Abstract: A multilevel model (allowing for individual risk factors and geo graphic context) is developed for jointly modelling cross-sectional differences in diabetes prevalence and trends in prevalence, and then adapted to provide geographically disaggregated diabetes prevalence forecasts. This involves a weighted binomial regression applied to US data from the Behavioral Risk Factor Surveillance System (BRFSS) survey, specifically totals of diagnosed diabetes cases, and populations at risk. Both cases and populations are dis aggregated according to survey year (2000 to 2010), individual risk factors (e.g., age, education), and contextual risk factors, namely US census division and the poverty level of the county of residence. The model includes a linear growth path in decadal time units, and forecasts are obtained by extending the growth path to future years. The trend component of the model controls for interacting influences (individual and contextual) on changing prevalence. Prevalence growth is found to be highest among younger adults, among males, and among those with high school education. There are also regional shifts, with a widening of the US “diabetes belt”.
Abstract: Progress towards government health targets for health areas may be assessed by short term extrapolation of recent trends. Often the observed longitudinal series for a set of health areas is relatively short and a parsimonious model is needed that is adapted to varying observed trajectories between areas. A forecasting model should also include spatial dependence between areas both in representing stable cross-sectional differences and in terms of changing incidence. A fully Bayesian spatio-temporal forecasting model is developed incorporating flexible but parsimonious time dependence while allowing spatial dependencies. An application involves conception rates to women aged under 18 in the 32 boroughs of London.
Abstract: Information regarding small area prevalence of chronic disease is important for public health strategy and resourcing equity. This paper develops a prevalence model taking account of survey and census data to derive small area prevalence estimates for diabetes. The application involves 32000 small area subdivisions (zip code census tracts) of the US, with the prevalence estimates taking account of information from the US-wide Behavioral Risk Factor Surveillance System (BRFSS) survey on population prevalence differentials by age, gender, ethnic group and education. The effects of such aspects of population composition on prevalence are widely recognized. However, the model also incorporates spatial or contextual influences via spatially structured effects for each US state; such contextual effects are allowed to differ between ethnic groups and other demographic categories using a multivariate spatial prior. A Bayesian estimation approach is used and analysis demonstrates the considerably improved fit of a fully specified compositional-contextual model as compared to simpler ‘standard’ approaches which are typically limited to age and area effects.
Abstract: Risks for many chronic diseases (coronary heart disease, can cer, mental illness, diabetes, asthma, etc) are strongly linked both to socio economic and ethnic group and so prevalence varies considerably between areas. Variations in prevalence are important in assessing health care needs and in comparing health care provision (e.g. of surgical intervention rates) to health need. This paper focuses on estimating prevalence of coronary heart disease and uses a Bayesian approach to synthesise information of dif ferent types to make indirect prevalence estimates for geographic units where prevalence data are not otherwise available. One source is information on prevalence risk gradients from national health survey data; such data typ ically provide only regional identifiers (for confidentiality reasons) and so gradients by age, sex, ethnicity, broad region, and socio-economic status may be obtained by regression methods. Often a series of health surveys is available and one may consider pooling strength over surveys by using information on prevalence gradients from earlier surveys (e.g. via a power prior approach). The second source of information is population totals by age, sex, ethnicity, etc from censuses or intercensal population estimates, to which survey based prevalence rates are applied. The other potential data source is information on area mortality, since for heart disease and some other major chronic diseases there is a positive correlation over areas be tween prevalence of disease and mortality from that disease. A case study considers the development of estimates of coronary heart disease prevalence in 354 English areas using (a) data from the Health Surveys for England for 2003 and 1999 (b) population data from the 2001 UK Census, and (c) area mortality data for 2003.