Differences between immigrants at various durations of residence and host population in all-cause mortality, Canada 1991–2006

Abstract

We used data from the 1991-2006 Canadian Census Mortality and Cancer Follow-up Study to compare all-cause mortality for immigrants with that of the Canadian-born population. The study addressed two related questions. First, do immigrants have a mortality advantage over the Canadian-born? Second, if immigrants have a mortality advantage, does it persist as their duration of residence increases? The analysis fitted sex-stratified hazard regression models for the overall sample and for selected countries of birth (UK, China, India, Philippines, and the Caribbean). Predictors were assessed at baseline. Mortality was lower among immigrants than the Canadian-born even after adjusting for a selected group of socio-demographic and socio-economic factors. The mortality differences persisted even after long residence in Canada, but appeared to be dependent on the age of the individual and the country of origin. Interpreted in light of known explanations of immigrant mortality advantage, the results mostly reflect selection effects.

Differences in all-cause mortality

“…Positive selection is likely to play a role in immigrants' survival advantage, as observed for refugees' mortality, which falls between that of hosts and other immigrants (Norredam et al (2012). This also concurs with recent findings suggesting that the survival advantage of immigrants may be attributed to the 'healthy migrant' effect and is less likely to result from the remigration of less healthy individuals (Norredam et al 2015;Omariba, Ng, and Vissandjee 2014).…”

“…The risk of dying increased with length of residence in a similar manner for older and younger immigrants. This pattern of mortality convergence concurs with studies by Nasseri and Moulton (2011) and Ng (2011), but differs from the results of Bos et al (2007) and Omariba, Ng, and Vissandjee (2014). Other studies have found age at migration to be an important factor (Angel et al 2010), thus suggesting that selection plays a more important role than acculturation.…”

“…The inclusion of sociodemographic characteristics lowered estimates of immigrants' death risk, in concordance with existing literature (Bos et al 2004;Klinthall and Lindstrom 2011;Norredam et al 2012;Omariba, Ng, and Vissandjee 2014;Wallace and Kulu 2014). In stepwise models the inclusion of education mattered most, followed by marital and parental status.…”

“…Selection could also be based on health status, but there are arguments for both directions of its effect (Argeseanu, Ruben, and Narayan 2008;Choi 2012;Kibele, Scholz, and Shkolnikov 2008;Ng 2011). The 'healthy migrant' hypothesis prevails (Omariba, Ng, and Vissandjee 2014;Wallace and Kulu 2014), suggesting a lower mortality for migrants that may be the result of a positive health self-selection (Buckely, Hofman, and Minagawa 2011). Primarily healthy people decide to migrate, especially if the reasons for migration relate to education or work (skilled and unskilled labor).…”

Trends, patterns, and differentials in Canadian mortality over nearly a century, 1921-2011

“…They are also often selected on characteristics that are associated with better health (e.g., higher education and income), and they sometimes have firmly established advantageous cultural behaviours (e.g., healthy diets and lifestyles). This is typically referred to as the "healthy immigrant effect" (Trovato 1985;Bourbeau 2002a;Omariba et al 2014).…”