| Title: | Impact of follow-up time and analytical approaches to account for reverse causality on the association between physical activity and health outcomes in UK Biobank |
| Journal: | International Journal of Epidemiology |
| Published: | 25 Oct 2019 |
| Pubmed: | https://pubmed.ncbi.nlm.nih.gov/31651957/ |
| DOI: | https://doi.org/10.1093/ije/dyz212 |
| URL: | https://academic.oup.com/ije/article-pdf/49/1/162/32995601/dyz212.pdf |
Publication 2623
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Abstract
BACKGROUND: The advent of very large cohort studies (n > 500 000) has given rise to prospective analyses of health outcomes being undertaken after short (<4 years) follow-up periods. However, these studies are potentially at risk of reverse causality bias. We investigated differences in the associations between self-reported physical activity and all-cause and cardiovascular disease (CVD) mortality, and incident CVD, using different follow-up time cut-offs and methods to account for reverse causality bias.</p>
METHODS: Data were from n = 452 933 UK Biobank participants, aged 38-73 years at baseline. Median available follow-up time was 7 years (for all-cause and CVD mortality) and 6.1 years (for incident CVD). We additionally analysed associations at 1-, 2- and 4-year cut-offs after baseline. We fit up to four models: (1) adjusting for prevalent CVD and cancer, (2) excluding prevalent disease, (3) and (4) Model 2 excluding incident cases in the first 12 and 24 months, respectively.</p>
RESULTS: The strength of associations decreased as follow-up time cut-off increased. For all-cause mortality, Model 1 hazard ratios were 0.73 (0.69-0.78) after 1 year and 0.86 (0.84-0.87) after 7 years. Associations were weaker with increasing control for possible reverse causality. After 7-years follow-up, the hazard ratios were 0.86 (0.84-0.87) and 0.88 (0.86-0.90) for Models 1 and 4, respectively. Associations with CVD outcomes followed similar trends.</p>
CONCLUSIONS: As analyses with longer follow-up times and increased control for reverse causality showed weaker associations, there are implications for the decision about when to analyse a cohort study with ongoing data collection, the interpretation of study results and their contribution to meta-analyses.</p>
17 Keywords
- Adult
- Aged
- Cardiovascular Diseases
- Causality
- Cohort Studies
- Exercise
- Female
- Follow-Up Studies
- Humans
- Incidence
- Life Style
- Male
- Middle Aged
- Mortality
- Neoplasms
- Prospective Studies
- Time Factors
6 Authors
- Tessa Strain
- Katrien Wijndaele
- Stephen J Sharp
- Paddy C Dempsey
- Nick Wareham
- Søren Brage
1 Application
| Application ID | Title |
|---|---|
| 20684 | Understanding the associations between environmental exposures, health behaviours and health outcomes |
Enabling scientific discoveries that improve human health