associated with noise exposure (independent variable)
^{^}Reference
^***p < 0.001