Province-wide surveillance study finds drop in MSDs between 2004 and 2011

Work-related musculoskeletal disorders appear to be on the decline in Ontario. That’s what findings from a comprehensive population-based surveillance study recently done by the Institute for Work & Health (IWH) would suggest.

The study, led by IWH president Dr. Cameron Mustard, tracks the occurrence of work-related musculoskeletal disorders (MSDs) over eight years between 2004 and 2011. It uses three independent population databases to take a count of work-related MSDs as reported by the total number of Ontarians active in the labour force in that time period—a sample of about six million.

What’s important about this study is that it drew on three different data sources,” says Mustard. “And because they vary somewhat in how they define work-related MSDs, there are differences in incidence estimates between the three data sources. But all three show a steady decline.

This finding supports what several other studies in industrialized countries such as Australia, the Netherlands, the United States and the United Kingdom have found. The study, which has been submitted for publication in the Scandinavian Journal of Work, Environment and Health, is the first surveillance study on work-related MSDs done in Canada in recent times.

Three data sources

One of the sources for the study was the claims records of Ontario’s workers’ compensation agency, the Workplace Safety and Insurance Board, which covers about 90 per cent of Ontario’s workforce. The second source were records of emergency room visits, called the National Ambulatory Care Reporting System (NACRS). Since 2000, the reporting of all emergency department visits to the NACRS has been mandatory in Ontario. Patients who come into the ER with a complaint are typically asked where the injury occurred. All non-traumatic MSD complaints marked as work-related were included in the study—about one million cases over the eight-year period.

The third source of data for this study was the Canadian Community Health Survey, a series of interview surveys conducted by Statistics Canada about every two years since 2001. The survey is given to a sample of all Canadians aged 12 years and over. From this sample, IWH researchers zeroed in on those who were in the labour force (those 15 or older who had worked in the previous 12 months), who said they experienced a repetitive strain injury serious enough to limit their normal activities in the previous 12 months, and whose injury was attributed to exposures at work.

Compelling numbers

Mustard’s team found a clear decline in work-related non-traumatic MSDs in all three datasets. Over eight years, the incidence rate declined by 16.2 per cent according to emergency room records, by 48.2 per cent according to lost-time compensation claims and by 40.3 per cent according to the StatsCan surveys.

Mustard cautions that the reductions seen in the three datasets aren’t necessarily proof that the incidence of MSDs are declining—though the numbers make for a compelling case. There are plausible reasons why reporting or diagnostic practices might have changed over time with each of the three sources.

For example, the way workers are accommodated might have changed, leading to lower instances of disability requiring wage replacement. The drop of MSD cases in the ER records might have been due to people seeking help for their MSDs at other medical care venues. And the decline in self-reported RSIs seen in the StatsCan surveys might have been due to a change in what people identify as the cause of their RSI.

“These are all possible explanations,” says Mustard. “But to be skeptical of an overall decline in MSD means that you’d have to believe that all these alternate explanations are occurring at the same time.

Mechanization may be a reason

So, if work-related MSDs are indeed declining, what might be the cause? Mustard notes that few Canadian jurisdictions have adopted regulatory standards concerning exposure to adverse biomechanical demands. He also notes that the research literature on the effectiveness of interventions—including work contributed by IWH—is a bit unclear.

Mustard suggests that the constant change and renewal in equipment and machinery that people use at work might have played a role. Think of how work has changed for the people who stock grocery shelves, assemble car parts or do curbside trash collection. There has been an overall reduction in lifting, pulling and reaching work. “Manual material handling is basically gone in many, many sectors,” he says. “To the extent that this has happened through a deliberate effort to reduce injury risk, we could say that the reduction in injuries reflects prevention efforts.”

He notes, though, that there’s not a lot of human factors research out there to test this observation. “In an ideal world, we would be documenting how new production processes are better than the old processes in terms of biomechanical demands,” says Mustard. “That’s the piece that’s missing. The data is telling us that something has changed, but we can’t easily document what that was.

Source: At Work, Issue 76, Spring 2014: Institute for Work & Health, Toronto