Incidence of and Risk factors for occupational injury among transit bus operators

Abstract

Driving a bus, professionally, is recognized as a high-risk occupation. This particular occupation has long working hours, irregular schedules, and lack of scheduled time for breaks and meals. Studies have shown professional bus operators have a high risk of cardiovascular disease, hypertension, gastrointestinal disorders and musculoskeletal problems, as well as psychological health issues, including fatigue, depression and anxiety. Based on Karasek's psychological demands/decision model, all of the working characteristics for bus operators result in high workload demand and low job control. Stress is reported as a main risk factor that leads to adverse health outcomes among professional drivers, especially cardiovascular disease and gastrointestinal disorders. Another serious stressor is the risk of violent acts. Bus operators are at potential risk of exposure to work-related violence as part of the requirement to interact with passengers. Numerous studies focused on bus operators' occupational diseases have provided a basic understanding for this study. Thus, the objective of this study was to provide a more comprehensive understanding of the magnitude, potential risk factors, and protective factors that may be associated with occupational injuries (both unintentional and intentional injuries) among bus operators and can serve as a basis for possible intervention strategies to reduce injuries.Demographic, work-related, and injury information was obtained from a transit company for a five-year period (Dec 1, 2006 to Dec 31, 2011). These data included the bus operators' demographic information: gender and age; work-related characteristics: years of working; job classification (part-time or full-time); working hours per day; driving hours per day; overtime hours per day; bus garage division; work start time; shift schedule; number of busses driven per day; and bus route types. Injury event reports included type of injury and body part(s) affected. Estimates of rates, per 100 Full Time Equivalents (FTEs), and associated 95% Confidence Intervals (C.I.), were generated using generalized estimating equations (GEEs) with exchangeable working correlation matrices. Adjusted Hazard Ratios (HRs), with associated 95% C.I., were generated, using Cox Proportional Hazards models. A total of 2,095 bus operators was included in this study. The overall unintentional injury rate with 95% C.I. was 17.8 (16.1-19.7) per 100 FTEs. Multivariable analysis identified increased risks for operators who: were female, compared to male (HR=2.4; 2.0-2.8); worked less than seven, compared to seven to less than 12 hours per day (HR=4.6; 3.8-5.5); and drove less than seven compared to seven to less than 12 hours per day (HR=3.2; 2.7-3.8). Operators who worked split, versus straight shifts, demonstrated a suggestive increased risk (HR=1.2; 1.0-1.4). Bus operators also tended to have an increased risk when driving limited versus regular bus routes (HR=1.36; 1.0-1.8). For intentional injury, the overall injury rate with 95% C.I. was 1.4 (1.1-1.7) per 100 FTEs. Operators who commenced working between 3 p.m. and 6 p.m. (HR=2.4; 1.2-5.1) and 12 a.m. and 3 a.m. (HR=5.3; 1.6-18.2), had higher risks of intentional injury, compared to those who commenced work between 9 a.m. and 12 p.m. In addition, higher risks were also found for operators who: worked less than seven or more than 12 hours (HR=16.3; 9.5-28.1 and HR=9.6; 3.7-23.5, respectively), compared to seven to less than 12 hours; drove less than seven hours or more than 12 hours (HR=11.3; 6.6-19.5 and HR=11.9; 4.8-29.6, respectively), compared to seven to less than 12 hours. Moreover, those who worked overtime had 30% higher risks, compared to those who did not.Results of this study serve as a basis for further studies and can inform the development of targeted intervention strategies to reduce occupational injuries relevant to bus operators.