Innovative 19-year follow-up study from IWH finds people with permanent impairment face higher risk of early death—especially those injured in younger years
Serious work-related injuries can raise the risk of mortality even for those who initially survive the incident. According to a new study by the Institute for Work & Health (IWH), people who are permanently impaired by work-related injury face a greater risk of dying early—a risk that remains more than a decade after the injury.
What’s more, counter to the expectation that young workers can more easily recover from a work-related injury, the study finds the highest jump in mortality risks are those faced by people who are permanently impaired following a work injury in their younger years.
For both men and women with a permanent work-related impairment, a crucial factor that predicts whether they die early is what we call ‘work disability’—the difficulty they face staying in the labour market, says IWH Associate Scientist Dr. Heather Scott-Marshall, who led the study published in the September/October issue of the Canadian Journal of Public Health.
Work disability, she explains, stems from the physical, psychological and emotional difficulties individuals experience coping with, or adapting to, an acquired impairment. These difficulties can affect their sense of self and create problems with social role functioning—e.g. how they fulfil their roles as a worker, spouse, parent and so on.
This, in turn, can affect their ability to re-enter the labour market after an injury and may compromise long-term employment success, says Scott-Marshall. Other key factors contributing to work disability include stigma and discrimination against workers with impairment, which have been shown to affect opportunities in the labour market.
Matching injured cases with 10 controls
Research shows between 18 and 28 per cent of serious injuries experienced by adults in Canada take place at work. One in 10 individuals who report a work injury experience some degree of permanent impairment.
This study by Scott-Marshall used an innovative technique to link a set of data kept by Statistics Canada with another database held by the Workplace Safety and Insurance Board, the workers’ compensation agency for Ontario. It took a sample of 19,000 Ontarians whose work-related injury left them permanently impaired, and followed their outcomes for up to 19 years.
To set up a comparison or control group, the study team paired each individual in the injured sample with up to 10 other people who did not experience a work injury but shared similar characteristics such as age, sex, place of residence (region), and income level (for each of the four years before the year of injury). All identifying information was removed.
The study found the overall rate of death in men with permanent impairments was 14 per cent compared to nine per cent in the non-injured control group, representing a 55-per-cent higher risk of mortality. For women, the death rate among those with permanent impairments was six per cent compared to four per cent in non-injured controls—a 50-per-cent higher risk of mortality.
These higher risks of death persisted even after controlling for multiple factors that can bear on risk of death. After taking factors such as age, income and marital status into account, the study found that impaired women still faced an almost 30-per-cent higher risk of dying during the follow-up period compared to their non-impaired counterparts. Among impaired men, after controlling for these factors, the risk of dying was still 22-per-cent higher.
Work disability was found to play a key role in this increased mortality risk. To gauge the extent of work disability among people with permanent impairments from work, the research team looked at how much they earned post-injury in relation to pre-injury earnings.
Comparing low versus high disability
The team found that women with a work-related permanent impairment who experienced no or low work disability (i.e. who earned at least 75 per cent of their pre-injury income) were 27 per cent less likely to die in the follow-up period than women with high work disability (those earning less than 25 per cent of their pre-injury income). Among men with impairments, those with no or low work disability were 38 per cent less likely to die than those with high work disability.
This higher risk of death showed up most starkly a decade or more following the injury, with the divergence in death rates between claimants and controls peaking after 13 years in women and after 15 years in men.
This suggests to us that the risk of dying from a disabling injury can persist for decades, says Scott-Marshall.
For both men and women, a disabling injury at a young age (25 to 39) meant a higher likelihood of premature death.
This again probably ties into work disability and the fact that younger people may have greater difficulty getting back to work, says Scott-Marshall.
It could be that people at a younger age are less established in the labour market when they got injured. Or maybe the type of work they do is more physical and less easy to go back to after the injury. These are only speculations for the time being, and further research will tell us more. Scott-Marshall’s study, entitled “Long-term mortality risk in individuals with permanent work-related impairment,” can be accessed at: http://journal.cpha.ca/index.php/cjph/article/view/4535.
Source: At Work, Issue 79, Winter 2015: Institute for Work & Health, Toronto