Formerly injured workers have higher risk of opioid-related harms than the general population in Ontario

North America continues to experience an opioid crisis. Between January 2016 and June 2023, Canada saw over 40,000 opioid-related deaths, and the United States saw about 500,000. Somewhere between 20 to 40 per cent of these deaths have occurred among working adults, leading researchers to investigate whether workplace factors may play a role. Work-related injuries or illnesses have been suggested as one potential risk factor, as injured workers may use opioids to cope with their symptoms. However, few studies have formally examined this relationship between work injury and opioid-related harms.

For this study, researchers examined opioid-related harms in a large group of Ontario workers who had previously experienced a work-related injury or illness. The harms identified in this study included poisonings, often referred to as overdoses, and mental and behavioural disorders (for example, dependence syndrome or withdrawal state).

The group of formerly injured workers for this study was drawn from the Occupational Disease Surveillance System (ODSS). The ODSS contains data on 1.7 million Ontario workers who had an accepted lost-time workers’ compensation claim for a work-related injury or illness between 1983 and 2019. These workers’ compensation data, which came from the Workplace Safety and Insurance Board (WSIB), included information about claimants' occupation and industry at the time they experienced their work-related injury or illness. This information was linked to health-care data to identify hospitalizations and emergency department visits for opioid-related harms that occurred from 2006 to 2020.

The team examined whether the number of opioid-related harms occurring among this group of formerly injured workers was similar to what would be expected if these workers experienced the same rate of opioid-related harms as individuals in the general population of Ontario aged 15 to 65.

To do this, they recorded the number of opioid-related poisonings and mental and behavioural disorders that occurred among workers between 2006 and 2020 and the length of time each worker was observed during that period. Individuals entered the ODSS when they made their first claim and were followed until they either had the opioid-related harm or until they died, moved out of Ontario, reached retirement age (65 years) or the follow-up period ended (in 2020).

The rates of harms in the general population over the same time period (2006-2020) were calculated using data from the Institute for Clinical and Evaluative Sciences, which included nine to 10 million Ontarians in each year of data collection.

Compared to the general population, between 2006 and 2020, opioid-related poisonings and mental and behavioural disorders were more likely to occur among the group of formerly injured workers. For opioid-related poisonings, the risk of emergency department visits was 2.4 times higher, and hospitalizations 1.5 times higher than the general population

For opioid-related mental and behavioural disorders, the risk of emergency department visits was almost twice as high, and hospitalizations 1.4 times as high among this group of formerly injured workers compared to the general population.

All industries and almost all occupation groups in the ODSS had elevated risks of opioid-related poisonings. Compared to the general population, emergency department visits for poisonings among formerly injured workers were more than three times as high for those in construction, 2.8 times as high in materials handling, 2.7 times as high in mineral, metal or chemical processing, and 2.6 times as high in machine-related occupations. Hospitalizations were twice as high for those in processing, and almost twice as high in construction and transport equipment operating occupations, among others.

Similar to poisonings, all industries and almost all occupational groups in the ODSS had higher risks of opioid-related mental and behavioural disorders than the general population. Emergency department visits were 2.7 times as high for materials handling, 2.5 times as high for construction, and twice as high for farming occupations, processing, and machine-related occupations. Hospitalizations were twice as high in construction and 1.6 times as high in processing and materials handling occupations.

These findings provide additional evidence that work-related injuries are a risk factor for opioid-related harms; and as such, they underscore the need for injury prevention. Workers may be more vulnerable to experiencing opioid-related harms after a work-related injury due to varying challenges they may face, including pressure to return to work, or lack of suitable workplace accommodations for their condition. These and other challenges may increase the likelihood that injured workers could use opioids to manage their pain, which could persist long after the injury first occurred.

After an injury, additional strategies to prevent work disability and long-term opioid use may include exercising caution when prescribing opioids, improving workers’ access to non-opioid treatments and mental health supports, and providing robust supports to help injured workers in their recovery and return-to-work experiences.

This study also showed that workers in certain industries and occupations may be especially at risk of opioid-related harms.

This study is one of the few to examine the role of work-related injury in opioid-related harms, and to further examine this data by industry and occupation in a large group of workers. Also, while most research on this topic has focused on opioid-related deaths, this research expands the scope to include emergency department visits and hospitalizations.

Some limitations of this study are that cases of opioid harms may not have been captured if the workers did not go to the hospital, or if they did not file a claim with the WSIB. Additionally, since workers’ occupations were recorded at the time they filed the claim that got them into the ODSS, information on occupation and industry may not accurately capture the occupation information at the time of harm, for example, if workers later changed jobs.