[The interaction of workplace noise, body mass index and systemic inflammatory response on hypertension]

Objective: To investigate the interaction of workplace noise, body mass index (BMI) and systemic inflammatory response on hypertension. Methods: In January 2019, 1124 male workers from an automobile factory in Wuhan were selected by cluster random sampling method. The study population was divided into normal body weight group (BMI<24 kg/m(2)) and overweight group (BMI≥24 kg/m(2)) according to BMI, and were followed up for 3 years. The occupational health examination of the workers was carried out every year, blood routine and blood biochemical indexes were collected, and the information of the workers' age, BMI, type of work and age of exposure to injury were collected through field questionnaires. The noise intensity of the workplace of the enterprise was measured for 3 consecutive years, and the equivalent sound level was calculated according to the working time. Normal and skewness measurements were described by Mean±SD and [M (Q(1), Q(3)) ], respectively. t-test or Wilcoxon rank sum test was used for inter-group comparisons. Categorical variables were expressed by frequency and percentage (%), and Chi-square test was used for inter-group comparisons. Mixed effects models and generalized estimation equations were fitted to analyze the relationship between occupational noise, systemic inflammation, and their interaction terms with blood pressure and hypertension risk. Results: Univariate analysis revealed that the white blood cell counts, neutrophil counts, lymphocyte counts and eosinophil counts were positively associated with systolic blood pressure and diastolic blood pressure in overweight group (n=467), respectively (P<0.05). The participants with white blood cell counts≥5.94×10(9)/L, neutrophil counts≥3.31×10(9)/L, lymphocyte counts ≥2.03×10(9)/L, and eosinophil counts ≥0.12×10(9)/L had increased risk of hypertension by 52% (RR=1.52, 95%CI: 1.11-2.05), 37% (RR=1.37, 95%CI: 1.01-1.83), 58% (RR=1.58, 95%CI: 1.18-2.09), and 52% (RR=1.52, 95%CI: 1.12-2.06), respectively (all P<0.05). Multivariate analysis found a positive association between BMI and the risk of hypertension in the overweight group (P<0.05), the participants with lymphocyte counts≥2.03×10(9)/L and eosinophil counts≥0.12×10(9)/L had increased risk of hypertension by 39% (RR=1.39, 95%CI: 1.01-1.89) and 46% (RR=1.46, 95%CI: 1.06-1.98), respectively (all P<0.05). There was no correlation between BMI and the risk of hypertension in normal weight group (P>0.05). The multiplicative interaction of occupational noise (≥80 dB) with white blood cell counts (≥5.94×10(9)/L) and lymphocyte counts (≥2.03×10(9)/L) increased the risk of hypertension by 100% (RR=2.00, 95%CI: 1.06-3.55) and 89% (RR=1.89, 95%CI: 1.01-3.32) (all P<0.05) in overweight group, respectively. Additionally, a significant additive interaction was observed between noise exposure (≥80 dB) and basophil counts (≥0.03×10(9)/L) on hypertension risk in the overweight group (RERI=0.49, 95%CI: 0.02-0.96, P<0.05) . Conclusion: The combined exposure of occupational noise and systemic inflammation may increase the risk of hypertension in overweight workers in automobile manufacturing plants, and the two have additive and multiplicative interactions.