Oral Presentation Australian & New Zealand Obesity Society 2014 Annual Scientific Meeting

Contributions of local-area fast-food availability and area-based weight and dietary norms to 10-year change in cardiometabolic risk (#88)

Suzanne J Carroll 1 , Catherine Paquet 1 2 , Natasha J Howard 1 , Neil T Coffee 1 , Robert Adams 3 , Anne W Taylor 3 , Theo Niyonsenga 1 , Mark Daniel 1 4 5
  1. Spatial Epidemiology and Evaluation Research Group, School of Population Health and Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia
  2. Research Centre of the Douglas Mental Health University Institute, Verdun, Quebec, Canada
  3. Discipline of Medicine, The University of Adelaide, Adelaide, SA, Australia
  4. Department of Medicine, The University of Melbourne, Melbourne, Victoria, Australia
  5. South Australian Health & Medical Research Institute, Adelaide, South Australia, Australia

Background: Efforts to reduce cardiometabolic disease often target individual-level risk factors. However, individual dietary behaviour and body mass index (BMI) may be influenced by the geographic patterning of food sources and local-area norms. Norms figure prominently in socio-behavioural theories yet spatial variations in norms have rarely been investigated in predicting individual health outcomes.  This study assessed the contributions of fast-food availability and local-area norms for dietary behaviour and BMI to 10-year change in cardiometabolic risk.

Methods: Cardiometabolic risk, expressed using a validated continuous clinical index, was calculated using data from a population-based biomedical cohort in Adelaide, South Australia over three waves of follow up, 2000-2010.  Local-area exposures were defined for participants (n=2228) using 1600m road-network buffers.  Local-area norms (proportion residents with BMI ≥25 kg/m2 or not meeting fruit intake of ≥2 serves/day) were aggregated from individual-level self-reported data from a state-wide surveillance system, pooled across 2006-2010 for the study area.  Fast-food availability (count of outlets) was extracted from a retail database.  Separate multilevel models each featuring one local-area norm with fast-food availability as predictors of 10-year change in cardiometabolic risk were adjusted for area-level socioeconomic status and individual-level covariates.

Results: In separate models including fast-food availability, greater local-area proportion of residents with BMI ≥25 kg/m2 or not meeting fruit intake of ≥2 serves/day predicted worsening cardiometabolic risk across 10-years of follow up.  Fast-food availability was not related to cardiometabolic risk. There was no evidence of interaction effects between local-area exposures.

Conclusions: Local-area norms (prevalence of unhealthful BMI and fruit consumption) reflect compositional population characteristics.  Fast-food availability reflects built environmental context.  In this study, only compositional norms, not fast-food context, predicted 10-year worsening of cardiometabolic risk.  The implication of this longitudinal investigation is that the targeting of compositional norms might be more important than the targeting of fast-food context.