| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Hypertension. 2006;47:162.)
© 2006 American Heart Association, Inc.
Original Articles |
From the Weill Medical College (G.d.S., R.B.D., M.J.R.), Cornell University, New York, NY; Federico II University Hospital (G.d.S., M.C.), Naples, Italy; Missouri Breaks Industries Research (L.G.B., T.K.W.), Timber Lake, SD; Center for American Indian Health Research (E.T.L.), University of Oklahoma, Oklahoma City, Okla; and Medstar Research Institute (B.V.H.), Washington, DC.
Correspondence to Giovanni de Simone, Division of Cardiology, The New York Presbyterian Hospital-Weill Medical College of Cornell University, 525 East 68th St, New York, NY 10021. E-mail simogi{at}unina.it
| Abstract |
|---|
|
|
|---|
Key Words: metabolism insulin resistance lipids lipoproteins population risk factors
| Introduction |
|---|
|
|
|---|
| Methods |
|---|
|
|
|---|
120 mm Hg, diastolic pressure
80 mm Hg, ongoing antihypertensive treatment,4,5,17 and prevalent and/or incident nonfatal cardiovascular disease over 8-year follow-up through the third SHS examination. Prevalent and incident cardiovascular disease were adjudicated as reported previously in detail15,18 by physician members of the SHS Mortality and Morbidity Committees to confirm causes of death and to establish specific cardiovascular disease diagnoses. Diabetic and obese participants were included; participants with fasting triglyceride levels >750 mg/dL were excluded. Thus, 967 normotensive participants (69.5% women) with a mean age of 54±7 years were finally considered in the present analysis.
Laboratory Tests and Classification of Participants
Fasting plasma glucose and lipid profiles were measured by standard methods.14 Diabetes and impaired glucose tolerance were diagnosed by 1997 American Diabetes Association recommendations.19 Obesity was classified based on the 1998 National Institutes of Health guidelines,20 and the same guidelines were used to define sex-specific central fat distribution.
Statistical Analysis
Data were analyzed using SPSS 12.0 software (SPSS). Data are expressed as mean±SD. Indicator variables were included for the 3 field centers: Arizona, South/North Dakota, and Oklahoma. Incident hypertension was defined as BP
140 and/or 90 mm Hg or ongoing antihypertensive treatment at both second and third exams after 46±9 and 92±13 months from baseline examination, respectively. Descriptive statistics were obtained by 1-factor ANOVA or
2 distribution. When needed, the REGW-F post hoc test was also carried out. Predictors of arterial hypertension were evaluated using binary multiple logistic regression and a backward stepwise procedure, with P-to-enter <0.05 and P-to-remove >0.1, which are the default values of the SPSS statistical package. Participants with impaired glucose tolerance or diabetes were pooled and analyzed separately from subjects with normal glucose tolerance based on considerations developed in the exploratory ANOVA. Wald statistics were used to estimate the strength of the estimated relative risk (expressed as the exponential of the b coefficient). Variables considered in logistic models were grouped in 2 subsets: the first one was used to predict incident hypertension at the second examination and included baseline age, gender, field center, body mass index (BMI), waist girth, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, systolic and diastolic BP, plasma glucose, and diabetes status. The second set of variables was added to the first set for prediction of incident hypertension at the third examination and comprised prevalent hypertension and diabetes at the second examination and the percentage changes of systolic and diastolic BP; body weight; fasting glucose; total, HDL, and LDL cholesterol; triglycerides; and waist girth between the first and second examination.
| Results |
|---|
|
|
|---|
Table 1 shows baseline characteristics of participants remaining normotensive over the 8 years of follow-up compared with the separate groups that developed arterial hypertension at the second or third examination. Analysis for trend showed that, at baseline, subjects developing arterial hypertension were more obese and had more central fat distribution, higher BP, high plasma glucose, and greater prevalence of diabetes (all P<0.001). Post hoc comparison revealed no difference between subjects with identified hypertension at 4 or 8 years.
|
Characteristics of this cohort were also examined on the basis of glucose metabolism. Table 2 shows that, at baseline, participants with either impaired glucose tolerance or diabetes exhibited a greater prevalence of central obesity, with somewhat lower plasma cholesterol, as well as HDL and LDL cholesterol, and no difference in baseline BP. The prevalence of women was also greater in the presence of impaired glucose metabolism. Post hoc comparison, however, did not demonstrate any statistically appreciable difference between subjects with impaired glucose tolerance or diabetes.
|
Based on the above exploratory analysis suggesting that the population subgroups with impaired glucose tolerance or diabetes could be considered a quite homogeneous cluster for the purpose of the present analysis, the study population was divided into 2 groups, normal glucose tolerance and impaired glucose tolerance/diabetes, and the following analyses were performed separately in these 2 subgroups.
Predictors of Hypertension After 4 Years
After 4 years, even with initially optimal levels of BP, development of arterial hypertension (n=113) was associated with higher baseline systolic pressure (b=0.077/mm Hg; P<0.004) and BMI (b=0.059/kgxm2; P<0.05) in normal glucose tolerance and with higher baseline systolic BP (b=0.048/mm Hg; P<0.03) and diabetes status (b=0.68; P=0.05) in impaired glucose tolerance/diabetes without any other considered variable (listed in the Statistical Analysis section) remaining in the final predictive models.
Predictors of Hypertension After 8 Years
In participants with normal baseline glucose tolerance, as well as stringently normal BP, higher baseline waist circumference and systolic BP, evidence of diabetes at the second examination, increase in systolic BP and waist circumference, and decrease in HDL cholesterol from baseline to the second examination predicted 8-year arterial hypertension independent of the development of definite hypertension at the second examination (4 years) (Table 3). Of note, the 4-year decrease in HDL cholesterol was as strong an independent predictor of 8-year incident hypertension as the baseline level of systolic BP, as shown by the respective Wald statistics.
|
In contrast, a slightly different profile of predictors of 8-year incident arterial hypertension was observed in participants with impaired glucose tolerance or diabetes at baseline (Table 4). The most potent independent predictor of incident hypertension was the presence of diabetes at the time of the second examination followed by the increase in systolic BP and in LDL cholesterol over time, with a small additional contribution from the baseline level of systolic BP.
|
| Discussion |
|---|
|
|
|---|
In contrast with the previous studies, the present analysis has been carried out considering only participants with strictly defined normal BP by Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure criteria.5 The strategy was decided to verify whether the ability of metabolic risk factors to predict incident arterial hypertension was predominant in the context of optimal BP but relatively high prevalence of other cardiovascular risk factors. We found, in fact, a substantial impact of metabolic profile in predicting arterial hypertension.
The scenario emerging from our findings is that, in the presence of initial relatively low BP (Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure normal), the metabolic profile and its worsening over time are strong predictors of development of arterial hypertension. These findings, therefore, suggest that when BP is low, atherogenic risk factors play major roles in stiffening arteries and increasing peripheral resistance. In the presence of normal glucose metabolism, the combined effect of initial central fat distribution, increasing abdominal adiposity, and worsening of lipid profile was even greater than initial levels of systolic BP and its increase over time in predicting incident 8-year arterial hypertension. Of interest, in participants with abnormal initial glucose metabolism, evidence of diabetes at the second examination was the most potent predictor and, together with worsening in the lipid profile, explains most incident hypertension. These metabolic effects were also independent of the presence of hypertension at 4-year examination, consistent with the evidence of rapid stiffening of the arterial system exposed to diabetes.25
Another interesting point emerging from our findings concerns obesity. Although obesity is prevalent in the SHS population, once lipid profile and plasma glucose were considered, body weight had less effect than expected from reports from other populations, whereas central fat distribution appears to be important only when glucose tolerance is normal (see Table 3). This different effect of central fat distribution might be attributable to the higher variability shown among participants with normal plasma glucose than among those with abnormal glucose metabolism, in whom central adiposity was almost always present. A number of investigators attribute the negative cardiovascular consequences of obesity to its association with a cluster of risk factors, rather than to its being a primary causal cardiovascular risk factor.26 Of note, obesity is reported to be a direct causal risk factor for increasing the metabolic predictors11 that we have identified as risk factors for incident arterial hypertension in the present study. In addition, there is previous evidence that the risk of obesity is substantially related to the accumulation of intraabdominal fat.27,28 Overall, our results suggest that impaired glucose metabolism, abnormal lipid profile, and high-normal BP levels largely mediate the effect of central obesity in predicting incident hypertension. However, our findings also suggest that consideration of metabolic syndrome as a clinical entity might help identify individuals at risk for the development of arterial hypertension. Efforts to prevent arterial hypertension might be successful with interventions to improve body build and metabolic profile, targeted to individuals with optimal BP.
In addition to the factors highlighted in our analysis, smoking habit has also been reported to be another potential predictor of hypertension in different ethnic groups,29 possibly because of increased arterial stiffness. Because our analyses were conducted in a population of American Indians, their generalizability needs to be verified in other populations, especially because algorithms for risk prediction are substantially affected by prevalence and distribution of individual risk factors.30 Moreover, arterial hypertension in this population is mainly systolic,31 and, therefore, additional study is needed to examine predictors of diastolic hypertension. It should also be considered, however, that data from this population have been repeatedly shown to be valuable in understanding metabolic phenomena associated with obesity, insulin resistance, and diabetes relevant to other populations in which these disorders are becoming epidemic.
| Conclusions |
|---|
|
|
|---|
Perspectives
There are implications of these findings for primary cardiovascular prevention that should be tested in prospective studies. Hypertension is the leading risk factor for cardiovascular mortality and morbidity, and much effort is devoted to reducing BP with high financial and social costs and a relative ineffectiveness of interventions, because only a relatively small proportion of the hypertensive population is optimally controlled.32,33 Interventions to prevent this most important risk factor might be very effective in helping to reduce cardiovascular risk and direct and indirect costs related to arterial hypertension. Although the evidence that BP levels predict future high BP is neither new nor surprising, it is clear that individual detection of optimal values of BP does not allow the prediction of development of hypertension. Thus, consideration of the additional factors highlighted in this study might be crucial in setting programs focused on primary prevention of arterial hypertension.
| Acknowledgments |
|---|
| Footnotes |
|---|
Received October 23, 2005; first decision November 9, 2005; accepted November 21, 2005.
| References |
|---|
|
|
|---|
2. Vasan RS, Beiser A, Seshadri S, Larson MG, Kannel WB, DAgostino RB, Levy D. Residual lifetime risk for developing hypertension in middle-aged women and men: The Framingham Heart Study. JAMA. 2002; 287: 10031010.
3. Port S, Demer L, Jennrich R, Walter D, Garfinkel A. Systolic blood pressure and mortality. Lancet. 2000; 355: 175180.[CrossRef][Medline] [Order article via Infotrieve]
4. Practice Guidelines For Primary Care Physicians: 2003 ESH/ESC Hypertension Guidelines. J Hypertens. 2003; 21: 17791786.[CrossRef][Medline] [Order article via Infotrieve]
5. Lenfant C, Chobanian AV, Jones DW, Roccella EJ. Seventh report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7): resetting the hypertension sails. Hypertension. 2003; 41: 11781179.
6. Kannel WB, Vasan RS, Levy D. Is the relation of systolic blood pressure to risk of cardiovascular disease continuous and graded, or are there critical values? Hypertension. 2003; 42: 453456.
7. Wilsgaard T, Schirmer H, Arnesen E. Impact of body weight on blood pressure with a focus on sex differences: the Tromso Study, 19861995. Arch Intern Med. 2000; 160: 28472853.
8. Klein S, Burke LE, Bray GA, Blair S, Allison DB, Pi-Sunyer X, Hong Y, Eckel RH. Clinical implications of obesity with specific focus on cardiovascular disease: a statement for professionals from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism: Endorsed by the American College of Cardiology Foundation. Circulation. 2004; 110: 29522967.
9. Davy KP, Hall JE. Obesity and hypertension: two epidemics or one? Am J Physiol Regul Integr Comp Physiol. 2004; 286: R803R813.
10. Diez Roux AV, Chambless L, Merkin SS, Arnett D, Eigenbrodt M, Nieto FJ, Szklo M, Sorlie P. Socioeconomic disadvantage and change in blood pressure associated with aging. Circulation. 2002; 106: 703710.
11. 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) final report. Circulation. 2002; 106: 31433421.
12. Lee ET, Fabsitz R, Cowan LD, Le NA, Oopik AJ, Cucchiara AJ, Savage PJ, Howard BV. The Strong Heart Study A study of cardiovascular disease in American Indians: Design and methods. Am J Epidemiol. 1990; 136: 11411155.
13. Howard BV, Lee ET, Yeh JL, Go O, Fabsitz RR, Devereux RB, Welty TK. Hypertension in adult American Indians. The Strong Heart Study. Hypertension. 1996; 28: 256264.
14. Welty TK, Lee ET, Yeh J, Cowan LD, Go O, Fabsitz RR, Le NA, Oopik AJ, Robbins DC, Howard BV. Cardiovascular disease risk factors among American Indians. The Strong Heart Study. Am J Epidemiol. 1995; 142: 269287.
15. Lee ET, Cowan LD, Welty TK, Sievers M, Howard WJ, Oopik A, Wang W, Yeh J, Devereux RB, Rhoades ER, Fabsitz RR, Go O, Howard BV. All-cause mortality and cardiovascular disease mortality in three American Indian populations, aged 4574 years, 19841988. The Strong Heart Study. Am J Epidemiol. 1998; 147: 9951008.
16. Devereux RB, Roman MJ, Paranicas M, OGrady MJ, Lee ET, Welty TK, Fabsitz RR, Robbins D, Rhoades ER, Howard BV. Impact of diabetes on cardiac structure and function: the strong heart study. Circulation. 2000; 101: 22712276.
17. Joint National Committee on Detection Evaluation and Treatment of High Blood Pressure. The Sixth Report of the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure. Arch Intern Med. 1997; 157: 24132446.
18. Howard BV, Lee ET, Cowan LD, Devereux RB, Galloway JM, Go OT, Howard WJ, Rhoades ER, Robbins DC, Sievers ML, Welty TK. Rising tide of cardiovascular disease in American Indians. The Strong Heart Study. Circulation. 1999; 99: 23892395.
19. American Diabetes Association. Clinical practice recommendations 1997. Diabetes Care. 1997; 20: S1S70.[Medline] [Order article via Infotrieve]
20. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults-The Evidence Report. National Institutes of Health. Obes Res. 1998; 6: 51S209S.[Medline] [Order article via Infotrieve]
21. Vasan RS, Larson MG, Leip EP, Kannel WB, Levy D. Assessment of frequency of progression to hypertension in non-hypertensive participants in the Framingham Heart Study: a cohort study. Lancet. 2001; 358: 16821686.[CrossRef][Medline] [Order article via Infotrieve]
22. Bakx JC, van den Hoogen HJ, van den Bosch WJ, van Schayck CP, van Ree JW, Thien T, van Weel C. Development of blood pressure and the incidence of hypertension in men and women over an 18-year period: results of the Nijmegen Cohort Study. J Clin Epidemiol. 1999; 52: 531538.[CrossRef][Medline] [Order article via Infotrieve]
23. Dyer AR, Liu K, Walsh M, Kiefe C, Jacobs DR, Jr, Bild DE. Ten-year incidence of elevated blood pressure and its predictors: the CARDIA study. Coronary Artery Risk Development in (Young) Adults. J Hum Hypertens. 1999; 13: 1321.[CrossRef][Medline] [Order article via Infotrieve]
24. Borghi C, Veronesi M, Bacchelli S, Esposti DD, Cosentino E, Ambrosioni E. Serum cholesterol levels, blood pressure response to stress and incidence of stable hypertension in young subjects with high normal blood pressure. J Hypertens. 2004; 22: 265272.[CrossRef][Medline] [Order article via Infotrieve]
25. Dart AM, Kingwell BA. Pulse pressure-a review of mechanisms and clinical relevance. J Am Coll Cardiol. 2001; 37: 975984.
26. Barrett-Connor EL. Obesity, atherosclerosis, and coronary artery disease. Ann Intern Med. 1985; 103: 10101019.[Medline] [Order article via Infotrieve]
27. Scaglione R, Ganguzza A, Corrao S, Parrinello G, Merlino G, Dichiara MA, Arnone S, DAubert MD, Licata G. Central obesity and hypertension: pathophysiologic role of renal haemodynamics and function. Int J Obes Relat Metab Disord. 1995; 19: 403409.[Medline] [Order article via Infotrieve]
28. De Michele M, Panico S, Iannuzzi A, Celentano E, Ciardullo AV, Galasso R, Sacchetti L, Zarrilli F, Bond MG, Rubba P. Association of obesity and central fat distribution with carotid artery wall thickening in middle-aged women. Stroke. 2002; 33: 29232928.
29. Mundal R, Kjeldsen SE, Sandvik L, Erikssen G, Thaulow E, Erikssen J. Predictors of 7-year changes in exercise blood pressure: effects of smoking, physical fitness and pulmonary function. J Hypertens. 1997; 15: 245249.[CrossRef][Medline] [Order article via Infotrieve]
30. Giampaoli S, Palmieri L, Mattiello A, Panico S. Definition of high risk individuals to optimise strategies for primary prevention of cardiovascular diseases. Nutr Metab Cardiovasc Dis. 2005; 15: 7985.[CrossRef][Medline] [Order article via Infotrieve]
31. de Simone G, Devereux RB, Chinali M, Best LG, Lee ET, Welty TK. Association of blood pressure with blood viscosity in American Indians. The Strong Heart Study. Hypertension. 2005; 45: 625630.
32. Mancia G, Sega R, Milesi C, Cesana G, Zanchetti A. Blood-pressure control in the hypertensive population. Lancet. 1997; 349: 454457.[CrossRef][Medline] [Order article via Infotrieve]
33. Appel LJ, Champagne CM, Harsha DW, Cooper LS, Obarzanek E, Elmer PJ, Stevens VJ, Vollmer WM, Lin PH, Svetkey LP, Stedman SW, Young DR. Effects of comprehensive lifestyle modification on blood pressure control: main results of the PREMIER clinical trial. JAMA. 2003; 289: 20832093.
This article has been cited by other articles:
![]() |
M. De Marco, G. de Simone, M. J. Roman, M. Chinali, E. T. Lee, M. Russell, B. V. Howard, and R. B. Devereux Cardiovascular and Metabolic Predictors of Progression of Prehypertension Into Hypertension: The Strong Heart Study Hypertension, November 1, 2009; 54(5): 974 - 980. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. H. de Boer, B. Kestenbaum, T. C. Rue, M. W. Steffes, P. A. Cleary, M. E. Molitch, J. M. Lachin, N. S. Weiss, J. D. Brunzell, and for the Diabetes Control and Complications Trial ( Insulin Therapy, Hyperglycemia, and Hypertension in Type 1 Diabetes Mellitus Arch Intern Med, September 22, 2008; 168(17): 1867 - 1873. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Williams The Year in Hypertension J. Am. Coll. Cardiol., October 17, 2006; 48(8): 1698 - 1711. [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Hypertension Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 2006 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |