Assessing the migrant mortality advantage among foreign-born and interprovincial migrants in Manitoba, Canada

Studies on mortality differentials between international immigrants and non-immigrants produced mixed results. The mortality of interprovincial migrants has been less studied. Our objectives were to compare mortality risk between international immigrants, interprovincial migrants, and long-term residents of the province of Manitoba, Canada, and identify factors associated with mortality among migrants.

We conducted a retrospective matched-cohort study to examine all-cause and premature mortality of 355,194 international immigrants, interprovincial migrants, and long-term Manitoba residents (118,398 in each group) between January 1985 and March 2019 using linked administrative databases. Poisson regression was used to estimate adjusted incidence rate ratios (aIRR) with 95% confidence intervals (CI).

The all-cause mortality risk of international immigrants (2.3 per 1000 person-years) and interprovincial migrants (4.4 per 1000) was lower than that of long-term Manitobans (5.6 per 1000) (aIRR: 0.43; 95% CI: 0.42, 0.45 and aIRR: 0.81; 95% CI: 0.80, 0.84, respectively). Compared with interprovincial migrants, international immigrants showed lower death risk (aIRR: 0.50; 95% CI: 0.47, 0.52). Similar trends were observed for premature mortality. Among international immigrants, higher mortality risk was observed for refugees, those from North America and Oceania, and those of low educational attainment. Among internal migrants, those from Eastern Canada had lower mortality risk than those migrating from Ontario and Western Canada.

Migrants had a mortality advantage over non-migrants, being stronger for international immigrants than for interprovincial migrants. Among the two migrant groups, there was heterogeneity in the mortality risk according to migrants' characteristics.