424 Whole body vibration among professional bus drivers – evaluation of an intervention study to reduce low back pain

Introduction Bus drivers are exposed to whole body vibration (WBV) and postural stress, both risk factors for low back pain (LBP). The study aimed to (1) assess WBV exposure and (2) evaluate the effect of an intervention to reduce LBP. Methods Exposure to WBV was assessed by measuring vibration levels (i.e., weighted root mean square acceleration [Aw] and vibration dose value [VDV]) in nine buses. For the intervention study, a toolbox presentation including ergonomic and lifestyle advice and an exercise program was instructed interactively to bus drivers. Two questionnaires (pre– and post–intervention) were constructed based on the VIBRISKS questionnaire to evaluate the effect of the intervention on LBP prevalence and to assess associated risk factors (e.g., manual material handling, seating posture, and WBV). The bus drivers’ motivation to change driving behaviour was also evaluated. Results The vibration levels never exceeded the exposure limits [Aw: 1.15 m/s 2 , VDV: 21 m/s 1 .75 ]. Only in one bus, the Aw (0.56 m/s 2 ), were the levels slightly higher than the action limit [0.5 m/s 2 ]. Four buses had a VDV (9.56 m/s 1 .75 , 13.0 m/s 1 .75 , 10.7 m/s 1 .75 and 11.0 m/s 1 .75 ) that exceeded the action limit [9.1 m/s 1 .75 ]. Sixty and 47 bus drivers participated in the pre– and post–intervention, respectively. The prevalence of LBP in the previous seven days decreased significantly (p=0.02). The score on correct lifting techniques was a significant determinant (p=0.046) in predicting LBP in the previous seven days (OR=0.32, 95% CI: 0.10 to 0.98). There was a significant post–intervention increase in knowledge about correct seating posture (p=0.001), and 95.5% of the bus drivers were willing to maintain their behavioural change. Discussion WBV exposure should be frequently evaluated to maintain below action-limit levels. Although this study revealed a significant reduction in LBP prevalence in the previous seven days, further research is needed in a randomised controlled trial design.