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The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome
p u b l i c h e a l t h x x x ( 2 0 1 6 ) 1 e5
Available online at www.sciencedirect.com
Public Health journal homepage: www.elsevier.com/puhe
Original Research
The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome D. Kim a, S.-J. Yoon a,*, D.-S. Lim b, Y.-H. Gong a, S. Ko a, Y.-H. Lee a, H.S. Lee c, M.-S. Park c, K.-H. Kim d, Y.A. Kim e a
Department of Preventive Medicine, Korea University College of Medicine, Seoul, Republic of Korea Department of Cardiology, Korea University Anam Hospital, Seoul, Republic of Korea c Metabolic Syndrome Management Center of Seoul Metropolitan Government, Seoul, Republic of Korea d Health Insurance Review & Assessment Service, Seoul, Republic of Korea e Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea b
article info
abstract
Article history:
Objectives: Metabolic syndrome (MS), as a precursor of diabetes mellitus (DM) and cardio-
Received 28 October 2015
vascular disease, is increasing steadily worldwide. We examined the preventive effects of
Received in revised form
lifestyle intervention on the occurrence of DM and acute myocardial infarction (AMI) in MS.
13 April 2016
Study design: Observational study on disease occurrence after lifestyle intervention.
Accepted 10 June 2016
Methods: The lifestyle intervention was administered to subjects with MS participating in a
Available online xxx
metropolitan lifestyle intervention program for 1 year. The same numbers of nonparticipating age- and sex-matched subjects with MS were randomly extracted from na-
Keywords:
tional health examination data. After intervention or examination, new occurrences of
Metabolic syndrome
hypertension, DM, and AMI were identified through the national health insurance claims
Lifestyle intervention
data during 1 year. For DM and AMI, multivariate logistic regression analysis for the factors
Diabetes mellitus
affecting each disease was performed.
Acute myocardial infarction
Results: In the intervention group and the control group (14,918 in each group), the occurrence of hypertension was 555 (6.07%) and 751 (8.33%), the occurrence of DM was 324 (2.55%) and 488 (3.89%), the occurrence of dyslipidemia was 321 (2.59%) and 373 (2.72%), and the occurrence of AMI was 13 (0.09%) and 26 (0.17%), respectively. In multivariate logistic regression analysis, adjusted odds ratios for intervention were 0.752 (95% confidence interval [CI]: 0.644e0.879) and 0.499 (95% CI: 0.251e0.992) for DM and AMI, respectively, indicating that lifestyle intervention has a preventive effect. Conclusions: Lifestyle intervention in MS has preventive effects on the occurrence of DM and AMI, and long-term follow-up is needed to evaluate these preventive effects in more detail. © 2016 Published by Elsevier Ltd on behalf of The Royal Society for Public Health.
* Corresponding author. E-mail address: [email protected] (S.-J. Yoon). http://dx.doi.org/10.1016/j.puhe.2016.06.012 0033-3506/© 2016 Published by Elsevier Ltd on behalf of The Royal Society for Public Health. Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
2
p u b l i c h e a l t h x x x ( 2 0 1 6 ) 1 e5
Introduction Metabolic syndrome (MS) is a comprehensive term encompassing diabetes mellitus (DM), hypertension, obesity, and dyslipidemia. The prevalence of MS is increasing steadily worldwide, and Korea is not an exception.1 MS is a precursor of DM2 and cardiovascular disease (CVD) and increases the risk of incident cardiovascular events and death.3 As the burden of disease due to acute myocardial infarction (AMI) and the resulting economic burden have increased,4,5 comprehensive management of MS is necessary. Lifestyle intervention aims to improve the metabolic parameters through diet, exercise, and education, and many studies regarding the effects of lifestyle intervention on MS have been reported. A recent meta-analysis further strengthens the evidence that long-term regular lifestyle intervention reduces the prevalence of MS and abnormalities associated with MS and may be a useful tool in reducing the future occurrence of MS.6 Of course, these positive results mean that the intervention improve the metabolic parameters but more important than that is whether these interventions are effective in the prevention of complications of MS such as DM, hypertension, and ischaemic heart disease. In subjects with impaired glucose tolerance (IGT), several studies have reported the prevention of MS7,8 or DM9,10 as well as improvement in the risk factors of CVD11 through lifestyle intervention, but there is little research on the prevention of DM or AMI in MS. In South Korea, the MS management projects are underway in many local health centres under the awareness of the importance of MS, and the design and preliminary results have been announced previously.12 Therefore, we evaluated the preventive effects of lifestyle intervention on the occurrence of DM and AMI in MS by a metropolitan lifestyle intervention program.
Methods Study population Korean adults aged 30 years and older with MS were enrolled among the subjects participating in a metropolitan lifestyle intervention program for city residents aimed at decreasing the risk of MS from January 2009 to December 2012. MS was defined with the widely used National Cholesterol Education Program e Adult Treatment Panel III guidelines.13 However, for the waist circumference in consideration of the characteristics of the Korean, it was applied with the recommendations of the Korean Society for the Study of Obesity.14,15 Therefore, the subjects who have three or more of the following five criteria were classified in MS in this study: (1) abdominal obesity (waist circumference > 90 cm for men or > 85 cm for women); (2) triglycerides (TG) 150 mg/dl or receiving drug treatment; (3) high-density lipoprotein cholesterol (HDL-C) < 40 mg/dl for men or < 50 mg/dl for women or receiving drug treatment; (4) systolic blood pressure (SBP)/diastolic blood pressure (DBP) 130/85 mmHg or
receiving drug treatment; and (5) fasting plasma glucose 100 mg/dl or receiving drug treatment. The intervention program has been described previously.12 In brief, face-to-face lifestyle counselling on diet, physical activity, smoking, and alcohol consumption was provided monthly to the subjects with MS in the Public Health Centre for 12 months. For diet, dietary counselling was provided by dietitians and consisted of an inquiry into dietary history, a nutrition regimen, and regular monitoring. Dietary history was collected through a 24-h recall method and a weekly meal diary. Diet regimen was developed according to each subject's major health and dietary problems. For physical activity, exercise specialists conducted physical activity counselling sessions. A subject's physical activity was determined every session using a standardized physical activity questionnaire, which takes into account and sums up all physical activities from the three areas of exercise, domestic chores, and vocational activity, on a weekly basis by intensity and duration. To monitor the five risk factors of MS and changes in lifestyle, the intervention group was reassessed every 3 months. Most South Korean adults possess their own mobile phones; so, one health tip text message was sent out once per week, a message encouraging further efforts was sent out once a month, and a message notifying the subject of upcoming visits was also sent out once a month. For the control group, the national health examination data were utilized. In South Korea, health examinations are implemented for white-collar workers every 2 years and for non-white-collar workers annually. The examination includes medical history, smoking and drinking habits, and metabolic factors that can determine MS, such as waist circumference (WC), SBP, DBP, and fasting blood glucose (FBG), HDL-C, and TG levels. After collecting the national health examination data of Seoul citizens aged 30 years and older from January 2009 to December 2009, we excluded the participants by using the Resident Registration Number. Then, we randomly extracted the same number of subjects matched for age and sex with the intervention group. All subjects fasted for 10 h before being tested for the five metabolic factors of MS: waist circumference; blood pressure; plasma glucose; TG; and HDL-C. Serum TG and HDL-C levels were determined by enzymatic methods with a chemistry analyser. Plasma glucose was measured with the glucose oxidase method.
Measuring the occurrence of disease To identify the occurrence of MS-related diseases, we requested the claims data with the International Classification of Disease tenth revision codes from the National Health Insurance Service between 2009 and 2014. For the intervention group, the claims with hypertension (I10-15), DM (E10-14), dyslipidemia (E78), and AMI (I21) were extracted during a period of 1 year before and after the intervention. For the control group, the same claims were extracted during a period of 1 year before and after the health examination. The occurrence of hypertension, DM, and dyslipidemia was defined as a subject with one inpatient admission or more than three outpatient visits within 1 year after the intervention or the health examination among the subjects with no claim within 1 year before the intervention or the health examination. Meanwhile, the occurrence of AMI was defined as
Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
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p u b l i c h e a l t h x x x ( 2 0 1 6 ) 1 e5
a subject with a claim with an admission or outpatient visit during the same period, considering the severity of disease.
Table 2 e Changes in metabolic risk factors before and after lifestyle intervention in the intervention group. Risk factors
Statistical analysis
Metabolic syndrome (n ¼ 14,918) Before
The changes in metabolic risk factor values and the average number of retained risk factors between baseline and the 12month re-examination in the intervention group were evaluated using paired t-tests for significance. For differences in occurrence of hypertension, DM, dyslipidemia, and AMI between the intervention group and the control group, Chisquared tests were conducted. For DM and AMI, multivariate logistic regression analysis was performed for factors that were significant in the univariate analysis or affected the occurrence of each disease. SAS version 9.4 (SAS Institute Inc., Cary, NC, USA) was used for all data collection and statistical analyses.
WC (cm) SBP (mmHg) DBP (mmHg) FBG (mg/dl) TG (mg/dl) HDL-C (mg/dl) Average no. of retained metabolic risk factors
87.9 ± 7.8 131.6 ± 15.5 81.7 ± 10.8 107.7 ± 25.9 188.4 ± 94.7 44.0 ± 12.6 3.6 ± 0.7
After 86.6 126.8 79.1 103.5 161.5 46.0 2.9
± 7.7 ± 14.0 ± 9.7 ± 22.0 ± 84.9 ± 12.4 ± 1.3
Difference P-value 1.26 4.85 2.58 4.21 26.89 þ2.02 0.74
<0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
WC: waist circumference; SBP: systolic blood pressure; DBP: diastolic blood pressure; FBG: fasting blood glucose; TG: triglyceride; HDL-C: high-density lipoprotein cholesterol.
Results Baseline characteristics
Effects of the lifestyle intervention
Among the 38,424 subjects participating in the intervention program and receiving follow-up examination after 12 months, 14,918 (38.8%) had MS. Of the 196,470 Seoul citizens aged 30 years and older with national health examination data and not participating in the intervention program, 50,283 (25.6%) had MS. From these non-participants, 14,918 for the control group were randomly extracted matched for age and sex to the intervention group. The clinical and laboratory characteristics of these 29,836 subjects are described in Table 1.
After 1 year of intervention, the individuals in the intervention group showed statistically significant improvements in all five risk factors, and the average number of retained risk factors decreased (Table 2.). The occurrence of hypertension was 555 (6.07%) and 751 (8.33%) and the occurrence of dyslipidemia was 321 (2.59%) and 373 (2.72%) in the intervention group and the control group, respectively. The occurrence of DM and AMI was significantly less in the intervention group than in the control group: 324 (2.55%) and 488 (3.89%) for DM and 13 (0.09%) and 26 (0.17%) for AMI, respectively (Table 3). In a similar analysis of 23,506 participants without MS and 23,506 randomly extracted age- and sex-matched non-participants without MS, the occurrence of DM and AMI was two to six times lower in those without MS than in those with MS: 140 (0.62%) and 149 (0.66%) for DM and 13 (0.06%) and 14 (0.06%) for AMI, respectively. In multivariate logistic regression analysis for the factors that were significant in the univariate analysis or affected the occurrence of DM, lifestyle intervention showed a preventive effect on the occurrence of DM with statistical significance with an adjusted odds ratio (OR) for intervention of 0.752 (95% confidence interval [CI]: 0.644e0.879). The analysis for AMI also showed a preventive effect with an adjusted OR of 0.499 (95% CI: 0.251e0.992) (Table 4). In multivariate logistic regression analysis for hypertension and dyslipidemia, lifestyle intervention did not show a preventive effect on the occurrence of disease with statistical significance.
Table 1 e Clinical and laboratory baseline characteristics of the subjects. Characteristics
Age (years) Men (%) Height (cm) Weight (kg) BMI (kg/m2) Non-smoking (%) Non-consumption of alcohol (%) Diagnosis history (%) Hypertension Diabetes mellitus Dyslipidemia WC (cm) SBP (mmHg) DBP (mmHg) FBG (mg/dl) TG (mg/dl) HDL-C (mg/dl) Average no. of retained metabolic risk factors
Intervention group (n ¼ 14,918)
Control group (n ¼ 14,918)
58.0 ± 9.1 37.6 160.6 ± 8.6 66.3 ± 10.9 25.6 ± 3.1 73.7 47.5
58.2 ± 9.2 37.6 160.2 ± 8.8 67.2 ± 11.2 26.1 ± 3.2 68.9 62.3
40.0 13.5 29.2 87.9 ± 7.9 131.6 ± 15.5 81.7 ± 10.8 107.7 ± 25.9 187.8 ± 94.3 43.8 ± 12.6 3.6 ± 0.7
44.3 17.8 14.7 86.9 ± 8.2 132.0 ± 14.5 81.0 ± 10.1 112.0 ± 30.6 187.6 ± 93.8 48.7 ± 11.7 3.5 ± 0.7
BMI: body mass index; WC: waist circumference; SBP: systolic blood pressure; DBP: diastolic blood pressure; FBG: fasting blood glucose; TG: triglyceride; HDL-C: high-density lipoprotein cholesterol.
Discussion There have been many lifestyle intervention programs for MS or IGT in several communities. For the effect of these programs, previous studies evaluated the reduced number of metabolic factors, the decreased rate of MS, and the changes
Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
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Table 3 e New occurrence of diseases according to participation. Metabolic syndrome (n ¼ 29,836)
Disease
P-value
Intervention group (n ¼ 14,918)
Control group (n ¼ 14,918)
New occurrence/non-patients (%)
New occurrence/non-patients (%)
555/ 9139 (6.1) 324/12,729 (2.6) 321/12,372 (2.6) 13/14,882 (0.1)
751/ 9011 (8.3) 488/12,537 (3.9) 373/13,696 (2.7) 26/14,881 (0.2)
Hypertension DM Dyslipidemia AMI
<0.001 <0.001 0.519 0.037
OR (95% CI)
1.41 1.55 1.05 2.00
(1.26e1.56) (1.34e1.79) (0.90e1.22) (1.03e3.90)
OR: odds ratio; CI: confidence interval; DM: diabetes mellitus; AMI: acute myocardial infarction.
in such indicators related to cardiovascular complications before and after the intervention. In this study, we found that the metabolic factors were improved and the average number of retained risk factors decreased. Although IGT is one of the components of the MS, and lifestyle intervention affects the common effect on the subjects with MS or IGT, to evaluate the preventive effects of lifestyle intervention in MS is more important in establishing appropriate healthcare policies. There are many studies about the associations between MS and hypertension, DM, and AMI, and the preventive effects of lifestyle intervention on the occurrence of DM in subjects with IGT have already been proven. However, few studies have assessed the occurrence of these diseases according to lifestyle intervention in MS without each disease. In particular, a study reported that lifestyle intervention improved CVD risk factor status, but no differences in CVD events were noted in IGT.11 Therefore, it is important to assess the occurrence of AMI, one of the most serious cardiovascular events, with respect to lifestyle intervention. In this study, the claims data from the National Health Insurance Service were used to identify the occurrence of hypertension, DM, dyslipidemia, and AMI. South Korea has a single health insurance system, and health check-ups target the entire population every 1 or 2 years. Moreover, Koreans may visit clinics frequently owing to the lower threshold for primary health care institutions and can easily receive medical consultations or examinations. Therefore, considering the new occurrence of non-communicable diseases such as hypertension, DM, and dyslipidemia as one visit can result in overestimation. Therefore, occurrence was defined as a subject with one inpatient admission or more than three outpatient visits for these diseases.16 In our study, considering a case as a claim with any admission or outpatient visit, the occurrence of hypertension was 838 (9.17%) and 1239 (13.75%), the occurrence of DM was 649 (5.1%) and 936 (7.47%), and the occurrence of dyslipidemia was 946 (7.65%) and 1296 (9.46%) in
the intervention group and the control group, respectively, all with statistical significance. It is assumed for this reason that the occurrence of DM within 1 year after the intervention or the health examination was somewhat lower than that of other studies.9,10 Meanwhile, the occurrence of AMI was defined as a subject with a claim with admission or outpatient visit, considering the severity of the disease, as the accuracy for diagnosing AMI in Korean National Medical Health Insurance claims data is over 70%, and reliability is fair to good.17 However, even if the occurrence was defined as the subject with more than one inpatient admission, considering the limitation of the claims data, AMI occurred significantly less in the intervention group than in the control group (P ¼ 0.033). In multivariate logistic regression analysis for the factors that were significant in the univariate analysis or affected the occurrence of DM,18 such as participation in a lifestyle intervention program, sex, age, FBG, WC, and average number of retained metabolic risk factors, a preventive effect on the occurrence of DM was shown. A more active and tailored intervention is needed for subjects with higher FBG levels and WC at the time of MS diagnosis to affect the occurrence of DM. In multivariate logistic regression analysis for the factors affecting the occurrence of AMI,19 such as participation in a lifestyle intervention program, sex, diagnosis or history of hypertension and DM, and smoking, a preventive effect on the occurrence of AMI was also shown. In this study, we selected 50,283 subjects with MS among 196,470 non-participants for controls. The mean of age of these subjects with MS was 56.7 years, and the proportion of men was 56.6%. Therefore, we randomly extracted the same number as individual in intervention group with matching age and sex. For these 50,283 subjects with MS, the occurrence of DM and AMI was 1518/42,541 (3.57%) and 80/50,151 (0.16%), respectively. As limitations of the study, the participants enrolled in the metropolitan lifestyle intervention program were not a random sample; so, the preventive effects of lifestyle
Table 4 e Multivariate logistic regression analysis in new occurrence of DM and AMI. Disease DM AMI
Intervention No Yes No Yes
No. of new occurrences (%) 488 324 26 13
(3.9) (2.6) (0.2) (0.1)
Crude OR 1.00 0.65 1.00 0.50
95% CI
P-value
0.56e0.74
<0.001
0.26e0.97
0.041
Adjusted OR 1.00 0.75a 1.00 0.50b
95% CI
P-value
0.64e0.88
<0.001
0.25e0.99
0.048
OR: odds ratio; CI: confidence interval; DM: diabetes mellitus; AMI: acute myocardial infarction. a Adjusted for participation, sex, age, fasting blood glucose, waist circumference, and average number of retained metabolic risk factors in DM. b Adjusted for participation, sex, age, diagnosis history of hypertension and DM, smoking, and AMI.
Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
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intervention may be overestimated. However, it is difficult to determine whether the intervention after random sampling while operating a public education program as it has already been demonstrated that the lifestyle intervention improve the metabolic parameters. We confirmed that the average number of retained risk factors decreased after lifestyle intervention in the intervention group, but we did not observe the laboratory characteristics of the control group after 1 year. This is a limitation of our study, but because other studies showed no change or a tendency to become worse in the control group, we supposed the control group would show similar results.8,12 Another important limitation is that study follow-up for the occurrence of the diseases was limited to 1 year despite an interim report. Continuous follow-up is needed to evaluate long-term effects. In addition, because the national health examination data do not have the entry for the educational and economic levels, there is a limit to grasp socio-economic status. Despite its limitations, this was a large-scale research study with controls to assess the preventive effects of lifestyle intervention on the occurrence of DM and AMI in MS. Moreover, the effect may be expected to be greater considering the healthy volunteer effect20 in control group with health examination data, and this result will help in establishing community health programs.
Author statements
5.
6.
7.
8.
9.
10.
11.
12.
Ethical approval The study protocol was approved by the institutional review board of Korea University (1040548-KU-IRB-13-118-A-1).
13.
Funding This study was supported by a grant from the National R&D Program for Cancer Control, Ministry of Health and Welfare, Korea (grant no. 1320310).
14.
Competing interests 15.
The authors have not declared any conflicts of interest.
references
1. Lim S, Shin H, Song JH, Kwak SH, Kang SM, Yoon JW, et al. Increasing prevalence of metabolic syndrome in Korea: the Korean National Health and Nutrition Examination Survey for 1998e2007. Diabetes Care 2011;34:1323e8. 2. Wilson PW, D'Agostino RB, Parise H, Sullivan L, Meigs JB. Metabolic syndrome as a precursor of cardiovascular disease and type 2 diabetes mellitus. Circulation 2005;112:3066e72. 3. Gami AS, Witt BJ, Howard DE, Erwin PJ, Gami LA, Somers VK, et al. Metabolic syndrome and risk of incident cardiovascular events and death: a systematic review and meta-analysis of longitudinal studies. J Am Coll Cardiol 2007;49:403e14. 4. Lozano R, Naghavi M, Foreman K, Lim S, Shibuya K, Aboyans V, et al. Global and regional mortality from 235
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causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2013;380:2095e128. Seo H, Yoon S-J, Yoon J, Kim D, Gong Y, Kim AR, et al. Recent trends in economic burden of acute myocardial infarction in South Korea. PLoS One 2015;10. Yamaoka K, Tango T. Effects of lifestyle modification on metabolic syndrome: a systematic review and meta-analysis. BMC Med 2012;10:138. Orchard TJ, Temprosa M, Goldberg R, Haffner S, Ratner R, Marcovina S, et al. The effect of metformin and intensive lifestyle intervention on the metabolic syndrome: the Diabetes Prevention Program randomized trial. Ann Intern Med 2005;142:611e9. € m J, Peltonen M, Ilanne-Parikka P, Eriksson JG, Lindstro € ma € la € inen H, et al. Effect of lifestyle intervention Aunola S, Ha on the occurrence of metabolic syndrome and its components in the Finnish Diabetes Prevention Study. Diabetes Care 2008;31:805e7. Knowler WC, Barrett-Connor E, Fowler SE, Hamman RF, Lachin JM, Walker EA, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002;346:393e403. Ramachandran A, Snehalatha C, Mary S, Mukesh B, Bhaskar A, Vijay V. The Indian Diabetes Prevention Programme shows that lifestyle modification and metformin prevent type 2 diabetes in Asian Indian subjects with impaired glucose tolerance (IDPP-1). Diabetologia 2006;49:289e97. Orchard M, Fowler S, Temprosa M. Impact of intensive lifestyle and metformin therapy on cardiovascular disease risk factors in the diabetes prevention program. Diabetes Care 2005;28:888e94. Lee YH, Yoon SJ, Kim HS, Oh SW, Ryu HS, Choo JA, et al. Design and preliminary results of a metropolitan lifestyle intervention program for people with metabolic syndrome in South Korea. Diabetes Res Clin Pract 2013;101:293e302. Expert Panel on Detection E. Executive summary of the Third Report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III). JAMA 2001;285:2486. Yoon Y, Lee E, Park C, Lee S, Oh S. The new definition of metabolic syndrome by the international diabetes federation is less likely to identify metabolically abnormal but nonobese individuals than the definition by the revised national cholesterol education program: the Korea NHANES study. Int J Obes 2007;31:528e34. Lee S, Park HS, Kim SM, Kwon HS, Kim DY, Kim DJ, et al. Cut-off points of waist circumference for defining abdominal obesity in the Korean population. Korean J Obes 2006;15:1e9. Kim E-J, Yoon S-J, Jo M-W, Kim H-J. Measuring the burden of chronic diseases in Korea in 2007. Public Health 2013;127:806e13. Kimm H, Yun JE, Lee SH, Jang Y, Jee SH. Validity of the diagnosis of acute myocardial infarction in Korean national medical health insurance claims data: the Korean heart study (1). Korean Circ J 2012;42:10e5. Melmed S, Polonsky KS, Larsen PR, Kronenberg HM. Williams textbook of endocrinology. 12th edn. Philadelphia Saunders Elsevier; 20111372. Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's heart disease: a textbook of cardiovascular medicine. 9th edn. Philadelphia: Saunders Elsevier; 2012914. Lindsted KD, Fraser GE, Steinkohl M, Beeson WL. Healthy volunteer effect in a cohort study: temporal resolution in the Adventist Health Study. J Clin Epidemiol 1996;49:783e90.
Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
Available online at www.sciencedirect.com
Public Health journal homepage: www.elsevier.com/puhe
Original Research
The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome D. Kim a, S.-J. Yoon a,*, D.-S. Lim b, Y.-H. Gong a, S. Ko a, Y.-H. Lee a, H.S. Lee c, M.-S. Park c, K.-H. Kim d, Y.A. Kim e a
Department of Preventive Medicine, Korea University College of Medicine, Seoul, Republic of Korea Department of Cardiology, Korea University Anam Hospital, Seoul, Republic of Korea c Metabolic Syndrome Management Center of Seoul Metropolitan Government, Seoul, Republic of Korea d Health Insurance Review & Assessment Service, Seoul, Republic of Korea e Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea b
article info
abstract
Article history:
Objectives: Metabolic syndrome (MS), as a precursor of diabetes mellitus (DM) and cardio-
Received 28 October 2015
vascular disease, is increasing steadily worldwide. We examined the preventive effects of
Received in revised form
lifestyle intervention on the occurrence of DM and acute myocardial infarction (AMI) in MS.
13 April 2016
Study design: Observational study on disease occurrence after lifestyle intervention.
Accepted 10 June 2016
Methods: The lifestyle intervention was administered to subjects with MS participating in a
Available online xxx
metropolitan lifestyle intervention program for 1 year. The same numbers of nonparticipating age- and sex-matched subjects with MS were randomly extracted from na-
Keywords:
tional health examination data. After intervention or examination, new occurrences of
Metabolic syndrome
hypertension, DM, and AMI were identified through the national health insurance claims
Lifestyle intervention
data during 1 year. For DM and AMI, multivariate logistic regression analysis for the factors
Diabetes mellitus
affecting each disease was performed.
Acute myocardial infarction
Results: In the intervention group and the control group (14,918 in each group), the occurrence of hypertension was 555 (6.07%) and 751 (8.33%), the occurrence of DM was 324 (2.55%) and 488 (3.89%), the occurrence of dyslipidemia was 321 (2.59%) and 373 (2.72%), and the occurrence of AMI was 13 (0.09%) and 26 (0.17%), respectively. In multivariate logistic regression analysis, adjusted odds ratios for intervention were 0.752 (95% confidence interval [CI]: 0.644e0.879) and 0.499 (95% CI: 0.251e0.992) for DM and AMI, respectively, indicating that lifestyle intervention has a preventive effect. Conclusions: Lifestyle intervention in MS has preventive effects on the occurrence of DM and AMI, and long-term follow-up is needed to evaluate these preventive effects in more detail. © 2016 Published by Elsevier Ltd on behalf of The Royal Society for Public Health.
* Corresponding author. E-mail address: [email protected] (S.-J. Yoon). http://dx.doi.org/10.1016/j.puhe.2016.06.012 0033-3506/© 2016 Published by Elsevier Ltd on behalf of The Royal Society for Public Health. Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
2
p u b l i c h e a l t h x x x ( 2 0 1 6 ) 1 e5
Introduction Metabolic syndrome (MS) is a comprehensive term encompassing diabetes mellitus (DM), hypertension, obesity, and dyslipidemia. The prevalence of MS is increasing steadily worldwide, and Korea is not an exception.1 MS is a precursor of DM2 and cardiovascular disease (CVD) and increases the risk of incident cardiovascular events and death.3 As the burden of disease due to acute myocardial infarction (AMI) and the resulting economic burden have increased,4,5 comprehensive management of MS is necessary. Lifestyle intervention aims to improve the metabolic parameters through diet, exercise, and education, and many studies regarding the effects of lifestyle intervention on MS have been reported. A recent meta-analysis further strengthens the evidence that long-term regular lifestyle intervention reduces the prevalence of MS and abnormalities associated with MS and may be a useful tool in reducing the future occurrence of MS.6 Of course, these positive results mean that the intervention improve the metabolic parameters but more important than that is whether these interventions are effective in the prevention of complications of MS such as DM, hypertension, and ischaemic heart disease. In subjects with impaired glucose tolerance (IGT), several studies have reported the prevention of MS7,8 or DM9,10 as well as improvement in the risk factors of CVD11 through lifestyle intervention, but there is little research on the prevention of DM or AMI in MS. In South Korea, the MS management projects are underway in many local health centres under the awareness of the importance of MS, and the design and preliminary results have been announced previously.12 Therefore, we evaluated the preventive effects of lifestyle intervention on the occurrence of DM and AMI in MS by a metropolitan lifestyle intervention program.
Methods Study population Korean adults aged 30 years and older with MS were enrolled among the subjects participating in a metropolitan lifestyle intervention program for city residents aimed at decreasing the risk of MS from January 2009 to December 2012. MS was defined with the widely used National Cholesterol Education Program e Adult Treatment Panel III guidelines.13 However, for the waist circumference in consideration of the characteristics of the Korean, it was applied with the recommendations of the Korean Society for the Study of Obesity.14,15 Therefore, the subjects who have three or more of the following five criteria were classified in MS in this study: (1) abdominal obesity (waist circumference > 90 cm for men or > 85 cm for women); (2) triglycerides (TG) 150 mg/dl or receiving drug treatment; (3) high-density lipoprotein cholesterol (HDL-C) < 40 mg/dl for men or < 50 mg/dl for women or receiving drug treatment; (4) systolic blood pressure (SBP)/diastolic blood pressure (DBP) 130/85 mmHg or
receiving drug treatment; and (5) fasting plasma glucose 100 mg/dl or receiving drug treatment. The intervention program has been described previously.12 In brief, face-to-face lifestyle counselling on diet, physical activity, smoking, and alcohol consumption was provided monthly to the subjects with MS in the Public Health Centre for 12 months. For diet, dietary counselling was provided by dietitians and consisted of an inquiry into dietary history, a nutrition regimen, and regular monitoring. Dietary history was collected through a 24-h recall method and a weekly meal diary. Diet regimen was developed according to each subject's major health and dietary problems. For physical activity, exercise specialists conducted physical activity counselling sessions. A subject's physical activity was determined every session using a standardized physical activity questionnaire, which takes into account and sums up all physical activities from the three areas of exercise, domestic chores, and vocational activity, on a weekly basis by intensity and duration. To monitor the five risk factors of MS and changes in lifestyle, the intervention group was reassessed every 3 months. Most South Korean adults possess their own mobile phones; so, one health tip text message was sent out once per week, a message encouraging further efforts was sent out once a month, and a message notifying the subject of upcoming visits was also sent out once a month. For the control group, the national health examination data were utilized. In South Korea, health examinations are implemented for white-collar workers every 2 years and for non-white-collar workers annually. The examination includes medical history, smoking and drinking habits, and metabolic factors that can determine MS, such as waist circumference (WC), SBP, DBP, and fasting blood glucose (FBG), HDL-C, and TG levels. After collecting the national health examination data of Seoul citizens aged 30 years and older from January 2009 to December 2009, we excluded the participants by using the Resident Registration Number. Then, we randomly extracted the same number of subjects matched for age and sex with the intervention group. All subjects fasted for 10 h before being tested for the five metabolic factors of MS: waist circumference; blood pressure; plasma glucose; TG; and HDL-C. Serum TG and HDL-C levels were determined by enzymatic methods with a chemistry analyser. Plasma glucose was measured with the glucose oxidase method.
Measuring the occurrence of disease To identify the occurrence of MS-related diseases, we requested the claims data with the International Classification of Disease tenth revision codes from the National Health Insurance Service between 2009 and 2014. For the intervention group, the claims with hypertension (I10-15), DM (E10-14), dyslipidemia (E78), and AMI (I21) were extracted during a period of 1 year before and after the intervention. For the control group, the same claims were extracted during a period of 1 year before and after the health examination. The occurrence of hypertension, DM, and dyslipidemia was defined as a subject with one inpatient admission or more than three outpatient visits within 1 year after the intervention or the health examination among the subjects with no claim within 1 year before the intervention or the health examination. Meanwhile, the occurrence of AMI was defined as
Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
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a subject with a claim with an admission or outpatient visit during the same period, considering the severity of disease.
Table 2 e Changes in metabolic risk factors before and after lifestyle intervention in the intervention group. Risk factors
Statistical analysis
Metabolic syndrome (n ¼ 14,918) Before
The changes in metabolic risk factor values and the average number of retained risk factors between baseline and the 12month re-examination in the intervention group were evaluated using paired t-tests for significance. For differences in occurrence of hypertension, DM, dyslipidemia, and AMI between the intervention group and the control group, Chisquared tests were conducted. For DM and AMI, multivariate logistic regression analysis was performed for factors that were significant in the univariate analysis or affected the occurrence of each disease. SAS version 9.4 (SAS Institute Inc., Cary, NC, USA) was used for all data collection and statistical analyses.
WC (cm) SBP (mmHg) DBP (mmHg) FBG (mg/dl) TG (mg/dl) HDL-C (mg/dl) Average no. of retained metabolic risk factors
87.9 ± 7.8 131.6 ± 15.5 81.7 ± 10.8 107.7 ± 25.9 188.4 ± 94.7 44.0 ± 12.6 3.6 ± 0.7
After 86.6 126.8 79.1 103.5 161.5 46.0 2.9
± 7.7 ± 14.0 ± 9.7 ± 22.0 ± 84.9 ± 12.4 ± 1.3
Difference P-value 1.26 4.85 2.58 4.21 26.89 þ2.02 0.74
<0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
WC: waist circumference; SBP: systolic blood pressure; DBP: diastolic blood pressure; FBG: fasting blood glucose; TG: triglyceride; HDL-C: high-density lipoprotein cholesterol.
Results Baseline characteristics
Effects of the lifestyle intervention
Among the 38,424 subjects participating in the intervention program and receiving follow-up examination after 12 months, 14,918 (38.8%) had MS. Of the 196,470 Seoul citizens aged 30 years and older with national health examination data and not participating in the intervention program, 50,283 (25.6%) had MS. From these non-participants, 14,918 for the control group were randomly extracted matched for age and sex to the intervention group. The clinical and laboratory characteristics of these 29,836 subjects are described in Table 1.
After 1 year of intervention, the individuals in the intervention group showed statistically significant improvements in all five risk factors, and the average number of retained risk factors decreased (Table 2.). The occurrence of hypertension was 555 (6.07%) and 751 (8.33%) and the occurrence of dyslipidemia was 321 (2.59%) and 373 (2.72%) in the intervention group and the control group, respectively. The occurrence of DM and AMI was significantly less in the intervention group than in the control group: 324 (2.55%) and 488 (3.89%) for DM and 13 (0.09%) and 26 (0.17%) for AMI, respectively (Table 3). In a similar analysis of 23,506 participants without MS and 23,506 randomly extracted age- and sex-matched non-participants without MS, the occurrence of DM and AMI was two to six times lower in those without MS than in those with MS: 140 (0.62%) and 149 (0.66%) for DM and 13 (0.06%) and 14 (0.06%) for AMI, respectively. In multivariate logistic regression analysis for the factors that were significant in the univariate analysis or affected the occurrence of DM, lifestyle intervention showed a preventive effect on the occurrence of DM with statistical significance with an adjusted odds ratio (OR) for intervention of 0.752 (95% confidence interval [CI]: 0.644e0.879). The analysis for AMI also showed a preventive effect with an adjusted OR of 0.499 (95% CI: 0.251e0.992) (Table 4). In multivariate logistic regression analysis for hypertension and dyslipidemia, lifestyle intervention did not show a preventive effect on the occurrence of disease with statistical significance.
Table 1 e Clinical and laboratory baseline characteristics of the subjects. Characteristics
Age (years) Men (%) Height (cm) Weight (kg) BMI (kg/m2) Non-smoking (%) Non-consumption of alcohol (%) Diagnosis history (%) Hypertension Diabetes mellitus Dyslipidemia WC (cm) SBP (mmHg) DBP (mmHg) FBG (mg/dl) TG (mg/dl) HDL-C (mg/dl) Average no. of retained metabolic risk factors
Intervention group (n ¼ 14,918)
Control group (n ¼ 14,918)
58.0 ± 9.1 37.6 160.6 ± 8.6 66.3 ± 10.9 25.6 ± 3.1 73.7 47.5
58.2 ± 9.2 37.6 160.2 ± 8.8 67.2 ± 11.2 26.1 ± 3.2 68.9 62.3
40.0 13.5 29.2 87.9 ± 7.9 131.6 ± 15.5 81.7 ± 10.8 107.7 ± 25.9 187.8 ± 94.3 43.8 ± 12.6 3.6 ± 0.7
44.3 17.8 14.7 86.9 ± 8.2 132.0 ± 14.5 81.0 ± 10.1 112.0 ± 30.6 187.6 ± 93.8 48.7 ± 11.7 3.5 ± 0.7
BMI: body mass index; WC: waist circumference; SBP: systolic blood pressure; DBP: diastolic blood pressure; FBG: fasting blood glucose; TG: triglyceride; HDL-C: high-density lipoprotein cholesterol.
Discussion There have been many lifestyle intervention programs for MS or IGT in several communities. For the effect of these programs, previous studies evaluated the reduced number of metabolic factors, the decreased rate of MS, and the changes
Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
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Table 3 e New occurrence of diseases according to participation. Metabolic syndrome (n ¼ 29,836)
Disease
P-value
Intervention group (n ¼ 14,918)
Control group (n ¼ 14,918)
New occurrence/non-patients (%)
New occurrence/non-patients (%)
555/ 9139 (6.1) 324/12,729 (2.6) 321/12,372 (2.6) 13/14,882 (0.1)
751/ 9011 (8.3) 488/12,537 (3.9) 373/13,696 (2.7) 26/14,881 (0.2)
Hypertension DM Dyslipidemia AMI
<0.001 <0.001 0.519 0.037
OR (95% CI)
1.41 1.55 1.05 2.00
(1.26e1.56) (1.34e1.79) (0.90e1.22) (1.03e3.90)
OR: odds ratio; CI: confidence interval; DM: diabetes mellitus; AMI: acute myocardial infarction.
in such indicators related to cardiovascular complications before and after the intervention. In this study, we found that the metabolic factors were improved and the average number of retained risk factors decreased. Although IGT is one of the components of the MS, and lifestyle intervention affects the common effect on the subjects with MS or IGT, to evaluate the preventive effects of lifestyle intervention in MS is more important in establishing appropriate healthcare policies. There are many studies about the associations between MS and hypertension, DM, and AMI, and the preventive effects of lifestyle intervention on the occurrence of DM in subjects with IGT have already been proven. However, few studies have assessed the occurrence of these diseases according to lifestyle intervention in MS without each disease. In particular, a study reported that lifestyle intervention improved CVD risk factor status, but no differences in CVD events were noted in IGT.11 Therefore, it is important to assess the occurrence of AMI, one of the most serious cardiovascular events, with respect to lifestyle intervention. In this study, the claims data from the National Health Insurance Service were used to identify the occurrence of hypertension, DM, dyslipidemia, and AMI. South Korea has a single health insurance system, and health check-ups target the entire population every 1 or 2 years. Moreover, Koreans may visit clinics frequently owing to the lower threshold for primary health care institutions and can easily receive medical consultations or examinations. Therefore, considering the new occurrence of non-communicable diseases such as hypertension, DM, and dyslipidemia as one visit can result in overestimation. Therefore, occurrence was defined as a subject with one inpatient admission or more than three outpatient visits for these diseases.16 In our study, considering a case as a claim with any admission or outpatient visit, the occurrence of hypertension was 838 (9.17%) and 1239 (13.75%), the occurrence of DM was 649 (5.1%) and 936 (7.47%), and the occurrence of dyslipidemia was 946 (7.65%) and 1296 (9.46%) in
the intervention group and the control group, respectively, all with statistical significance. It is assumed for this reason that the occurrence of DM within 1 year after the intervention or the health examination was somewhat lower than that of other studies.9,10 Meanwhile, the occurrence of AMI was defined as a subject with a claim with admission or outpatient visit, considering the severity of the disease, as the accuracy for diagnosing AMI in Korean National Medical Health Insurance claims data is over 70%, and reliability is fair to good.17 However, even if the occurrence was defined as the subject with more than one inpatient admission, considering the limitation of the claims data, AMI occurred significantly less in the intervention group than in the control group (P ¼ 0.033). In multivariate logistic regression analysis for the factors that were significant in the univariate analysis or affected the occurrence of DM,18 such as participation in a lifestyle intervention program, sex, age, FBG, WC, and average number of retained metabolic risk factors, a preventive effect on the occurrence of DM was shown. A more active and tailored intervention is needed for subjects with higher FBG levels and WC at the time of MS diagnosis to affect the occurrence of DM. In multivariate logistic regression analysis for the factors affecting the occurrence of AMI,19 such as participation in a lifestyle intervention program, sex, diagnosis or history of hypertension and DM, and smoking, a preventive effect on the occurrence of AMI was also shown. In this study, we selected 50,283 subjects with MS among 196,470 non-participants for controls. The mean of age of these subjects with MS was 56.7 years, and the proportion of men was 56.6%. Therefore, we randomly extracted the same number as individual in intervention group with matching age and sex. For these 50,283 subjects with MS, the occurrence of DM and AMI was 1518/42,541 (3.57%) and 80/50,151 (0.16%), respectively. As limitations of the study, the participants enrolled in the metropolitan lifestyle intervention program were not a random sample; so, the preventive effects of lifestyle
Table 4 e Multivariate logistic regression analysis in new occurrence of DM and AMI. Disease DM AMI
Intervention No Yes No Yes
No. of new occurrences (%) 488 324 26 13
(3.9) (2.6) (0.2) (0.1)
Crude OR 1.00 0.65 1.00 0.50
95% CI
P-value
0.56e0.74
<0.001
0.26e0.97
0.041
Adjusted OR 1.00 0.75a 1.00 0.50b
95% CI
P-value
0.64e0.88
<0.001
0.25e0.99
0.048
OR: odds ratio; CI: confidence interval; DM: diabetes mellitus; AMI: acute myocardial infarction. a Adjusted for participation, sex, age, fasting blood glucose, waist circumference, and average number of retained metabolic risk factors in DM. b Adjusted for participation, sex, age, diagnosis history of hypertension and DM, smoking, and AMI.
Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012
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intervention may be overestimated. However, it is difficult to determine whether the intervention after random sampling while operating a public education program as it has already been demonstrated that the lifestyle intervention improve the metabolic parameters. We confirmed that the average number of retained risk factors decreased after lifestyle intervention in the intervention group, but we did not observe the laboratory characteristics of the control group after 1 year. This is a limitation of our study, but because other studies showed no change or a tendency to become worse in the control group, we supposed the control group would show similar results.8,12 Another important limitation is that study follow-up for the occurrence of the diseases was limited to 1 year despite an interim report. Continuous follow-up is needed to evaluate long-term effects. In addition, because the national health examination data do not have the entry for the educational and economic levels, there is a limit to grasp socio-economic status. Despite its limitations, this was a large-scale research study with controls to assess the preventive effects of lifestyle intervention on the occurrence of DM and AMI in MS. Moreover, the effect may be expected to be greater considering the healthy volunteer effect20 in control group with health examination data, and this result will help in establishing community health programs.
Author statements
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6.
7.
8.
9.
10.
11.
12.
Ethical approval The study protocol was approved by the institutional review board of Korea University (1040548-KU-IRB-13-118-A-1).
13.
Funding This study was supported by a grant from the National R&D Program for Cancer Control, Ministry of Health and Welfare, Korea (grant no. 1320310).
14.
Competing interests 15.
The authors have not declared any conflicts of interest.
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Please cite this article in press as: Kim D, et al., The preventive effects of lifestyle intervention on the occurrence of diabetes mellitus and acute myocardial infarction in metabolic syndrome, Public Health (2016), http://dx.doi.org/10.1016/j.puhe.2016.06.012