EPIC-Norfolk: Summary Findings

 

Napping and all-cause mortality risk

In recent years, there has been growing evidence of a relationship between habitual sleep and mortality. The majority of these studies focussed on night-time sleep duration, leaving the implications of daytime napping poorly understood. We therefore investigated the associations between daytime napping and all-cause or cause-specific mortality within our EPIC population.

Daytime napping was associated with an increased risk of all-cause mortality, independent of age, sex, social class, education level, marital status, employment status, body mass index, physical activity level, smoking status, alcohol intake, depression, self-reported general health, use of hypnotic drugs or other medications, time spent in bed at night and presence of pre-existing health conditions. This association was more pronounced for death from respiratory diseases and in individuals aged 65 years or younger.

Excessive daytime napping may therefore prove to be a useful indicator of an underlying health risk, especially in respiratory conditions and amongst those 65 years old or younger. Further research is required, however, to clarify the nature of this observed association.

Leng et al. Daytime napping and the risk of all-cause and cause-specific mortality: a 13-year follow-up of a British population. Am J Epidemiol. 2014 May 1; 179(9): 1115-24.

 

Self-reported sleep patterns in a British population cohort

Sleep patterns have been linked to various health outcomes, but sleep patterns representative of a British population have not been extensively reported. We therefore aimed to describe the sleep characteristics recorded by our Norfolk-based participants, with a particular emphasis on measures of sleep quality.

On average, the reported time in bed (TIB) was more than 1.5h longer than sleep duration. Compared to men, women spent 15 minutes longer in bed, but slept for 11 minutes less and reported more sleep difficulties. Sleep duration and TIB varied with socioeconomic factors, but sleep proportion (the ratio of sleep duration to TIB) was consistently lower among women, nonworkers, and older individuals, as well as those who were widowed, separated, or divorced; those who reported sleep difficulties and more frequently used sleeping medication; and those who had lower education, poorer general health, or a major depressive disorder.

Whilst self-reported sleep duration and TIB may therefore have different meanings and implications for health, sleep proportion was shown to be the most useful indicator when describing sleep patterns within a general population.

Leng et al. Self-reported sleep patterns in a British population cohort. Sleep Med. 2014 Mar;(3): 295-302.

 

People with low vision (LV) are more likely to live in the most deprived areas

Previous studies have shown poor vision to be associated with lower socioeconomic status, but less is known about its relationship to area deprivation. Though the individual links between area deprivation and access to optometric services, access with low vision, and area deprivation and low vision are well established, ours is the first study to link all three into one analysis.

LV was found to be strongly associated with deprivation; people with LV being nearly twice as likely to live in the most deprived areas compared to those with good vision. Those who were older, women, had lower levels of education and had undergone previous cataract operations were more likely to have LV; with those aged >65 years being over three times more likely to have LV than younger people. The association between LV and area deprivation was found to be independent of socioeconomic status, but encouragingly partly mediated by uncorrected refractive error ((URE) nearsightedness, farsightedness, astigmatism and presbyopia).

This finding is important as it has the potential to influence future policy, as by targeting and treating URE within deprived areas – either with corrective glasses, contact lenses or through refractive surgery – we may be able to reduce the health inequalities evident and associated with LV.

YIP JLY, et al. Area deprivation, individual socioeconomic status and low vision in the EPIC-Norfolk Eye Study. J Epidemiol Community Health. 2014 Mar; 68(3): 204-10.

 

Self-reported vision (SRV), visual acuity (VA) and the risk of falling

Whilst previously published studies present strong evidence that visual impairment (VI) is a risk factor for falls, detecting visual impairment by objective measures and managing it with optometric and ophthalmic referrals does not appear to reduce falls. It is therefore possible that visual acuity (VA) measures (the standard reading from the increasingly difficult Snellen chart) may detect VI but not those people at increased risk of falling due to their visual problems. Encompassing a variety of objective visual function measures and not solely VA, self-reported vision (SRV) has been suggested a possible reliable alternative. We investigated the relationship between VA and SRV, and their comparative association to falls within the EPIC population.

8317 participants were analysed with 26.7% reporting having had a fall within the last 12 months. Self-reporting vision as poor (describing one’s vision as fair or poor in relation to distance) was associated with a 32% increase in fall risk. This association was independent of the VA score, with the association between a poor VA (poor reading from the Snellen chart) and likelihood of falling no longer being found to be statistically significant after accounting for SRV.

This finding supports the notion that simply correcting VA is not enough to reduce a person’s fall risk and that SRV (the individual’s own perception of their vision) could be used as a simple proxy measure for other aspects of visual function to detect those people requiring vision-related fall interventions.

YIP JLY, et al. Visual acuity, self-reported vision and falls in the EPIC-Norfolk Eye study. Br J Opthalmol. 2014 Mar; 98(3): 377-82.

 

The physical capability of community-based men and women

We aimed to explore the physical capability of men and women within our cohort, with a view of measuring the estimated scale of the population who would be eligible for muscle mass measurement if adhering to criteria for diagnosing sarcopenia (the loss of skeletal muscle mass and functional strength as a result of ageing) suggested by The European Working Group for Sarcopenia in Older People’s (EWGSOP).

Approximately 1 in 4 older participants (>65 years) fulfilled criteria for muscle mass measurement, with a greater proportion of women rather than men falling below threshold criteria (33.6% vs 23.6%). With regards to physical capability, women were 12.4 kg weaker (grip strength wise) than men, took 12% longer to perform five chair stands and were 1.82 times more likely to be unable to hold a tandem stand (one foot placed directly in front of the other) for 10 seconds, although walking speed across the genders was similar. Physical capability was inversely associated with age and per year: walking speed decreased by 0.01 m/s and grip strength decreased 0.49 kg in men and 0.25kg in women. Despite this, it is important to mention, however, that there was still variation within age-groups and that not all older people had low physical capability. In fact some older participants outperformed their younger counterparts. Every effort should therefore be made to optimise functional health in later life since poor function is not inevitable.

Keevil et al. The physical capability of community-based men and women from a British cohort: the European Prospective Investigation into Cancer (EPIC)-Norfolk study. BMC Geriatrics 2013, 13:93.

 

The effects of retirement upon physical activity

Physical activity is important for maintaining health, mobility and well-being in older age. Despite the well-established benefits, global physical activity surveillance data shows that adults over the age of 60 years are the least active segment of the adult population. Retirement is associated with an increase in recreational physical activity but its impact on other domains of activity (at home, for transport and travel) and sedentary behaviour (time spent sitting or lying down, such as watching television (TV)) remains largely unknown. We therefore examined the association between retirement and changes in domain-specific physical activity, thus overall physical activity and TV viewing.

We found that whilst retirement was associated with a decline in overall activity, physical activity did increase with retirement in respects to recreational (exercise, sports, walking and cycling for pleasure, DIY and gardening) and household pursuits (household chores and caregiving). We observed a significant interaction between retirement and social class in respects to both overall and domain-specific physical activity, with the exception of household activity, as well as a notable difference in how the both genders expend physical energy. Furthermore, retirement was associated with a mean increase in TV viewing time, with the largest increase being among those who previously worked within the manual professions.

Barnett, I., van Sluijs, E., Ogilvie, D., Wareham, NJ. (2013) Changes in household, transport and recreational physical activity and television viewing time across the transition to retirement: longituindal evidence from the EPIC-Norfolk cohort. Journal of epidemiology and community health 68: 8, 747-53.

 

Can physical activity reduce the risk of glaucoma?

It is our aim to further understand the factors that increase risk or help to protect people from common eye diseases within the UK. In the third health check, we included a comprehensive eye examination, which, along with the other data we have collected, will allow us to investigate the importance of diet, lifestyle and environment on eye disease. Glaucoma is one of the leading causes of blindness in the UK and low ocular perfusion pressure (OPP) is a known risk factor. We have recently reported on the effect of physical activity and OPP; this is the first time, to our knowledge, that this relationship has been explored. Although further investigations are required, these early results show that people with a previous active lifestyle have a lower risk of having low OPP. In summary, increased physical activity may have some benefits and could potentially modify glaucoma risk.

Jennifer L.Y. Yip, David C. Broadway, Robert Luben, David F. Garway-Heath, Shabina Hayat, Nichola Dalzell, Pak Sang Lee, Amit Bhaniani, Nicholas J. Wareham, Kay-Tee Khaw and Paul J. Foster. Invest. Ophthalmol. Vis. Sci. October 17, 2011 vol. 52 no. 11 8186-8192

 

Too much television viewing increases risk of death by heart disease

Heart disease is responsible for a third of the deaths in the UK. At EPIC, we found that each hour in front of the television per day multiplied the risk of death from heart disease by a factor of 7%, even after taking into account other well-known risk factors, such as lack of exercise, smoking, obesity and poor diet. In this study, 373 of the 13,197 Norfolk participants died from heart disease, and the amount of time spent watching television was a significant marker of likelihood of death from heart disease. It was estimated that 8% of these deaths (30 people) might have been avoided if TV viewing times had been reduced from the UK average of four hours a day to just one hour.

The main message here was that our bodies are not designed to sit for long periods, and by watching a couple of hours less TV a night and being physically active for at least 30 minutes a day can substantially reduce our risk of heart disease. Furthermore, this study showed that the number of hours spent in front of the TV could be included in a future assessment of overall risk of heart disease.

Katrien Wijndaele, Soren Brage, Herve Besson, Kay-Tee Khaw, Stephen J Sharp, Robert Luben, Nicholas J Wareham, Ulf Ekelund. (2011) Television viewing time independently predicts all-cause and cardiovascular mortality: the EPIC Norfolk Study. Int J Epidemiol Feb 40 (1):150-159

 

Dealing with negative emotions reduces risk of heart disease

We examined the relationship between mastery, which is defined as the ability to control negative emotions (and not perceiving stressful experiences as beyond personal control), and cardiovascular disease (CVD). We found in this study of 19,067 men and women, with no previous heart disease or stroke at baseline, that those individuals who perceived that they had limited control over their life circumstances had an increased risk of CVD mortality, and it was suggested that this personal characteristic of mastery should be given more attention in further studies.

Paul G Surtees, Nicholas W J Wainwright, Robert Luben, Nicholas J Wareham, Sheila A Bingham, Kay-Tee Khaw. (2010) Mastery is associated with cardiovascular disease mortality in men and women at apparently low risk. Health Psychol Jul 29 (4):412-420

 

Health inequalities across the social classes

Although the health of the total population in the UK is improving, health inequalities exist, with the gap now widening between the rich and poor. The causes of health inequalities are complex and include nutrition, lifestyle factors, age, occupation, socio-economic factors, as well as access to healthcare. In EPIC, we demonstrated that lower social class is a risk factor for stroke incidence in both men and women, even after accounting for the other lifestyle and psychosocial factors that are classically associated with this condition. This finding is important for the reduction of inequalities in health, as we need to further understand the associations and implications of social class.

Emily McFadden, Robert Luben, Nicholas Wareham, Sheila Bingham, Kay-Tee Khaw. (2009) Social class, risk factors, and stroke incidence in men and women: a prospective study in the European prospective investigation into cancer in Norfolk cohort. Stroke Apr 40 (4):1070-1077

 

Healthy living 'can add 14 years'

With so much information available nowadays on healthy lifestyles, it can seem confusing to the average person as to what is beneficial to our health, and in turn, this makes it difficult for health professionals to encourage people to make changes to their habits. In EPIC-Norfolk, we demonstrated the combined impact of four healthy behaviours: not smoking, exercising, eating fruits and vegetables, and drinking alcohol moderately, relating this to normal every day activities. People were counted as exercising if they did as little as an hour a week. And those with a certain level of vitamin C in their blood were considered to be eating enough fruit and vegetables. People who drank between one to fourteen units of alcohol a week (around nine 125 ml glasses of wine, or seven pints of 3-4% beer) were considered "moderate" drinkers as opposed to drinking none, or more.

Our results clearly showed that people who drink moderately, exercise, quit smoking and eat five servings of fruit and vegetables each day live on average 14 years longer than people who adopt none of these behaviours. This result demonstrates that modest and achievable lifestyle changes can have a marked effect on health.

Khaw et al., Combined Impact of Health Behaviours and Mortality in Men and Women: The EPIC-Norfolk Prospective Population Study . PLoS Medicine5 (1) e12. dol:10.1371/journal.pmed.0050012 Published January 8 2008

 

Coping well with stress can cut the risk of a stroke

We examined the relationship between sense of coherence, an indicator of a person's ability to adapt to social stress, and subsequent stroke risk. Participants with a strong sense of coherence, who reported that they took less time to adapt to life events, had a 24 per cent lower risk of stroke over a 7 year follow-up independent of other factors. Sense of coherence is a measure of how strongly a person believes that what happens in their life is comprehensible, manageable and meaningful. These results show that those people who have the ability to cope with stress can reduce their risk of having a stroke by around a quarter.

Paul G. Surtees, Nicholas W.J. Wainwright, Robert L. Luben, Nicholas J. Wareham, Sheila A. Bingham, and Kay-Tee Khaw Adaptation to social adversity is associated with stroke incidence: evidence from the EPIC-Norfolk prospective cohort study Stroke 2007: 38: 1447 - 1453 

 

Eating breakfast is good for you

Eating breakfast is on the decline. We investigated the association between percentage of total daily energy intake consumed at breakfast and weight change over the follow-up period in our cohort and found that although all participants gained weight during the course of the study, those who consumed 22 to 50% of their energy at breakfast had the lowest BMI compared to people who consumed only 0 to 10% of their energy at breakfast and a 1% increase in the proportion of total energy consumed at breakfast time was associated with 21g less weight gain. These findings indicate consuming a higher proportion of total daily calories at breakfast is associated with relatively lower weight gain in middle age.

Purslow LR, Sandhu MS, Forouhi N, et al. Energy Intake at Breakfast and Weight Change: Prospective Study of 6,764 Middle-aged Men and Women. Am J Epidemiol 2007; Dec 12

 

Physical activity and increased longevity


While physical activity has been associated with improving health, including reducing risk of heart disease and stroke, it is not clear how much physical activity is needed for health benefits.  Many studies have only looked at leisure time physical activity but not taken into account work based activity.  In EPIC-Norfolk we developed a simple pragmatic index of physical activity, suitable for use in general practice, which combines both work and leisure time physical activity.  Men and women who were moderately active or active had about one third lower risk of death from any causes or of having heart disease or strokes over the next eight years compared to men and women who were inactive. Compared to being inactive, (sedentary work, no leisure time physical activity), even those who were moderately inactive, (sedentary work with up to half and hour physical activity such as cycling, swimming, keep fit etc., or standing work such as hairdresser, guard, shop assistant without leisure time activity), had about 20% lower risk of death and cardiovascular disease.  Not being completely inactive compared to being inactive was comparable to being about three years younger in terms of longevity. Even relatively small and relatively achievable differences in physical activity are associated with big differences in health. 

Khaw KT et al.  Work and leisure time physical activity assessed using a simple, pragmatic validated questionnaire and incident cardiovascular disease and all cause mortality in men and women:  The European Prospective Investigation into Cancer in Norfolk prospective population study.  Int J Epidemiology 2006; Aug;35(4):1034-43.

 

Obesity and cancer risk

Obesity appears to be a risk factor for a number of cancers including breast cancer in women after the menopause, and kidney cancer. Avoiding obesity may be one way to reduce risk of a number of cancers. Identifying why obesity may increase cancer risk may help us understand how better to prevent or treat cancer.

Lahmann PH, et al. Body size and breast cancer risk: findings from the European Prospective Investigation into Cancer And Nutrition (EPIC). Int J Cancer 2004;111:762-71.

Pischon T et al. Body size and risk of renal cell carcinoma in the European Prospective Investigation into Cancer and Nutrition (EPIC). Int J Cancer. 2006;118:728-38. 2:

 

Sex hormone levels in women and breast cancer risk

In the Europe wide EPIC study, women who had higher blood levels of sex hormones including testosterone (male hormones) as well as oestrogen (female hormone) appear to have higher risk of breast cancer. We know that obesity is associated with higher levels of sex hormones and also higher risk of breast cancer in postmenopausal women. If we can identity dietary and other lifestyle factors that influence sex hormone levels in women, this may indicate ways to lower breast cancer risk.

Kaaks R et al. Serum sex steroids in premenopausal women and breast cancer risk within the European Prospective Investigation into Cancer and Nutrition (EPIC). J Natl Cancer Inst 2005;97:755-65.]

Rinaldi S et al. Anthropometric measures, endogenous sex steroids and breast cancer risk in postmenopausal women: A study within the EPIC cohort.
Int J Cancer. 2006;118:2832-9.

 

Dietary sodium and potassium intake and blood pressure

High blood pressure increases risk of stroke and heart attack. High sodium, or salt intake has been associated with increased risk of high blood pressure but it is not clear whether changing salt intake within the usual range that is realistic in the general community is likely to have an influence on blood pressure. In EPIC-Norfolk, men and women who consumed the least salt, (about 5 grams daily), in every day life had lower average blood pressure and were at half the risk of having hypertension (high blood pressure) compared with those who consumed the most amount of salt, (about 10 grams daily). Even within the usual range of salt intake in the community, small and easily achievable reductions in salt intake, e.g. by less than a teaspoon daily, (about 5 grams), may halve a person's chances of getting high blood pressure. In contrast, high dietary intake of potassium, found in plant foods such as fruit and vegetables appears to protect against high blood pressure.

Khaw KT et al. Blood pressure and urinary sodium in men and women: the Norfolk Cohort of the European Prospective Investigation into Cancer (EPIC-Norfolk). Am J Clin Nutr 2004;80:1397-403.

 

Bowel Cancer: High dietary fibre protects against effects of high meat intake

There is a much controversy as to whether high meat intake increases risk of bowel cancer. In the European study, we have found that high dietary fibre intake lowers and high meat intake increases risk of bowel cancer. However, there is an interaction between the different foods. Meat intake increases cancer risk only in those people with low intakes of dietary fibre; high dietary fibre or high fish intake appear to protect against the effects of meat intake and risk of bowel cancer.

Norat T et al. Meat, fish, and colorectal cancer risk: the European Prospective Investigation into cancer and nutrition.J Natl Cancer Inst. 2005;97:906-16.

Bingham SA et al. Dietary fibre in food and protection against colorectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC): an observational study. Lancet 2003;361:1496-501.

 

Eating fruits and vegetables reduces the risk of an early death

We examined the blood levels of vitamin C in almost 20,000 EPIC participants. We found that a rise in the level of vitamin C equivalent to a 50g per day increase in fruit and vegetable consumption could cut the risk of dying early from any cause by 20 per cent. This roughly corresponds to eating an extra apple a day – adding two more daily portions of fruit and vegetables could reduce the risk by as much as half. These findings hold regardless of people's age, blood pressure or whether they smoked.

We also found that men and women with the highest levels of vitamin C were 60 to 70 per cent less likely to die from heart attacks or strokes than those with the lowest levels.

These are some of the largest effects of a small change in diet ever detected. They show that there could be significant health gains from even a small increase in fruit and vegetable consumption.

Published in the Lancet, March 2001 (Lancet 357(9257): 657-663)

 

High impact sports may preserve bone density

We examined data from over 5,000 EPIC participants aged 45-74 who had attended for a second health check. At the check, ultrasound measurements of the heels were made. Low heel bone ultrasound values (low attenuation) are known to be associated with low bone mineral density.
The participants also completed a questionnaire on their physical activity. From this questionnaire, people's recreational activities were classified into four groups according to levels of impact. Activities with no impact included swimming and snooker. Badminton and step aerobics, for example, were classified into the highest impact group.

We found that reported time spent on high impact physical activity was strongly and positively associated with higher ultrasound levels, regardless of people's age and weight. Men who reported taking part in high impact activities for more than two hours a week had around 10% higher ultrasound levels than men who recorded no activity of this type. For women, the high impact group had levels 3% higher, an effect similar in size to an age difference of four years. Women who climbed stairs more often also had higher ultrasound measurements, and those who spent more time watching television had lower levels.

Our results suggest that participation in high impact activities may help preserve bone density and reduce the risk of fracture for people in mid-life. However, this would not be appropriate for older people, who have thinner bones, as these activities could increase the likelihood of falls and fractures.

Published in the British Medical Journal, January 2001 (BMJ 322(7279): 140-146)





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last updated: 20 September 2010