title: An evaluation of UK secondary data sources for  the study of childhood obesity, physical activity  and diet.
abstract: BACKGROUND
  This study assesses the potential of secondary datasets for measuring recent and future trends in childhood obesity, physical activity and diet in the UK, at national, regional and sub-regional levels, and in relation to inequalities.
  
  
  METHODS
  Relevant datasets were identified using online searches; they were excluded if they had low sample sizes, were assembled prior to 1990 or on only one occasion, were not potentially accessible, or were limited to a specific population. Remaining datasets were assessed according to content, sampling frame and size, timing and ability to be used to assess inequalities and regional trends.
  
  
  RESULTS
  A total of 96 datasets were identified, but only 11 had the potential to be used to assess trends. Eight of these contained data on physical activity, 8 on diet and 3 on obesity. The period over which trends might be assessed varied from 2 years to over 10, with over half of the datasets expected to continue data collection into the future. Most had the potential to be used to assess inequalities and also regional and sub-regional level trends, albeit with relatively small sample sizes. There were some limitations to the datasets, such as non-objective measures of diet and physical activity and, in some, low response rates, which would require further consideration when utilizing individual datasets.
  
  
  CONCLUSIONS
  Awareness of the potential of secondary datasets for monitoring trends in childhood obesity should be raised, alongside the financial and intellectual capacity to enhance and exploit them.
authors.affiliation: Centre for Paediatric Epidemiology and Biostatistics, UCL Institute of Child Health, University College London, London, UK. a.pearce@ich.ucl.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Pearce
authors.forename: R
authors.initials: R
authors.lastname: Jenkins
authors.forename: C
authors.initials: C
authors.lastname: Kirk
authors.forename: C
authors.initials: C
authors.lastname: Law
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004032:Diet / Q000639:trends*; D015444:Exercise / Q000502:physiology*; D006306:Health Surveys; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009765:Obesity / Q000453:epidemiology*; D006113:United Kingdom / Q000453:epidemiology