Work injuries in internal migrants to Alberta, Canada. Do workers' compensation records provide an unbiased estimate...

It is not known whether out-of-province Canadians, who travel to Alberta for work, are at increased risk of occupational injury.

Workers' compensation board (WCB) claims in 2013 to 2015 for those injured in Alberta were extracted by home province. Denominator data, from Statistics Canada, indicated the numbers from Alberta and Newfoundland and Labrador (NL) employed in Alberta in 2012. Both datasets were stratified by industry, age, and gender. Logistic regression estimated the risk of a worker from NL making a WCB claim in 2013 or 2014, stratified by time lost from work. Bias from under-reporting was examined in responses to injury questions in a cohort of trades' workers across Canada and in a pilot study in Fort McMurray, Alberta.

Injury reporting rate in workers from NL was lower than those from Alberta, with a marked deficit (odds ratio [OR] = 0.17; 95% confidence interval [CI], 0.12-0.27) for injuries resulting in 1 to 30 days off work. Among the 1520 from Alberta in the trades' cohort, 327 participants reported 444 work injuries: 34.5% were reported to the WCB, rising to 69.4% in those treated by a physician. A total of 52 injuries in Alberta were recorded by 151 workers in the Fort McMurray cohort. In logistic regression, very similar factors predicted WCB reporting in the trades and Fort McMurray cohorts, but those from out-of-province or recently settled in Alberta were much less likely to report (OR = 0.02; 95% CI, 0.00-0.40).

Differential rates of under-reporting explain in part the overall low estimates of injuries in interprovincial workers but not the deficit in time-loss 1 to 30 days.