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Abstract
Objectives To explore age trajectories of body mass index (BMI) and waist circumference (WC) and to examine whether these trajectories varied by wealth.
Design Nationally representative prospective cohort study.
Setting Observational study of people living in England.
Participants 7416 participants aged 52 and over of the English Longitudinal Study of Ageing (2004–2012).
Primary outcome measures BMI and WC assessed objectively by a trained nurse.
Main exposure measure Total non-pension household wealth quintiles defined as financial wealth, physical wealth (such as business wealth, land or jewels) and housing wealth (primary and secondary residential housing wealth), minus debts.
Results Using latent growth curve models, we showed that BMI increased by 0.03 kg/m2 (95% CI 0.02 to 0.04, p<0.001) per year and WC by 0.18 cm (95% CI 0.15 to 0.22, p<0.001). Age (linear and quadratic) showed a negative association with BMI and WC baseline and rates of change, indicating that older individuals had smaller body sizes and that the positive rates of change flattened to eventually become negative. The decline occurred around the age of 71 years for BMI and 80 years for WC. Poorest wealth was significantly related to higher baseline levels of BMI (1.97 kg/m2 95% CI 0.99 to 1.55, p<0.001) and WC (4.66 cm 95% CI 3.68 to 2.40, p<0.001). However, no significant difference was found in the rate of change of BMI and WC by wealth, meaning that the age trajectories of BMI and WC were parallel across wealth categories and that the socioeconomic gap did not close at older ages.
Conclusions Older English adults showed an increase in BMI and WC over time but this trend reversed at older old age to display a sharp decrease. At any given age wealthier people had more favourable BMI and WC profile.
- body mass index
- waist circumference
- trajectories
- wealth
- ageing
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Footnotes
Contributors PZ designed and conducted the study. PZ and CL analysed the data and wrote the manuscript.
Funding This work was supported by the National Institute of Aging (R01AG017644) and a consortium of UK government departments coordinated by the Economic and Social Research Council.
Disclaimer The funding bodies had no role in the study design; in the collection, analysis and interpretation of data; in the writing of the manuscript; and in the decision to submit the manuscript for publication.
Competing interests None declared.
Ethics approval ELSA was approved by NHS Research Ethics Committees under the National Research and Ethics Service.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement ELSA data are available free on registration to the UK Data Archive http://data-archive.ac.uk/, codes are available directly from the authors.
Patient consent for publication Not required.