Large Cohort Data Based Group or Community Disease Prevention Design Strategy: Strong Heart Study.

BACKGROUND AND OBJECTIVE: A multitude of large cohort studies have data on incidence rates and predictors of various chronic diseases. However, approaches for utilization of these costly collected data and translation of these valuable results to inform and guide clinical disease prevention practice are not well developed. In this paper we proposed a novel conceptual group/community disease prevention design strategy based on large cohort study data. METHODS AND RESULTS: The data from participants (n = 3516; 2056 women) aged 45 to 74 years and the diabetes risk prediction model from Strong Heart Study were used. The Strong Heart Study is a population-based cohort study of cardiovascular disease and its risk factors in American Indians. A conceptual group/community disease prevention design strategy based on large cohort data was initiated. The application of the proposed strategy for group diabetes prevention was illustrated. DISCUSSION: The strategy may provide reasonable solutions to the prevention design issues. These issues include complex associations of a disease with its combined and correlated risk factors, individual differences, choosing intervention risk factors and setting their appropriate, attainable, gradual and adaptive goal levels for different subgroups, and assessing effectiveness of the prevention program. CONCLUSIONS: The strategy and methods shown in the illustration example can be analogously adopted and applied for other diseases preventions. The proposed strategy for a target group/community in a population provides a way to translate and apply epidemiological study results to clinical disease prevention practice.

Large Cohort Data Based Cost-Effective Disease Prevention Design Strategy: Strong Heart Study.

BACKGROUND AND OBJECTIVE: A multitude of large cohort studies have collected data on incidence and covariates/risk factors of various chronic diseases. However, approaches for utilization of these large data and translation of the valuable results to inform and guide clinical disease prevention practice are not well developed. In this paper, we proposed, based on large cohort study data, a novel conceptual cost-effective disease prevention design strategy for a target group when it is not affordable to include everyone in the target group for intervention. METHODS AND RESULTS: Data from American Indian participants (n = 3516; 2056 women) aged 45 - 74 years in the Strong Heart Study, the diabetes risk prediction model from the study, a utility function, and regression models were used. A conceptual cost-effective disease prevention design strategy based on large cohort data was initiated. The application of the proposed strategy for diabetes prevention was illustrated. DISCUSSION: The strategy may provide reasonable solutions to address cost-effective prevention design issues. These issues include complex associations of a disease with its significant risk factors, cost-effectively selecting individuals at high risk of developing disease to undergo intervention, individual differences in health conditions, choosing intervention risk factors and setting their appropriate, attainable, gradual and adaptive goal levels for different subgroups, and assessing effectiveness of the prevention program. CONCLUSIONS: The strategy and methods shown in the illustrative example can also be analogously adopted and applied to other diseases preventions. The proposed strategy provides a way to translate and apply epidemiological study results to clinical disease prevention practice.

A Self-assessment Tool for Screening Young Adults at Risk of Type 2 Diabetes Using Strong Heart Family Study Data.

PURPOSE: The purpose of this study is to characterize risk factors associated with type 2 diabetes in young adults aged 18 to 29 years to develop a noninvasive risk assessment tool for use with younger American populations. METHODS: The self-assessment tool was developed with the Strong Heart Family Study data. A total of 590 young American Indian adults (242 men) who had normoglycemia and were not receiving diabetes treatment were included. Risk factors recommended by the American Diabetes Association were used to assess diabetes risk in these young adults. A logistic regression model was developed to calculate the predicted probability. The area under the receiver operating characteristic curve was used to evaluate the model. RESULTS: The final model showed that parental history of diabetes, obesity level, alcohol consumption, and high fasting glucose, even within normal range, were significantly associated with onset of prediabetes/diabetes in 5 years. The area under the receiver operating characteristic curve value was 0.68 with original and validated data, indicating that the risk assessment tool had reasonably good discrimination ability. CONCLUSIONS: This new noninvasive screening tool, based on data from American Indian young adults, has potential to screen young adults' early-onset diabetes risk. Future studies are warranted to test this risk assessment tool in other racial/ethnic young adults.

Prevalence of diabetes and impaired fasting glucose in Chinese adults, China National Nutrition and Health Survey, 2002.

INTRODUCTION: As a result of rapid economic development in China, the lifestyles and dietary habits of its people have been changing, and the rates of obesity, diabetes, and other chronic conditions have increased substantially. We report the prevalence of type 2 diabetes and impaired fasting glucose (IFG) and the association between diabetes and overweight and obesity in Chinese adults. We also compare the results with those from the US National Health and Nutrition Examination Survey, 1999-2002. METHODS: Data were from adults aged 20 years or older who participated in the China National Nutrition and Health Survey, 2002 (n = 47,729). Diabetes and IFG were defined by the American Diabetes Association 2009 criteria. We assessed the prevalence of diabetes, IFG, and overweight and obesity by sex, age, region of residence, and ethnicity. RESULTS: The prevalence of diabetes and IFG in Chinese adults was 2.7% and 4.9%, respectively. The prevalence of diabetes increased with age and body mass index. Men and women had a similar prevalence of diabetes, but men had a significantly higher prevalence of IFG. The prevalence of diabetes among Chinese who lived in urban areas was 2 to 3 times higher than the prevalence among those who lived in rural areas (3.9% for urban areas and 6.1% for large cities vs 1.9% for rural areas), and the prevalence of IFG was 1.5 to 2 times higher (6.1% and 8.1% vs 4.2%, respectively). The prevalence of diabetes among Chinese women and young (20-39 y) and middle-aged (40-59 y) adults who lived in large cities was similar to the prevalence of diabetes in the US population. CONCLUSION: The prevalence of diabetes and IFG was much higher in urban than rural areas, particularly in the large cities of China. Prevention must be emphasized among adults to reduce the future social and economic burden of diabetes in China.

Cost-effectiveness of lower targets for blood pressure and low-density lipoprotein cholesterol in diabetes: the Stop Atherosclerosis in Native Diabetics Study (SANDS) .

BACKGROUND: The Stop Atherosclerosis in Native Diabetics Study (SANDS) reported cardiovascular benefit of aggressive versus standard treatment targets for both low-density lipoprotein cholesterol (LDL-C) and blood pressure (BP) in diabetic individuals. OBJECTIVE: In this analysis, we examined within trial cost-effectiveness of aggressive targets of LDL-C ≤70 mg/dL and systolic BP ≤115 mmHg versus standard targets of LDL-C ≤100 mg/dL and systolic BP ≤130 mmHg. DESIGN: Randomized, open label blinded-to-endpoint 3-year trial. DATA SOURCES: SANDS clinical trial database, Quality of Wellbeing survey, Centers for Medicare and Medicaid Services, Wholesale Drug Prices. TARGET POPULATION: American Indians ≥ age 40 years with type 2 diabetes and no previous cardiovascular events. TIME HORIZON: April 2003 to July 2007. PERSPECTIVE: Health payer. INTERVENTIONS: Participants were randomized to aggressive versus standard groups with treatment algorithms defined for both. OUTCOME MEASURES: Incremental cost-effectiveness. RESULTS OF BASE-CASE ANALYSIS: Compared with the standard group, the aggressive group had slightly lower costs of medical services (-$116) but a 54% greater cost for BP medication ($1,242) and a 116% greater cost for lipid-lowering medication ($2,863), resulting in an increased cost of $3,988 over 3 years. Those in the aggressively treated group gained 0.0480 quality-adjusted life-years (QALY) over the standard group. When a 3% discount rate for costs and outcomes was used, the resulting cost per QALY was $82,589. RESULTS OF SENSITIVITY ANALYSIS: The use of a 25%, 50%, and 75% reduction in drug costs resulted in a cost per QALY of $61,329, $40,070, and $18,810, respectively. LIMITATIONS: This study was limited by use of a single ethnic group and by its 3-year duration. CONCLUSIONS: Within this 3-year study, treatment to lower BP and LDL-C below standard targets was not cost-effective because of the cost of the additional medications required to meet the lower targets. With the anticipated availability of generic versions of the BP and lipid-lowering drugs used in SANDS, the cost-effectiveness of this intervention should improve. Published by Elsevier Inc on behalf of the National Lipid Association.

Social- and behavioral-specific genetic effects on blood pressure traits: the Strong Heart Family Study.

BACKGROUND: Population studies have demonstrated an important role of social, behavioral, and environmental factors in blood pressure (BP) levels. Accounting for the genetic interaction of these factors may help to identify common BP susceptibility alleles. METHODS AND RESULTS: We studied the interaction of additive genetic effects and behavioral (physical activity, smoking, alcohol use) and socioeconomic (education) factors on BP in approximately 3600 American Indian participants of the Strong Heart Family Study, using variance component models. The mean and SD of resting systolic and diastolic BPs were 123 + or - 17 and 76 + or - 11 mm Hg, respectively. We detected evidence for distinct genetic effects on diastolic BP among ever smokers compared with never smokers (P = 0.01). For alcohol intake, we observed significant genotype-by-environment interactions on diastolic (rhog = 0.10, P = 0.0003) and on systolic BPs (rhog = 0.59, P = 0.0008) among current drinkers compared with former or never drinkers. We also detected genotype-by-physical activity interactions on diastolic BP (rhog = 0.35, P = 0.0004). Finally, there was evidence for distinct genetic effects on diastolic BP among individuals with less than high school education compared with those with 12 or more years of education (rhog = 0.41, P = 0.02). CONCLUSIONS: Our findings suggest that behavioral and socioeconomic factors can modify the genetic effects on BP phenotypes. Accounting for context dependent factors may help us to better understand the complexities of the gene effects on BP and other complex phenotypes with high levels of genetic heterogeneity.

Prognostic implications of relations of left ventricular systolic dysfunction with body composition and myocardial energy expenditure: the Strong Heart Study.

OBJECTIVE: We sought to investigate prognostic implications of the relationships of estimated left ventricular (LV) myocardial energy expenditure (MEE) with LV systolic dysfunction, body composition, and inflammation in a population-based sample of adults without overt congestive heart failure. METHODS: Echocardiography was used to assess LV ejection fraction (EF) and MEE. Body composition was evaluated by bioelectric impedance. Dietary recall was used to assess 24-hour calorie intake. Participants in the Strong Heart Study without prior congestive heart failure and with all needed data available (n = 3087) were divided based on LV EF (>55%, 54%-45%, or <45%). RESULTS: Participants with EF less than 45% were older and they had lower body mass index, adipose mass, fat-free mass, and 24-hour calorie intake than participants with normal EF (>/=55%), and had greatest reductions of body mass index and physical activity in a time interval of 3.5 years, on average, elapsed between an initial clinical assessment and the evaluation at the time of the echocardiographic examination (P < .01). Lower EF was associated with male sex, hypertension, diabetes, coronary heart disease, and higher fibrinogen, C-reactive protein, and plasma creatinine levels (all P < .01). MEE was higher with lower EF (all P < .001). In Cox regression models, during approximately 8 years of observation, MEE comprised between 97 and 123 cal/min and MEE greater than 123 cal/min were associated with 2.5-fold and additional 3.3-fold higher rates of cardiac death, respectively, compared with MEE less than 97 cal/min, independently of EF, body composition, and other covariates. However, lower adipose mass predicted increased risk of cardiac death independent of MEE and EF. CONCLUSION: In a population-based sample of adults including ambulatory individuals with depressed LV systolic function but without overt congestive heart failure, depressed EF was associated independently with higher MEE, lower adipose mass, and higher fibrinogen. However, increased MEE and lower adipose mass predicted cardiac death independently of EF and other covariates.

Usefulness of quantitative assessment of electrocardiographic ST depression for predicting new-onset heart failure in American Indians (from the Strong Heart Study).

The qualitative electrocardiographic strain pattern of ST depression (STD) and T-wave inversion is strongly associated with coronary heart disease and left ventricular hypertrophy and is an independent predictor of new-onset heart failure in hypertensive participants. However, whether quantitative measures of STD in the lateral precordial leads predict new heart failure is unclear. Digital electrocardiograms were examined in 2,059 American-Indian participants in the second Strong Heart Study examination with no history of heart failure. The absolute magnitude of ST segment deviation was measured using computer to the nearest 5 microV in leads V(5) and V(6). During 5.7 +/-1.4 years of follow-up, heart failure developed in 77 participants (3.7%). Participants who developed heart failure had greater STD in leads V(5) or V(6) (-11 +/- 35 vs 12 +/- 27 microV; p <0.001) than those who did not. In univariate Cox analyses, STD was a significant predictor of new heart failure, with each 10-microV greater STD associated with a 31% greater risk of heart failure (hazard ratio [HR] 1.31, 95% confidence interval [CI] 1.24 to 1.39). Increasing STD grouped according to quartiles was strongly associated with the development of heart failure, with stepwise increasing risk of heart failure compared with the lowest quartile of STD for the second (HR 2.39, 95% CI 0.77 to 7.40), third (HR 3.01, 95% CI 1.00 to 9.08), and fourth quartiles of STD (HR 9.06, 95% CI 3.26 to 25.16). In Cox multivariate analyses controlling for age, gender, diabetes, coronary heart disease, albuminuria, and other baseline risk factors, STD remained a significant predictor of incident heart failure (HR 1.22, 95% CI 1.13 to 1.32 per 10-muV increment in STD; p <0.001). In conclusion, increasing STD in lateral precordial leads is strongly associated with increased risk of developing heart failure independent of other risk factors for new heart failure.

Tobacco use among American Indians in Oklahoma: an epidemiologic view.

OBJECTIVES: With the exception of national surveys that sample the entire U.S. population, little information exists on tobacco habits among American Indians. This study is a comparison of tobacco use findings in the 1990s among American Indians in Oklahoma, a state with a large and diverse American Indian population (39 tribes). METHODS: Data on current tobacco use are presented from two statewide surveys, the Oklahoma Youth Tobacco Survey and the Native American Behavioral Risk Factor Survey, as well as two large epidemiologic studies of chronic disease among American Indians-the Cherokee Diabetes Study and the Strong Heart Study. Three of these four sources of data involve research/surveys exclusively about American Indians. RESULTS: Nontraditional use of tobacco by American Indians occurs frequently, according to each instrument. Initiation to this habit begins in middle school and increases dramatically during high school. After age 50, reporting by individuals that they currently smoke declines steadily. CONCLUSIONS: Despite sampling different individuals for the surveys and different tribes for the epidemiologic research, results were comparable in age groups that overlapped. These findings support national data indicating that American Indians have higher prevalence rates of smoking than other racial/ethnic groups. American Indians report smoking on average about a half a pack of cigarettes per day. Individuals reporting using tobacco solely for ceremonial purposes were far fewer than habitual users. Buying tobacco products in American Indian smoke shops helps tribal economies; this fact needs to be considered for prevention programs to succeed.

Alcohol intake and glycemia in American Indians: the strong heart study.

The goal of this study was to explore the relationship between alcohol intake and glycemia and type 2 diabetes in American Indians aged 45 to 74 years. Data were obtained from participants in the Strong Heart Study, a longitudinal study of 13 American Indian communities in 3 geographic areas in the United States. Alcohol consumption was determined by self-reported alcohol intake history. Participants previously diagnosed with diabetes were excluded from the analysis. Analysis of covariance (ANCOVA) was used to estimate the adjusted means of blood glucose for alcohol intake categories. Logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) to estimate the association between alcohol intake and type 2 diabetes in the cross-sectional analysis and between alcohol intake and glucose intolerance using longitudinal data. Fasting and 2-hour plasma glucose concentrations showed an inverse J-shaped curve across categories of alcohol intake. Using never drinkers as the referent group in cross-sectional analysis, light drinkers had a significantly lower risk of having diabetes (OR, 0.66; 95% CI, 0.44 to 0.99); among drinkers, heavy drinkers had a higher, although not significant, prevalence of diabetes. Longitudinal analysis showed no significant worsening of glucose tolerance across levels of alcohol intake. Subanalyses stratified by body mass index (BMI) did not show differences between obese and non-obese participants in the relationship between alcohol intake and glucose tolerance. Although plasma glucose concentration showed a shallow, inverse J-shaped association across levels of increasing alcohol intake in American Indians aged 45 to 74 years, alcohol intake did not appear to significantly increase the risk for worsening glucose tolerance. Thus, alcohol intake does not appear to be a determinant of diabetes risk in this population.

Quantitative assessment of electrocardiographic strain predicts increased left ventricular mass: the Strong Heart Study.

OBJECTIVES: This study was designed to examine the relation of computer-measured ST depression (STdep) in the lateral precordial leads to the presence of left ventricular hypertrophy (LVH). BACKGROUND: Qualitative abnormalities of repolarization in the lateral precordial leads of the electrocardiogram, as manifested by the strain pattern of T-wave inversion and STdep, are markers for LVH and adverse prognosis. However, the independent relationship of increased left ventricular (LV) mass to quantitative measures of STdep in these leads remains unclear. METHODS: Electrocardiograms and echocardiograms were examined in the second Strong Heart Study examination in 1,595 American Indian participants without evident coronary disease. The absolute magnitude of ST segment deviation above or below isoelectric baseline was measured by computer in leads V(5) and V(6), and participants were grouped according to gender-specific quartiles of maximal STdep. Left ventricular hypertrophy was defined by indexed LV mass >49.2 g/m(2.7) in men and >46.7 g/m(2.7) in women. RESULTS: Increasing STdep was associated with older age, greater pulse pressure, serum fibrinogen levels and urinary albumin/creatinine ratios, and with stepwise increases in LV mass (145 +/- 28 vs. 150 +/- 33 vs. 156 +/- 36 vs. 164 +/- 43 g, p < 0.001), indexed LV mass (38.2 +/- 7.7 vs. 39.3 +/- 8.7 vs. 40.5 +/- 9.4 vs. 44.0 +/- 11.0 g/m(2.7), p < 0.001), and prevalence of LVH (11.6 vs. 19.1 vs. 21.5 vs. 31.2%, p < 0.001). After controlling for clinical differences, increasing STdep remained strongly associated with increased prevalence of LVH (p = 0.0001). CONCLUSIONS: In the absence of evidence of coronary disease, increasing STdep in the lateral precordial leads is associated with increasing LV mass and increased prevalence of anatomic LVH.