Tackling unhealthy lifestyles can lead to modest improvements in diet, physical activity and smoking behaviours. But in a few studies, trying to change smoking alongside diet or physical activity appeared to be less effective than if these were tackled sequentially.
Many people in the UK have two or more unhealthy habits that significantly increase their risk of the UK’s biggest killers, cancer and heart disease.
Results from this NIHR-funded review of 69 trials (73,873 adults) showed it was possible for people to change these behaviours. Despite this good news, many of the trials had a high risk of bias, and excluded adults who were obese or had type 2 diabetes. This reduces the reliability and application of this research to the whole population, but probably not the strength of the overall advice.
Why was this study needed?
Smoking, having an unhealthy diet, being inactive and drinking too much alcohol significantly increase the risk of developing and dying from cancer and cardiovascular disease.
In the UK, smoking rates have reduced from 20.1% in 2010 to 17.2% in 2015, but that is still around nine million adults, costing the NHS £2 billion per year in treating diseases caused by smoking. In 2015, only 26% of adults ate five or more portions of fruit and vegetables per day. In addition, 26% of adults did less than 30 minutes of physical activity per week.
As many people in the UK have one, two, three or even four of these unhealthy habits, some believe it may be more effective to tackle many at once, rather than individually.
This NIHR-funded review brings all the trial evidence from interventions targeting multiple unhealthy behaviours into one place, in an attempt to summarise the overall effect.
What did this study do?
This systematic review and meta-analysis pooled results from 69 randomised controlled trials including 73,873 adults. Most trials investigated education and skills training to tackle two or more risk behaviours - 72% targeted unhealthy diet and inactivity, 35% diet and smoking and 23% alcohol and smoking.
These multiple risk factor interventions were compared against a minimal intervention, information provision, or active control, such as targeting one behaviour.
Risk of bias was high for more than half of the trials. Follow up was short, typically three to five months, up to a maximum of one to two years. Trials aimed at people with higher risks, e.g. obesity or type 2 diabetes, were excluded, limiting the generalisability of the findings.
What did it find?
Overall, interventions tackling multiple risk behaviours led to modest improvements in diet, physical activity and smoking behaviours:
- Diet: interventions increased fruit and vegetable intake by 0.31 portions, equivalent to about a third of an apple (95% confidence interval [CI] 0.17 to 0.45, 13 trials). People were also 30% more likely to meet fat/meat/dairy intake recommendations (odds ratio [OR] of exceeding recommendations 0.70, 95% CI 0.61 to 0.81, 3 trials).
- Physical activity: people were 27% more likely to meet physical activity recommendations (OR of not meeting recommendations 0.73, 95% CI 0.65 to 0.83, 19 trials).
- Smoking: people were 22% less likely to smoke (OR 0.78, 95% CI 0.68 to 0.90, 17 trials).
- There was insufficient data to determine the best strategy for reducing alcohol intake or risky sexual behaviour.
- Trying to make changes to smoking behaviour was strongly correlated with lower chances of simultaneously improving fruit and vegetable intake (correlation r= ‑0.96), and to a lesser extent, physical activity levels (r=-0.44).
What does current guidance say on this issue?
NICE public health guidance on behaviour change from 2007 (reviewed in 2014) does not specify whether commissioners or providers should use single or multiple risk behaviour targeted interventions simultaneously or in sequence.
Instead, it outlines many best practice behaviour change principles to consider, including;
- ensuring interventions are based on a needs assessment or knowledge of the target audience
- setting out which specific behaviours are to be targeted (for example, increasing levels of physical activity) and why
- prioritising cost-effective interventions or programmes with the best evidence they work.
NICE also have individual guidelines for supporting each lifestyle change.
What are the implications?
The review suggests it would be sensible to consider tackling smoking separately from diet and physical activity, rather than at the same time, for interventions targeting the general-risk adult population.
A situation where this sequencing issue may arise is for adults attending NHS Health Checks who are subsequently enrolled on programmes to help them be healthier in multiple ways.
As stop smoking services are effective and smoking directly causes a quarter of cancer deaths, it may be worth tackling this behaviour first. However, there is likely to be wide variation between individuals in terms of what works best for them, so this review should not discourage people from tackling more than one issue at the same time if they are sufficiently motivated to do so.
Citation and Funding
Meader N, King K, Wright K, et al. Multiple Risk Behavior Interventions: Meta-analyses of RCTs. Am J Prev Med. 2017;53(1):e19-30
This project was funded by the Department of Health Policy Research Programme as part of the Public Health Research Consortium.
ASH. At a Glance Smoking Factsheets. London: Action on Smoking and Health; 2017.
Ebrahim S, Taylor F, Ward K, et al. Multiple risk factor interventions for primary prevention of coronary heart disease. Cochrane Database Syst Rev. 2011;(1):CD001561.
NHS Digital. Statistics on Obesity, Physical Activity and Diet - England, 2017. Leeds: NHS Digital; 2017.
NICE. Behaviour change: general approaches (PH6). London: National Institute for Health and Care Excellence; 2007.
Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre