About a quarter of UK adults have two or more chronic conditions. This multimorbidity, as it’s known, is concentrated in lower socioeconomic groups, is projected to increase over the next 15 years, and becomes more common with age. Around two thirds of over-65s have two or more chronic conditions.
We investigated whether biomarkers – measures taken in routine blood tests, related to stress and ageing – could be used to predict future health and health-related quality of life 3-5 years later. If so, they could provide the impetus for earlier intervention or changes in lifestyle to allow for healthier ageing.
The data
Waves 2 and 3 of Understanding Society provided blood samples and other data from over 7,700 people. Biomarkers in the samples were used to create an allostatic load ‘score’ that is, a measure of risk for ill health.
We combined this with self-rated health scores from Waves 1-7 of the Study to examine the relationships between allostatic load and self-reported physical and mental health, and overall health-related quality of life. We took into account factors such as age, income, education, employment, ethnicity smoking, alcohol consumption, exercise, diet, and personality type when examining the relationship.
Findings
With our co-authors, Stephen O’Neill and Liam Heaney, we found that allostatic load, measured between 2010 and 2013, predicted self-rated health up to five years later. People with a higher allostatic load at baseline reported a decrease in their physical health and health-related quality of life later on.
This is in line with the findings of those who developed the concept of allostatic load, who found that allostatic load predicted lower physical functioning 7.5 years after the baseline measurement. It is also consistent with studies that have found allostatic load to predict risk of disease, premature death and use of healthcare.
Implications
What we found has implications for health promotion and education. Although there are social, economic, political and cultural factors which influence people’s use of healthcare, behavioural factors are important, too. Some diseases do not have obvious symptoms which can delay people seeking help. Information on allostatic load based on simple blood tests could be the catalyst for a change in lifestyle or other interventions that delay premature ageing and lower mortality risk.
The use of such measures by GPs could provide a teachable moment to encourage lifestyle changes or otherwise intervene to improve future health.
Other causes of stress
There are socioeconomic differences in allostatic load which are largely beyond the control of the individual, and which they cannot tackle with lifestyle changes. Increases in income inequality appear to play a causal role in poorer health outcomes, and stress may be part of that. Tackling these broader social determinants lies beyond the health service and requires coordinated action across government departments. As noted in the Wanless Report almost 20 years ago though it requires action by us all.
The need for more data
Our findings come with some caveats. We cannot definitively say that the effects we’ve seen are causal, because we can’t rule out unobserved factors – and there are other measures of allostatic load and self-rated health. Future research may find new aspects of the relationship between the two – and the choice of which biomarkers to measure (and how to measure them) is itself an area of research.
More frequent measurement of allostatic load over a longer time frame would also provide more insights into the predictive values of biomarkers on future health and well-being.
Our conclusions
We have shown that allostatic load predicts self-rated physical health and health-related quality of life.
The insights we’ve gained could be useful for both clinical practice and policy. In particular, policies which target the young and those who experience socio-economic disadvantage could help healthier ageing and reduce health inequalities.
Authors
Luke Barry
Luke Barry is a Research Fellow at the School of Medicine, Dentistry and Biomedical Sciences at Queens University Belfast
Ciaran O'Neill
Ciaran O'Neill is a Professor in the School of Medicine, Dentistry and Biomedical Sciences at Queens University Belfast
