Back in Spring 2024, on my way to my local leisure centre, I came across a newly installed container, yellow and boldly displaying, “Let’s prevent disease together”. A couple of weeks later, I got an invitation in the mail to participate in the research programme, “Our Future Health” by filling out an online health questionnaire and booking a short clinic appointment (to the aforementioned bright container, which turned out to be a mobile clinic). Whist I was immediately interested in the prospect, I was met with mixed reactions from friends and family: mild surprise, slight wariness and a recurrent question: “what is in it for me?”. As Our Future Health, a programme aiming to transform the prevention, detection and treatment of conditions like dementia and cancer, has now over a million participants across the UK (UK Research and Innovation, 2024), I would like to explore the impact of large-scale cohort studies, whether the promise of, “Research that benefits everyone” is met and what drives individuals to partake in these projects.
Population-based cohort studies are a specific category of epidemiology studies in which a defined population is followed up and observed longitudinally to assess exposure and outcome relationships (Szklo, 1998). The UK has a long history of population cohort studies including the 1946 Birth Cohort (Pearson, 2011), the world’s longest continuously running birth cohort, UK Biobank (Collins, 2012) , which tracks half a million participants, and the Million Women Study (Oxford Population Health, n.d.), the largest longitudinal study of women’s health. They represent a major long-term commitment for participant, researchers and funders, but their strength is in their ability to identify multiple risk factors over time. This is particularly relevant to assess exposures that cannot be randomised, such as smoking and social circumstances, or in identifying the effect of one risk factor on multiple outcomes (Pell et al., 2014). Population cohort studies are key in providing longitudinal data on the impact of determinants of health, disease and disabilities and are a robust design explore causality (Szklo, 1998). For example, the effects of occupational, environmental and psychosocial factors on diseases such as cancer, or determinants of quality of life, such as suffering from chronic diseases or environmental factors (such as pollution). In addition, the large cohort allows for nested studies in subpopulations that still have, even in case of small effects, enough power to investigate how the interaction between health behaviour, environmental, and societal factors have an impact on health outcomes. Cohort studies have contributed to great advances in health, in cardiovascular diseases for instance (Paneth & Monk, 2018).
While population-based cohort studies have become the cornerstone of genetic epidemiology, the participants are rarely presentation of the general population. In the UK Biobank project, out of the 9,238,453 men and women invited to join, 503,317 (5.45%) consented and were recruited between 2006 and 2010. Overall, the participation rate was higher in older age groups (9% in those aged ≥60 years and 3% in those aged 40–44 years), and in less socioeconomically deprived areas (8.3% among persons from the least deprived areas and 3.1% among persons from the most deprived areas). In addition, 94.6% of participants were of White ethnicity (Fry et al., 2017). This is echoing data from the National Institute for Health and Care Research (NIHR) revealing that UK geographies with the highest burden of disease also have the lowest number of patients taking part in research (Darko, 2023).
How to improve diversity in research in a systemic way is a fascinating and crucial topic, worth of another long format piece in its own right. It is not our focus today, so I will merely signpost interested readers to the NHS good practice guide to Increasing Diversity in Research Participation and to Boden-Albala’s publication Confronting legacies of underrepresentation in clinical trials: The case for greater diversity in research (Boden-Albala, 2022). Let’s go back to ‘Our Future Health’ and my motivation to participate as young woman of Black African heritage. Without putting the responsibility back on individuals or communities to change the tide of long-standing inequalities, I am acutely aware, through my work, of how instrumental representation can be to produce generalisable and sound research. “You have to be in it to win it”, so I view this as a gift to my community and future generations, a way (arguably infinitesimal) to move the dial and the promise of more health equity in prevention, diagnostic and health treatment in years to come.