Agreement Between Birthplace and Self-reported Ethnicity in a Population-based Mammography Service

Background: Ethnicity is associated with genetic, environmental, lifestyle and social constructs. Difficult todefine using a single variable, but strongly predictive of health outcomes and useful for planning healthcareservices, it is often lacking in administrative databases, necessitating the use of a surrogate measure. A potentialsurrogate for ethnicity is birthplace. Our aim was to measure the agreement between birthplace and ethnicityamong six major ethic groups as recorded at the population-based mammography service for British Columbia,Canada (BC).
Methods: We used records from the most-recent visits of women attending the ScreeningMammography Program of British Columbia to cross-tabulate women’s birthplaces and self-reported ethnicities,and separately considered results for the time periods 1990-1999 and 2000-2006. In general, we combined countriesaccording to the system adopted by the United Nations, and defined ethnic groups that correspond to the nationgroups. The analysis considered birthplaces and corresponding ethnicities for South Asia, East/Southeast Asia,North Europe, South Europe, East Europe, West Europe and all other nations combined. We used the kappastatistic to measure the concordance between self-reported ethnicity and birthplace.
Results: Except for the“Other” category, the most-common birthplace was East/Southeast Asia and the most-common ethnicity wasEast/Southeast Asian. The agreement between birthplace and self-reported ethnicity was poor overall, asevidenced by kappa scores of 0.22 in both 1990-1999 and 2000-2006. There was substantial agreement betweenethnicity and birthplace for South Asians, excellent agreement for East/Southeast Asians, but poor agreementfor Europeans.
Conclusion: Birthplace can be used as a surrogate for ethnicity amongst people with SouthAsian and East/Southeast Asian ethnicity in BC.