A survey of occupational exposure to low back pain risk factors in UPS truck drivers

Occupational low back pain (LBP) remains a significant problem among truck drivers. This cohort has substantial exposure to a number of risk factors for LBP, which include physical (i.e., prolonged and constrained sitting, whole body vibration, infrequent manual material handling), personal (i.e., malnutrition, smoking, lack of exercise), and psychosocial (i.e., high levels of stress, low job satisfaction, poor mental health) factors. Exposure to such a diverse range of risk factors for LBP among truck drivers imposes a significant challenge for risk management strategies aimed at minimizing the level of exposures. Knowledge of the underlying mechanism(s) responsible for the development of LBP among this cohort can open new venues for managing this problem, via interventions that specifically target the underlying malfunctioning mechanism(s) rather than simply reducing generic risk factor exposures. This is particularly important where elimination or minimization of exposure to risk factors is not practical or yet possible. Our research goal is to explore several modifiable biomechanical pathways that could be exploited for biomedical interventions and that link the specific effects of exposure to LBP risk factors associated with truck driving with the development of LBP. Lab-based studies related to the effects of exposure to a variety of single LBP risk factors suggest changes in aspects of tissue mechanics that adversely affect lower back mechanical environment and risk of injury (e.g., due to reduced spinal stability). However, it is not clear if cumulative effects of random and prolonged exposure to an array of risk factors (i.e., a realistic exposure case for truck driving) on tissue mechanics would be similar to such lab-based findings. Exposure-induced changes in tissue mechanics depend on the level and duration of exposure and vary according to the risk factors. Whether these alterations in tissue mechanics add up or cancel each other's effects over the course of a typical work day is not known. Forcing an altered tissue response to spine equilibrium and stability, exposure-induced changes in tissue mechanics can substantially change loads in the lower back particularly under physically demanding activities. In a recent R21 submission (A0) to National Institute of Occupational Safety and Health (NIOSH), we proposed to quantify the diurnal changes in lower back tissue mechanics among truck drivers and to determine the resultant effects on mechanical loads experienced in their lower back tissues. Our central hypothesis was that diurnal exposure to LBP risk factors that are associated with truck driving change aspects of tissue mechanics such that when completing a given set of physical activities, higher mechanical loads are experienced in lower back tissues at the end of the workday vs. the beginning of the workday. These increases in mechanical loads were hypothesized to be due to exposure-induced changes in tissue mechanics that result in: 1) altered work methods (e.g., due to an altered sense of trunk position) and 2) reduced spinal stability (e.g., due to altered reflexive contributions to spinal stability).The main objective of this application is to compile preliminary data required to address reviewers' questions (see Appendix) about the proposed sample of population. In particular, reviewers have requested us to clearly describe our truck drivers sample and their daily exposure to occupational risk factor for LBP. With supports from Kentucky Injury Prevention Center and UPS Ohio Valley District, we plan to compile such required data by completing the following specific aims: Aim 1: Develop a survey for collection of occupational exposure associated with UPS truck driving. A focus group including PI, Dr. Terry Bunn (Director of Kentucky Injury Prevention Center), two UPS truck drivers, and a graduate research assistant will be formed to develop a survey for quantification of diurnal occupational exposure of UPS truck drivers. Communicating with members of the focus group and following two complete days of observation of UPS truck drivers at work, an initial survey will be developed by PI and the graduate student. This survey will be then finalized in a meeting wherein all members of the focus group will attend. Aim 2: Conduct the survey to collect information related to diurnal occupational exposure to LBP risk factors from local UPS drivers (n=20). The graduate research assistant will collect the survey information by interviewing twenty UPS truck drivers during a work shift. The survey and the summary of collected data will be included in the resubmission of the R21 proposal to NIOSH. Despite more than half a century of research efforts to quantify loads in the lower back (e.g., NIOSH lifting equation is >30 year old), no effort has been made to take into account exposure-induced changes in aspects of tissue mechanics when estimating loads in the lower back. Quantitative information related to cumulative changes in tissue mechanics associated with a daylong truck driving activities as well as their impact on tissue loads will enable the smart design and implementation of effective administrative (e.g., work-rest cycles), clinical (e.g., exercise and stretching), and engineering (e.g., ergonomics of driver cabin) interventions aimed at reducing LBP among truck drivers. The immediate outcome of this pilot project will be the generation of critical data for addressing the major critiques to our initial submission of the R21 proposal. However, the results of such a R21 project will serve to guide future prospective investigations (R01) on controlling LBP among truck drivers (long-term outcome).