B29
Investigating the association between ethnicity and survival from breast cancer using routinely collected health data: challenges and potential solutions
Amy Downing1, David Forman1, Robert West1, James Thomas1, Gill Lawrence2, Mark Gilthorpe1
1University of Leeds, UK, 2West Midlands Cancer Intelligence Unit, Birmingham, UK
Background
Previous studies have reported differences in survival from breast cancer by ethnic group. Some of these studies have taken information on ethnicity from routinely collected data, such as Hospital Episode Statistics (HES). There are several problems associated with using ethnicity from HES data, such as multiple ethnicities being recorded for a single patient with multiple hospital visits and missing data. This study will investigate methods to overcome these problems in order to assess the relationship between ethnicity and survival from breast cancer.
Method
51,146 breast cancer patients diagnosed between 1996 and 2003 were identified from a linked cancer registry-HES dataset for two regions of the UK. Where multiple ethnicities were recorded a single ethnicity was allocated according to the last recorded and most popular code. Ethnicity was missing in 16% of the records. Multiple imputation of missing ethnicity using age, stage, deprivation and census area ethnic make-up as predictors was undertaken for the last recorded and most popular data. Survival analysis (up to end 2006) was carried out using the imputed datasets.
Results
Across the two regions, 97.2% of the patients with a known ethnicity were White, 1.6% were South Asian, 0.8% were Black and 0.4% were categorised as Other (Mixed/Chinese/Other). White women were older at diagnosis than the other groups, whilst Asian women had a higher proportion of early stage tumours. Using last recorded ethnicity, unadjusted survival was significantly higher in the Asian group compared to the White group (HR=0.81, 95%CI: 0.69-0.94). After adjustment for age group and stage this survival difference was no longer significant (HR=0.95, 95%CI: 0.81-1.10). The results were similar using most popular ethnicity.
Conclusion
Assessment of the association between breast cancer survival and ethnicity presents many challenges. Further work will investigate methods to use all available ethnicity information for each patient.
