25.05.2020

Lifestyle Risk Factors, Inflammatory Mechanisms, and COVID-19 Hospitalization: A Community-Based Cohort Study of 387,109 Adults in UK

Epidemiological Transversal
Hamer M et al
Brain Behav Immun

Main result

  • - Analysis of a sample of 387,109 people (56.2 ±8.0 years, 55.1% female, 94.5% British Caucasian) living on 5 March 2020.
  • - 33.5% with excessive alcohol consumption, 23.5% obese, 9.7% smokers, 17.8% physically inactive, 4.9% diabetics, 56.1% hypertensive, 5.2% cardiovascular diseases.
  • - 760 people (about 0.2%) hospitalized and COVID-19 positive.
  • - Dose-response relationship between risk factor score (cf. Methods) and risk of hospitalisation COVID-19, a score of 8 (worst score) corresponding to an RR of 4.41. This association was little modified by the adjustment on the covariates.
  • - The RRs for each lifestyle risk factor after adjustment for age, sex and other lifestyle risk factors are: 1.32 for physical activity, 1.42 for smoking, 2.05 for obesity. No significant association for excessive alcohol consumption (1.12; 0.93, 1.35).
  • - Population attributable fraction for the combination of smoking, physical inactivity and BMI>25 was 51.4%.
  • - Subgroup analysis (n=363,263) on high-sensitivity CRPhs: association between lifestyle risk factor score and CRPhs after adjustment for age, sex, education, ethnicity, diabetes, EHV and cardiovascular disease (B= 0.10, 95% CI, 0.09, 0.11). Dose-response relationship between CRPhs and hospitalisation COVID-19. Mitigation between 10 and 16% of the association between lifestyle risk factor score and COVID-19 hospitalization after adjustment for CRPhs suggesting possible mediation.

Takeaways

- The RRs for each lifestyle risk factor after adjustment are: 1.32 for physical activity, 1.42 for smoking, 2.05 for obesity. No significant association for excessive alcohol consumption.

- Dose-response relationship between lifestyle risk factor score and risk of hospitalization COVID-19, up to x 4.41.

- A low-level inflammatory syndrome associated with risky lifestyles may mediate this observed risk.

- Population attributable fraction for the combination of smoking, physical inactivity and BMI>25 of 51.4%.

Strength of evidence Weak

- prospective cohort study
- relatively few cases
- the period of interest is short and far removed from the last risk factor assessment (> 10 years); and
- classification bias very likely because the event taken into account is a hospitalisation with a positive SARS-CoV-2 test (the tests being reserved for this period for hospitalised persons with symptoms compatible with COVID-19) and not persons with a diagnosis of severe COVID-19 requiring hospitalisation in the strict sense of the term.
- subgroup analysis appearing to be performed retrospectively (not detailed in the methods).
- pre-proof

Objectives

Assess the association between lifestyle risk factors (smoking, alcohol consumption, physical inactivity, overweight) and risk of hospitalization for COVID-19 infection.

Method

- Prospective cohort study based on the UK Biobank cohort.

- Initial collection of data on smoking, alcohol consumption and physical activity levels by questionnaire and measured BMI over the period 2006-2010.

- Collection of cases of COVID-19 hospitalized in England for the period from 16 March to 26 April 2020.

- Weighting for risk factors: smoking (0=never, 1=severe, 2=active), physical activity (0=compliant with recommendations, 1=active but below recommendations, 2=inactive), alcohol consumption (0=abstinent or very occasional consumption, 1=moderate consumption not exceeding recommendations, 2=heavy consumption exceeding recommendations), BMI (0=BMI<25, 1=overweight, 2=obesity). Highest score 0, Lowest score 8.

- Calculation of RR with 95% CI and adjustment for age, sex, then education, ethnicity, diabetes, hypertension and cardiovascular disease.

- Calculation of the population attributable fraction (PAF) based on the prevalence study of the Health Survey for England.

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