Osteoarthritis (OA) is a degenerative disease of joints and can affect knees, hips, shoulders, lower back and neck and the small joints of the fingers and toes. It is a chronic condition that causes pain, stiffness and activity limitations. The condition is prevalent, affecting 20 per cent of people over 45 years of age and as many as 60 per cent of people over the age of 60. Why some people develop the disease and others do not is unclear. In addition to age, factors associated with the development of OA include high body weight, high-intensity physical activity and injury.
There has been a long-standing interest in understanding the extent to which chronic exposure to work-related physical job demands may be involved in the development of OA. Much of the evidence concerning work exposures and OA is drawn from the field of epidemiology. Using this observational science discipline, researchers have measured the physical demands of work activities in a variety of occupations and followed workers over time to identify the onset of disease symptoms.
Research evidence that clearly establishes a link between an occupational exposure and the incidence of a health condition will typically lead to regulatory standards to eliminate or minimize the hazardous exposure. Clear evidence of causation also enables clarity and consistency in entitlement decisions in provincial workers’ compensation systems.
In the case of physical job demands and the development of OA, the research evidence is relatively extensive. At the same time, research studies in this area often do not use consistent methods to measure the intensity and duration of exposure and the definition of disease onset. As a result, it is difficult to clearly summarize the consistency and strength of the evidence for the role of occupational physical demands in the incidence or aggravation of osteoarthritis.
To get a clearer picture of the role of work activities in the development of OA, the British Columbia provincial worker’s compensation board, WorkSafeBC, commissioned a systematic review of individual research studies in this field. Dr. Craig Martin, manager of clinical services and chair of the Evidence-Based Practice Group at WorkSafeBC, reports that trying to understand the role of work in the development of OA is a daily occurrence. We felt our medical advisors needed a more coherent message to give to claims staff. That’s why we commissioned the systematic review.
WorkSafeBC a partner in review process
A team from the Institute for Work & Health (IWH) was selected to conduct the systematic review. The team screened nearly 450 articles, finally focusing on 69 good-quality scientific studies from 23 countries. Two thirds of these studies contained more than 500 people each. The review was comprehensive, examining the role of diverse job tasks like kneeling, lifting, work that involves vibration, grasping, sitting for long periods, standing and climbing in the development of OA in the knees, hips, hands, wrists, fingers, elbows, spine, shoulders, neck, ankles, feet and toes. The review also looked at work and OA for men and women separately.
Important to IWH’s review process was working with the team at WorkSafeBC. Working collaboratively is a key part of all IWH systematic reviews because it helps shape the review question, review process, and the audience-relevant messages coming out of the findings. This collaboration was just as important to stakeholders at WorkSafeBC. IWH understands what we do and why we ask these questions, and the discussions we have with IWH researchers are the best part [of working together on a systematic review],
says Martin. In fact, we factored into all our new systematic review requests for proposals that there must be two-way feedback, of the type we have been having with IWH for a long time.
IWH’s review of the research on the association between work and OA is one of the most comprehensive undertaken to date. The findings, the subject of a paper currently under peer review, were detailed in a report to WorkSafeBC. Notable was strong evidence of an association between kneeling, squatting and bending on the job and an increased risk of developing knee OA in both men and women, and strong or moderate evidence of an association between lifting or being exposed to vibration on the job and an increased risk of developing hip OA. Not all the findings were clear cut, so the report also provided recommendations for future research. These recommendations focused on the need for greater inclusion of women in studies, the need for more research on hands, spines, feet and multiple joints, and the need for studies to consistently assess the frequency, duration, and intensity of work tasks that may put workers at risk for the development of OA.
The findings of the review have provided important information that WorkSafeBC’s roughly 65 medical advisors use in working with claims staff to support adjudication decisions. According to Martin, this has contributed to more consistent decision-making.
We certainly don’t expect the answers to be black and white,
he says. Medical advisors are using the document and factoring it into the specifics of the case they’re looking at. Our medical advisors tell us that it’s helpful to have a science-based document to consult and take into consideration when dealing with each individual case.