1 / 19

Longitudinal analysis of diet in ALSPAC

Longitudinal analysis of diet in ALSPAC. Laura D Howe EUCCONET, Bristol, October 2011. Outline. Trajectories of energy intake and macro-nutrients Planned analysis Very preliminary results. Data issues. Different # measures per individual Exact ages of measurement vary

shawn
Download Presentation

Longitudinal analysis of diet in ALSPAC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Longitudinal analysis of diet in ALSPAC Laura D Howe EUCCONET, Bristol, October 2011

  2. Outline • Trajectories of energy intake and macro-nutrients • Planned analysis • Very preliminary results

  3. Data issues • Different # measures per individual • Exact ages of measurement vary • FFQ and diary data • Want a full trajectory that is comparable for all individuals • Want to reduce the dimensionality of the data

  4. Multi-level models:Random-slopes model yij= a + u0i + (b+u1i)tij+ eij yij=weight for individual i at occasion j, time tij • Effect of time varies between individuals (u1i) • The model estimates: • The regression coefficients a and b • Individuals intercepts (a + u0i) • Individual slopes (b+u1i) • The covariance between the intercept and slope

  5. Multi-level models in pictures! kCal Average regression line Age

  6. Multi-level models in pictures! kCal Age

  7. But the real world isn’t always linear... • Model the data as a curve? • Model the data as piecewise linear?

  8. What shape?

  9. What shape?

  10. Raw data

  11. Next steps • Include adjustment for over-reporting • Repeat for fat, protein, carbs, unhealthy sugars • Repeat for energy-adjusted fat, protein, carbs, unhealthy sugars

  12. Using the models: diet as the exposure • Individual-level residuals = how an individual deviates from the normal • Use in standard regression techniques • Obesity • NAFLD • Cardiovascular risk factors • etc

  13. Using the models: diet as the outcome • Include the exposure in the multilevel models • e.g. SEP • For each category of SEP, allow: • Different intercept • Different slope in each period

  14. Acknowledgements • Emma Anderson • Kate Tilling • Debbie Lawlor • ALSPAC nutrition team

More Related