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This thesis is based on a population study conducted to explore ethnic inequalities in cardiovascular disease using Hospital Episode Statistics (HES). The Hospital Episode Statistics have significant potential for health studies for ethnic groups, due to the large number of events from minority ethnic groups, comprehensive clinical information, full England coverage and fine geographical scale. However, the percentage of Finished Consultant Episodes (FCEs) with invalid ethnicity codes is at a high level. This thesis starts by developing a record linkage method and a coding rate method to improve the data quality of ethnicity codes in the HES. This thesis then further examines ethnic inequalities in cardiovascular disease incidence in England at both national and local geographical scales. The patterns of ethnic inequalities in cardiovascular disease appear to have changed little in the last ten years. However, large variations of geographical relative risk of cardiovascular disease were observed for ethnicity-sex groups. The relationships between areal socioeconomic status measured at different geographical scales and ethnic inequalities in different types of cardiovascular disease were also explored. As there are very limited data on the mortality of minority ethnic groups in the UK, few studies have compared the incidence and outcome of cardiovascular disease from the same population. This thesis came up with some novel findings, for example, that people from minority ethnic groups, who generally have increased risk of cardiovascular disease incidence, have better cardiovascular disease survival than white people. The contribution of areal socioeconomic status, distance to treatment sites and cardiovascular disease severity and treatment to the ethnic inequalities in cardiovascular survival was examined. The relationships between socioeconomic status measured at different geographical scales and ethnic inequalities in cardiovascular disease severity and treatment were investigated in this thesis as well.

Increasing time trends in the recorded incidence of childhood cancer have been reported in many different settings. The extent to which these trends reflect real changes in incidence, rather than improvements in methods for diagnosis and registration, is controversial. Using data from the National Registry of Childhood Tumours (NRCT), this thesis investigates time trends in cancer diagnosed under age 15 in residents of Britain during 1966-2005 (54650 cases), and considers potential sources of artefact in detail. Several different methods are used to estimate completeness of NRCT registration. The history of methods for diagnosis and registration of childhood cancers in Britain is described, and predictions are made for effects on recorded incidence. For each of the 12 main diagnostic groups, Poisson regression is used to fit continuous time trends and ‘step’ models to the annual age-sex-standardised rates by year of birth and year of diagnosis. Age-specific rates by period, and quinquennial standardised rates for diagnostic subgroups, are shown graphically. For three broad groups (leukaemia, CNS tumours and other cancer), geographical variation is compared by period of diagnosis. The results of these analyses are discussed in relation to the predicted artefacts. The evidence for a positive association between affluence and recorded incidence of childhood leukaemia is briefly reviewed. A special form of diagnostic artefact, the ‘fatal infection’ hypothesis, is proposed as an explanation of both this association and the leukaemia time trend. This hypothesis is examined in a novel test based on clinical data. The recorded incidence of childhood cancer in Britain increased in each of 12 diagnostic groups during 1966-2005 (from 0.5% per year for bone cancer to 2.5% for hepatic cancer, with 0.7% for leukaemia). Evidence presented here suggests that these increases are probably artefacts of diagnosis and registration. The potential implications for epidemiological studies of childhood cancer should be considered.