Objective To explore how to effectively use the data of occupational health examination, control the confounding factors, and analyze the hearing loss of workers exposed to noise.
Methods The occupational health examination data of employees in a large automobile manufacturing enterprise in 2017 were collected. The noise-exposed group (n=1 279) and the administrative group(n=720) were matched with 1:1 nearest neighbor by propensity score method. The hearing abnormalities of the two groups before and after matching were compared.
Results The noise exposure level of the noise group was(82.94±9.27)dB(A). All 720 people in the administrative group completed the matching; Among 1 279 people in the noise-exposed group, 720 people were matched successfully and 559 people were not matched. There was significant difference in the employment time between the two groups before matching(P < 0.01), and there was no significant difference of basic information between the two groups after the propensity score matching(P > 0.1). Before matching, there were statistically significant differences between noise-exposed group and administrative group in hearing abnormality rate of right ear at 2 000 Hz, 3 000 Hz, 4 000 Hz, 6 000 Hz, and left ear at 2 000 Hz, 3 000 Hz, 4 000 Hz, 6 000 Hz (P < 0.05). After matching, there was no statistically significant difference in the hearing abnormality rate between the two groups at 2 000 Hz(P > 0.05).
Conclusions In the analysis of occupational health examination data, propensity score method can be used to match some basic data of the exposure group and the control group, so as to reduce bias and correctly assess adverse effect of exposure to occupational hazards.
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