Prevalence and management of cardiovascular risk factors in Portuguese living in Portugal and Portuguese who migrated to Switzerland

In agreement with previous reports [20], Portuguese living in Lausanne were more frequently male, were younger and had a lower educational level than Portuguese living in Porto. These differences can be explained by the fact that unemployment rates in Portugal are higher among younger and/or lower educated people [21], urging them to migrate in search of an employment. The higher prevalence of men among Portuguese migrants can be explained by the fact that in the majority of Portuguese couples, men migrate first in search of employment, the wife joining afterwards.

Both Portugal and Switzerland have universal health insurance coverage, but the degree of coverage varies. In Switzerland, health insurance is compulsory and insurance premiums are paid independently of income. The insured person pays part of the cost of treatment. Between 1999 and 2010, health insurance premiums increased by 77%, coupled with increasing out-of-pocket payments [22,23]. In Portugal, the health service is based on a universal system access to medical care, comprehensive and free, funded by taxation and complemented by public insurance funds and private and direct payments [24]. Contrary to Switzerland, where the choice of a doctor is free and multiple doctors are allowed, in Portugal, the choice the doctor is not allowed to patients, the waiting time before being received by a doctor is sometimes long, which is troublesome during a sudden illness [25,26]. Hence, obtaining an appointment might be easier in Switzerland than in Portugal, thus increasing the likelihood of diagnosing and adequately managing cardiovascular risk factors. Indeed, more than 90% of the Portuguese migrants in Switzerland have a personal doctor and adopt a more preventive behavior than the other migrant populations, which translates into a higher propensity to frequently change doctor and challenge the diagnoses proposed [20].

Contrary to a previous study that compared self-reported data [16], no differences were found between Portuguese migrants and Portuguese living in Porto regarding obesity levels. Similarly, no differences were found regarding the prevalence of hypertension, hypercholesterolemia and diabetes, suggesting that migration to Switzerland does not impact the prevalence of cardiovascular risk factors among Portuguese. These findings go against the “health migrant effect”, i.e. that subjects who migrate tend to be healthier than subjects who remained in their country or even healthier than natives of the host country [27]. Possible explanations include the high unemployment rate and hard living conditions in Portugal, which would have prompted unemployed subjects to migrate irrespective of their health condition; another explanation is that Portuguese migrants tend to live together and maintain their original dietary habits, which would sustain the prevalence of cardiovascular risk factors as in their country of origin. Previous [28] and on-going studies comparing the lifestyle behaviors (i.e. physical activity and diet) of Portuguese migrants, Portuguese residents and Swiss nationals will help a better assessment of the determinants of cardiovascular risk factors among Portuguese migrants.

Sixty-two out of the 74 obese Portuguese migrants in Switzerland (84%) indicated having been told by their doctor that they had excess weight, a value considerably higher than the 17% previously reported for Portugal [29]. Differences in awareness and management may also account for the the fact that hypercholesterolemic Portuguese subjects living in Porto were significantly less likely to be treated and controlled than their migrant counterparts. Although no significant differences were found regarding hypertension treatment and control, less than 4 out of 10 hypertensive participants were treated, and less than 4 out of 10 treated hypertensive participants were controlled. These values are lower than those previously reported in Switzerland [30], which may imply some degree of heterogeneity in hypertension management between Portuguese migrants in Lausanne and Swiss nationals. Portuguese migrants also tended to have a higher likelihood of being treated for diabetes than Portuguese residents, but no statistical significance was obtained due to the small sample size. Overall, our results suggest that Portuguese living in Lausanne have a similar cardiovascular risk factor profile and tend to be better managed regarding hypercholesterolemia than Portuguese living in Porto.

This study has several strengths: first, it used data from two population-based surveys and relied on objective standardized and validated measurements. Second, sensitivity analyses performed after excluding migrants living in Switzerland for less than 5 years did not change our main conclusions (Table 3). Hence, the differences between Portuguese residents and migrants might be attributable to changes in living environment rather than to unmeasured individual characteristics associated with migration.

This study has also several limitations worth acknowledging. First, our migrant sample includes individuals migrating from urban and rural areas, while the resident sample is mostly urban. Still, the rural exodus observed in Portugal in the 60s and 70s was directed to the two main urban centers, Porto and Lisbon [31] and approximately half of the Portuguese residents was born outside Porto (data not shown). These might reduce comparability issues regarding the urban or rural origin of the participants. Second, the fact that the interviews in CoLaus were conducted in French might have selected migrants with adequate knowledge of the language. Still, their socio-economic features are in agreement with other studies conducted among Portuguese migrants [20]. Third, the participation rate in the CoLaus study was relatively low, but comparable with the MONICA surveys conducted in Switzerland and in other countries [32]. This might have led to the selection of health-conscious subjects, which could partly explain the better management of lipid levels among Portuguese migrants. Fourth, the two studies were not conducted simultaneously, and new European guidelines for management of hypertension and for cardiovascular disease prevention were issued in 2003 [33,34], which could have changed cardiovascular risk factor management among Portuguese migrants. Still, Switzerland has its own guidelines regarding cardiovascular disease management, and it has been shown that Swiss doctors use guidelines from different sources in their clinical practice [35]. Thus, it is likely the impact of the European guidelines in cardiovascular disease management in Switzerland after 2003 might be modest. Finally, other factors might intervene regarding the prevalence and management of cardiovascular risk factors. Married subjects are more likely to attend health checks [36]; subjects with a lower income tend to forgo healthcare for economic reasons [22,23]. Unfortunately, no such data was available or collected using similar criteria in both studies. The ongoing follow-up of the CoLaus cohort will include more detailed familial and socio-economic data such as work history, income, and housing conditions (location, neighborhood, pollution and noise levels). Further, in Switzerland, regional differences in cardiovascular risk factor screening and management have been reported, so that migration to regions other than Vaud might lead to different results [37].