NIHR Signal Being overweight or obese is linked with heart disease even without other metabolic risk factors

Published on 7 November 2017

People with certain metabolic risk factors who are obese are two and a half times as likely to develop heart disease as healthy people of normal weight. But those who are obese without these other risk factors still have a 28% increased risk of heart disease compared with healthy people of normal weight.

This suggests excess weight should be seen as an independent risk factor, challenging the idea that people can be “fat but fit”.

Metabolic risk factors for heart disease cluster together and in this large study the researchers defined “metabolically healthy” as not having; high blood pressure, raised blood sugar, high triglyceride (a type of fat), low HDL “good” cholesterol levels and increased waist measurements.

This large-scale observational research which tracked over 17,000 people in Europe for over 12 years gives us new insights into risk factors for heart disease. Findings suggest that prevention strategies should tackle all risk factors for people who are overweight or obese.

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Why was this study needed?

It is estimated that over 30,000 people die in England because of obesity each year. In 2015, almost two-thirds of adults in England were overweight or obese. The cost of treating people who develop health problems due to obesity is around £6.1 billion a year.

Obese people risk developing medical problems which themselves cause heart disease, such as high blood pressure and type 2 diabetes.

Previously, it was thought that healthy obese people might not have an increased risk of heart disease unless they developed these metabolic risk factors.

In this study, the researchers looked at the effects of being overweight or obese and the cluster of metabolic risks on the chance of heart disease, both separately and in combination. Data came from a random sample of people taking part in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

What did this study do?

This prospective, observational study, EPIC-CVD, followed 17,640 adults from 10 European countries, including the UK. They were aged between 36 and 70 years with no history of a stroke or heart attack.

Participants completed questionnaires about diet, lifestyle, education and medical health. They were classified as metabolically unhealthy if they had three or more of the following: large waist circumference, high blood pressure, high blood glucose, high triglycerides and low HDL (good) cholesterol levels. Their BMI was also calculated at the start of the study. People were then followed up to see who developed coronary heart disease.

This was a large study with a long follow-up time of up to 12.2 years, and we can be confident in the results. Hazard ratios (HR) were appropriately adjusted for a range of factors that could have influenced the results; age, smoking, educational level, physical activity, a diet score, energy, and alcohol intake.

What did it find?

  • Obese people with metabolic risk factors were two and a half times as likely to have heart disease compared with people of normal weight who were metabolically healthy (adjusted HR 2.54, 95% confidence interval [CI] 2.21 to 2.92).
  • Metabolically unhealthy overweight people were more than twice as likely to develop heart disease as healthy people of normal weight (HR 2.33, 95% CI 1.97 to 2.76).
  • Metabolically unhealthy people of normal weight had just over twice the risk of heart disease compared with those who were of normal weight and metabolically healthy (HR 2.15, 95% CI 1.79 to 2.57).
  • Metabolically healthy obese people had a 28% increased risk of heart disease compared with people of normal weight who were metabolically healthy (HR 1.28, 95% CI 1.03 to 1.58).
  • Metabolically healthy overweight people had a 26% increased risk of heart disease compared to healthy people of normal weight (HR 1.26, 95% CI 1.14 to 1.40).

What does current guidance say on this issue?

NICE 2014 guidelines recommend multicomponent lifestyle interventions as the treatment of choice for obesity. Weight management programmes should include behaviour change strategies. Drug treatments are recommended if the BMI is 35 or more. If the person also has other conditions such as type 2 diabetes, or if the BMI is 40 or more then surgical interventions can be considered.

NICE 2016 guidelines recommend healthcare professionals use the QRISK2 tool to assess cardiovascular risk. This is suitable for people up to age 84 years. Lifestyle modifications and taking statins and blood pressure lowering medication can then start as appropriate

What are the implications?

Having metabolic risk factors appears to be a greater risk than being overweight or obese alone. However, people who are obese and overweight and have metabolic risk factors are at the highest risk of heart disease. 

These findings support current guidance recommending healthcare professionals address both obesity and metabolic risk factors as a priority. This would include advice about a healthy diet and exercise with referral to weight management services if more support is needed.

The current NHS health checks offer the chance to get checked for all these risks and the QRISK2 score, used in these, appropriately includes BMI as a continuous and independent risk factor.

Citation and Funding

Lassale C, Tzoulaki I, Moons KGM, et al. Separate and combined associations of obesity and metabolic health with coronary heart disease: a pan-European case-cohort analysis. Eur Heart J. 2017. [Epub ahead of print].

This project was funded by the European Union Framework 7 (HEALTH-F2-2012-279233), the European Research Council (268834), the UK Medical Research Council (G0800270 and MR/L003120/1), the British Heart Foundation (SP/09/002 and RG/08/014 and RG13/13/30194) and the UK National Institute for Health Research.

Bibliography

NHS Choices. Obesity. London: Department of Health; updated 2016.

NHS Choices. Metabolic syndrome. London: Department of Health; updated 2016.

NICE. Cardiovascular disease: risk assessment and reduction, including lipid modification. CG181. London: National Institute for Health and Care Excellence; 2016.

NICE. Obesity prevention. CG43. London: National Institute for Health and Care Excellence; 2015.

NICE. Obesity: identification, assessment and management. CG189. London: National Institute for Health and Care Excellence; 2014.

Public Health England. Guidance. Health matters: obesity and the food environment. Public Health England; 2017.

Why was this study needed?

It is estimated that over 30,000 people die in England because of obesity each year. In 2015, almost two-thirds of adults in England were overweight or obese. The cost of treating people who develop health problems due to obesity is around £6.1 billion a year.

Obese people risk developing medical problems which themselves cause heart disease, such as high blood pressure and type 2 diabetes.

Previously, it was thought that healthy obese people might not have an increased risk of heart disease unless they developed these metabolic risk factors.

In this study, the researchers looked at the effects of being overweight or obese and the cluster of metabolic risks on the chance of heart disease, both separately and in combination. Data came from a random sample of people taking part in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

What did this study do?

This prospective, observational study, EPIC-CVD, followed 17,640 adults from 10 European countries, including the UK. They were aged between 36 and 70 years with no history of a stroke or heart attack.

Participants completed questionnaires about diet, lifestyle, education and medical health. They were classified as metabolically unhealthy if they had three or more of the following: large waist circumference, high blood pressure, high blood glucose, high triglycerides and low HDL (good) cholesterol levels. Their BMI was also calculated at the start of the study. People were then followed up to see who developed coronary heart disease.

This was a large study with a long follow-up time of up to 12.2 years, and we can be confident in the results. Hazard ratios (HR) were appropriately adjusted for a range of factors that could have influenced the results; age, smoking, educational level, physical activity, a diet score, energy, and alcohol intake.

What did it find?

  • Obese people with metabolic risk factors were two and a half times as likely to have heart disease compared with people of normal weight who were metabolically healthy (adjusted HR 2.54, 95% confidence interval [CI] 2.21 to 2.92).
  • Metabolically unhealthy overweight people were more than twice as likely to develop heart disease as healthy people of normal weight (HR 2.33, 95% CI 1.97 to 2.76).
  • Metabolically unhealthy people of normal weight had just over twice the risk of heart disease compared with those who were of normal weight and metabolically healthy (HR 2.15, 95% CI 1.79 to 2.57).
  • Metabolically healthy obese people had a 28% increased risk of heart disease compared with people of normal weight who were metabolically healthy (HR 1.28, 95% CI 1.03 to 1.58).
  • Metabolically healthy overweight people had a 26% increased risk of heart disease compared to healthy people of normal weight (HR 1.26, 95% CI 1.14 to 1.40).

What does current guidance say on this issue?

NICE 2014 guidelines recommend multicomponent lifestyle interventions as the treatment of choice for obesity. Weight management programmes should include behaviour change strategies. Drug treatments are recommended if the BMI is 35 or more. If the person also has other conditions such as type 2 diabetes, or if the BMI is 40 or more then surgical interventions can be considered.

NICE 2016 guidelines recommend healthcare professionals use the QRISK2 tool to assess cardiovascular risk. This is suitable for people up to age 84 years. Lifestyle modifications and taking statins and blood pressure lowering medication can then start as appropriate

What are the implications?

Having metabolic risk factors appears to be a greater risk than being overweight or obese alone. However, people who are obese and overweight and have metabolic risk factors are at the highest risk of heart disease. 

These findings support current guidance recommending healthcare professionals address both obesity and metabolic risk factors as a priority. This would include advice about a healthy diet and exercise with referral to weight management services if more support is needed.

The current NHS health checks offer the chance to get checked for all these risks and the QRISK2 score, used in these, appropriately includes BMI as a continuous and independent risk factor.

Citation and Funding

Lassale C, Tzoulaki I, Moons KGM, et al. Separate and combined associations of obesity and metabolic health with coronary heart disease: a pan-European case-cohort analysis. Eur Heart J. 2017. [Epub ahead of print].

This project was funded by the European Union Framework 7 (HEALTH-F2-2012-279233), the European Research Council (268834), the UK Medical Research Council (G0800270 and MR/L003120/1), the British Heart Foundation (SP/09/002 and RG/08/014 and RG13/13/30194) and the UK National Institute for Health Research.

Bibliography

NHS Choices. Obesity. London: Department of Health; updated 2016.

NHS Choices. Metabolic syndrome. London: Department of Health; updated 2016.

NICE. Cardiovascular disease: risk assessment and reduction, including lipid modification. CG181. London: National Institute for Health and Care Excellence; 2016.

NICE. Obesity prevention. CG43. London: National Institute for Health and Care Excellence; 2015.

NICE. Obesity: identification, assessment and management. CG189. London: National Institute for Health and Care Excellence; 2014.

Public Health England. Guidance. Health matters: obesity and the food environment. Public Health England; 2017.

Separate and combined associations of obesity and metabolic health with coronary heart disease: a pan-European case-cohort analysis

Published on 14 August 2017

C Lassale, I Tzoulaki, K. Moons, M Sweeting, J Boer, L Johnson, J M Huerta, C Agnoli, H Freisling, E Weiderpass P Wennberg, D L. van der A, L Arriola, V Benetou, H Boeing, F Bonnet, S. Colorado-Yohar, G Engström, A Eriksen, P Ferrari, S Grioni, M Johansson, R Kaaks, M Katsoulis, V Katzke, T Key, G Matullo, O Melander, Elena Molina-Portillo, Concepción Moreno-Iribas, Margareta Norberg, Kim Overvad, Salvatore Panico, J. Ramón Quirós, Calogero Saieva, Guri Skeie, Annika Steffen, M Stepien, A Tjønneland, A Trichopoulou, R Tumino, Y van der Schouw, M Verschuren, C Langenberg, E Di Angelantonio, E Riboli, N Wareham, J Danesh, A. Butterworth

European Heart Journal , 2017

Aims The hypothesis of ‘metabolically healthy obesity’ implies that, in the absence of metabolic dysfunction, individuals with excess adiposity are not at greater cardiovascular risk. We tested this hypothesis in a large pan-European prospective study. Methods and results We conducted a case-cohort analysis in the 520 000-person European Prospective Investigation into Cancer and Nutrition study (‘EPIC-CVD’). During a median follow-up of 12.2 years, we recorded 7637 incident coronary heart disease (CHD) cases. Using cut-offs recommended by guidelines, we defined obesity and overweight using body mass index (BMI), and metabolic dysfunction (‘unhealthy’) as ≥ 3 of elevated blood pressure, hypertriglyceridaemia, low HDL-cholesterol, hyperglycaemia, and elevated waist circumference. We calculated hazard ratios (HRs) and 95% confidence intervals (95% CI) within each country using Prentice-weighted Cox proportional hazard regressions, accounting for age, sex, centre, education, smoking, diet, and physical activity. Compared with metabolically healthy normal weight people (reference), HRs were 2.15 (95% CI: 1.79; 2.57) for unhealthy normal weight, 2.33 (1.97; 2.76) for unhealthy overweight, and 2.54 (2.21; 2.92) for unhealthy obese people. Compared with the reference group, HRs were 1.26 (1.14; 1.40) and 1.28 (1.03; 1.58) for metabolically healthy overweight and obese people, respectively. These results were robust to various sensitivity analyses. Conclusion Irrespective of BMI, metabolically unhealthy individuals had higher CHD risk than their healthy counterparts. Conversely, irrespective of metabolic health, overweight and obese people had higher CHD risk than lean people. These findings challenge the concept of ‘metabolically healthy obesity’, encouraging population-wide strategies to tackle obesity.

The researchers defined obesity as a body mass index (BMI)> 30kg/m2 and being overweight as 25-30kg/m2. They defined metabolic syndrome as three or more of the following: high blood pressure, high waist circumference, raised triglyceride levels, raised blood sugar levels, and/or taking treatment for these conditions, and/or a self-reported history of these conditions.

Expert commentary

This study adds to the robust evidence base on the risks of excess weight. Importantly, it demonstrates that irrespective of being metabolically healthy, individuals who are overweight or obese are still at an increased risk of cardiovascular disease compared to those with a healthy weight.

It reminds us of the importance of being a healthy weight, but we know there is no simple solution. Public Health England is taking action across the system to support people to achieve a healthier weight, including challenging industry to remove sugar and calories from the foods we eat.

Dr Alison Tedstone, National Director for Obesity, Public Health England