Use of the census samples of anonymised records (SARs) and survey data in combination to obtain estimates at local authority level

Estimating BMI distributions by age and sex for local authorities in England: a small area estimation study

OBJECTIVES

Rates of overweight and obesity vary across England, but local rates have not been estimated for over 10 years. We aimed to produce new small area estimates of body mass index (BMI) by age and sex for each lower tier and unitary local authority in England, to provide up-to-date and more detailed estimates for the use of policy-makers and academics working in non-communicable disease risk and health inequalities.

DESIGN

We used generalised linear modelling to estimate the relationship between BMI with social/demographic markers in a cross-sectional survey, then used this model to impute a BMI for each adult in locally-representative populations. These groups were then disaggregated by 5-year age group, sex and local authority group.

SETTING

The Health Survey for England 2018 (cross-sectional BMI data for England) and Census microdata 2011 (locally representative).

PARTICIPANTS

A total of 6174 complete cases aged 16 and over were included.

OUTCOME MEASURES

Modelled group-level BMI as mean and SD of log-BMI. Extensive internal validation was performed, against the original data and external validation against the National Diet and Nutrition Survey and Active Lives Survey and previous small area estimates.

RESULTS

In 94% of age-sex are groups, mean BMI was in the overweight or obese ranges. Older and more deprived areas had the highest overweight and obesity rates, which were particularly in coastal areas, the West Midlands, Yorkshire and the Humber. Validation showed close concordance with previous estimates by local area and demographic groups.

CONCLUSION

This work updated previous estimates of the distribution of BMI in England and contributes considerable additional detail to our understanding of the local epidemiology of overweight and obesity. Raised BMI now affects the vast majority of demographic groups by age, sex and area in England, regardless of geography or deprivation.

Fat nation: deciphering the distinctive geographies of obesity in England

Much attention is focused on obesity by both the media and by public health. As a health risk, obesity is recognised as a contributing factor to numerous health problems. Recent evidence points to a growth in levels of obesity in many countries and particular attention is usually given to rising levels of obesity among younger people. England is no exception to these generalisations with recent studies revealing a clear geography to what has been termed an 'obesity epidemic.' This paper examines the complexities inherent in the geography of adult obesity in England. Existing knowledge about the sub-national geography of obesity is examined and assessed. Multilevel synthetic estimation is then used to construct an age-sex-ethnicity disaggregated geography of obesity. These differing geographies are compared and contrasted with pre-existing findings and explored at multiple scales. A complex picture of the geography of obesity in England is revealed.

Predicting small area health-related behaviour: a comparison of multilevel synthetic estimation and local survey data

A recent paper in Social Science and Medicine (Twigg et al. 50 (2000) 1109) outlined an approach to the estimation of prevalences of small-area health-related behaviour using multilevel models. This paper compares results from the application of the multilevel approach with those derived using the more traditional strategy of the local 'lifestyle' survey. Estimations of smoking prevalence and high alcohol consumption are examined and critical assessments made of both estimation approaches. It is concluded that the alternative method is more suited towards the prediction of smoking rates as opposed to unsafe alcohol consumption.

The value of the SARs in spatial and area-level research

"The papers in this issue exemplify in various ways the value of the Samples of Anonymised Records (SARs) for Britain and Northern Ireland to spatial and area-level research. Before highlighting some of the strengths of the SARs for this type of analysis we give a brief overview of the structure and content of the SARs."