P128 Whole-body vibration among mining heavy-vehicle operators is associated with back pain-related absenteeism. (1st September 2016) - Barrero, Lope H
Abstract : Background: Whole body vibration (WBV) has been related to back pain in professional vehicle operators; however, more evidence is needed to better establish the direct link between WBV exposure and back pain-related absenteeism. Aim: We tested the association between WBV exposure and absenteeism in a population of mining heavy equipment vehicle (HEV) operators who used an array of different HEVs using several vibration exposure estimates. Methods: The database analysed here included 3 years of absenteeism and vehicle operation logs for 2286 HEV operators. Workers' exposures per month were estimated from each worker's vehicle operation log and computing a time-weighted average of A(8), VDV(8) and Sed(8) vibration metrics from WBV directly measured on 11 different types of HEVs in the fleet. These three metrics captured average, shock and static compressive dose of the spine, respectively. Box-Cox regression models tested associations between the different vibration exposure estimates to time-to-absenteeism related to ICD-10 codes 50, 51 and 54, while adjusting for age, seniority, Body Mass Index and exposure duration. Results: WBV was positively and significantly associated to absenteeism; however, those associations exist only when exposure duration is included in the models, which is itself not statistically significant in the models. Hazard ratios varied greatly depending on the used exposure metrics (1.02 to 300, 000). Generally, exposures based on the A(8) metric, for the Z axis showed larger associations than the other parameters and exposure axes. Also, statistical models using time-varying exposures resulted in larger associations than models using cumulative metrics of exposure estimated to the time of absenteeism or to censoring. Discussion: WBV may be a determinant of back pain-related absenteeism and this undesirable effect is likely to occur after a few years of exposure. The evidence suggests that controls aiming at reducing WBV exposure would help directly reducing absenteeism in industry.