© 2007 American Public Health Association DOI: 10.2105/AJPH.2006.086314
At the time of the study, all authors were with the Department of Public Health, Erasmus Medical Centre, University Medical Centre Rotterdam, Rotterdam, the Netherlands. Correspondence: Requests for reprints should be sent to Lintje Ho, MD, MPH, Department of Epidemiology and Biostatistics, Erasmus MC, University Medical Centre Rotterdam, PO Box 2040, 3000 CA Rotterdam, The Netherlands (e-mail: l.ho{at}erasmusmc.nl).
We studied differences in cause-specific mortality between highly integrated first- and second-generation Indonesians and native Dutch. We used the municipal population registers and cause-of-death registry to estimate rate ratios via Poisson regression analyses. Although overall mortality levels were similar, cause-of-death patterns varied between Indonesian migrants and native Dutch; the similar levels in overall mortality coincided with the high degree of integration of Indonesians within Dutch society. The differences in cause-of-death patterns may reflect persistent influences of country of origin and migration history.
Numerous studies have examined the relation between ethnicity, migration, and health status.1–3 Dutch studies have focused on socioeconomically less affluent Surinamese, Turkish, Moroccan, and Antillean/Aruban migrants, for whom large mortality differentials were observed.2,4–6 To our knowledge, we are the first to focus on Indonesians, who have largely integrated or even assimilated into Dutch society.7–12 Approximately 126000 Indonesians migrated to the Netherlands between 1945 and 1949 in the aftermath of World War II and the Indonesian War of Independence.13,14 Indonesians have adjusted to Dutch life (e.g., language and culture) smoothly; they have similar income levels to and are employed at equal rates in the government and in the education and health care fields as the native Dutch.7–12,15 Our objective was to assess whether Indonesians high degree of integration resulted in similar mortality levels and patterns as those of the native Dutch. Persisting mortality differences would indicate that genetic factors or persistent influences from the country of origin affect the health of migrants long after migration.
We compared overall and cause-specific mortality between first- and second-generation Indonesians and native Dutch. We used data from the cause-of-death registry and the municipal population registers. All Dutch inhabitants who died between 1995 and 2000 were included in our study, irrespective of whether death occurred in the Netherlands or abroad. Persons were considered to be first-generation Indonesian migrants if they and both parents were born in Indonesia and second-generation Indonesian migrants if they were born in the Netherlands but both parents were born in Indonesia. In our analyses, we excluded mixed Indo-Dutch persons and all Dutch inhabitants who were not native Dutch, except first- and second-generation Indonesians. We estimated the mortality rate ratios between Indonesians and native Dutch using Poisson regression analyses, and we controlled for 5-year age group, gender, marital status, and area-level socioeconomic status.
Compared with the native Dutch, first-generation Indonesian men and women had 7% lower (rate ratio [RR]=0.93; 95% confidence interval [CI]=0.90, 0.96) and 6% higher (RR=1.06; 95% CI=1.03, 1.09) mortality rates, respectively, whereas the second-generation men and women had 9% lower (RR=0.91; 95% CI=0.81, 1.03) and 11% higher (RR=1.11; 95% CI=0.98, 1.26) mortality, respectively (Table 1
Differences in cause-specific mortality between Indonesians and the native Dutch were substantial (Table 2
The "healthy migrant effect" probably does not play an important role in the cause-of-death pattern of persons of Indonesian descent in the Netherlands. On entry, Indonesians were not selected on their physical abilities for labor. Any health selection took place half a century ago; therefore, its effects must have been strongly reduced.16 Moreover, the small group who came more recently to the Netherlands did not show lower mortality than did those who migrated long ago. Selective remigration of an unhealthy subsample of migrants—the "salmon bias"17—is unlikely to have had much influence because Indonesian remigration is rare in the Netherlands.
Indonesians have lower mortality rates from most neoplasms, such as cancers of the gastrointestinal tract (Table 2 Poor living conditions in early life might have contributed to higher mortality for some diseases. Infection rates are relatively high in Indonesia. Acquired infections may persist for a lifetime.29,30 For first-generation Indonesians, this could explain the higher mortality from infections and consequently for liver cancer.31–35 The second generation, who grew up in the Netherlands, showed lower mortality from hepatitis than did the first generation. Vertical transmission might explain their higher hepatitis mortality rates compared with the native Dutch. Among Indonesians, a more prominent role of social control, support, and religion could explain lower mortality rates from alcohol-related deaths and suicide compared with the native Dutch, although religion could also explain higher rates of uterine cancer.36,37 Although Indonesians have similar levels of overall mortality, cause-specific mortality patterns vary considerably between Indonesians and the native Dutch. The differences in cause-of-death rates and patterns may be a result of persisting and often favorable influences of the country of origin on their social environment and health-related behaviors. Poorer living conditions in early life may, however, have contributed to excess mortality from some diseases. Thus, even though Indonesian migrants have achieved virtually the same chances of survival as have the native Dutch, their country of origin still influences their causes of death.
We thank Statistics Netherlands for the use of the data. We thank Joop Garssen and Johan Mackenbach for their comments on earlier drafts of this article.
Human Participant Protection
Peer Reviewed
Contributors Accepted for publication October 6, 2006.
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