@article {613, title = {Association of sleep-disordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study.}, journal = {JAMA}, volume = {283}, year = {2000}, month = {2000 Apr 12}, pages = {1829-36}, abstract = {

CONTEXT: Sleep-disordered breathing (SDB) and sleep apnea have been linked to hypertension in previous studies, but most of these studies used surrogate information to define SDB (eg, snoring) and were based on small clinic populations, or both.

OBJECTIVE: To assess the association between SDB and hypertension in a large cohort of middle-aged and older persons.

DESIGN AND SETTING: Cross-sectional analyses of participants in the Sleep Heart Health Study, a community-based multicenter study conducted between November 1995 and January 1998.

PARTICIPANTS: A total of 6132 subjects recruited from ongoing population-based studies (aged > or = 40 years; 52.8\% female).

MAIN OUTCOME MEASURES: Apnea-hypopnea index (AHI, the average number of apneas plus hypopneas per hour of sleep, with apnea defined as a cessation of airflow and hypopnea defined as a > or = 30\% reduction in airflow or thoracoabdominal excursion both of which are accompanied by a > or = 4\% drop in oxyhemoglobin saturation) [corrected], obtained by unattended home polysomnography. Other measures include arousal index; percentage of sleep time below 90\% oxygen saturation; history of snoring; and presence of hypertension, defined as resting blood pressure of at least 140/90 mm Hg or use of antihypertensive medication.

RESULTS: Mean systolic and diastolic blood pressure and prevalence of hypertension increased significantly with increasing SDB measures, although some of this association was explained by body mass index (BMI). After adjusting for demographics and anthropometric variables (including BMI, neck circumference, and waist-to-hip ratio), as well as for alcohol intake and smoking, the odds ratio for hypertension, comparing the highest category of AHI (> or = 30 per hour) with the lowest category (< 1.5 per hour), was 1.37 (95\% confidence interval [CI], 1.03-1.83; P for trend = .005). The corresponding estimate comparing the highest and lowest categories of percentage of sleep time below 90\% oxygen saturation (> or = 12\% vs < 0.05\%) was 1.46 (95\% CI, 1.12-1.88; P for trend <.001). In stratified analyses, associations of hypertension with either measure of SDB were seen in both sexes, older and younger ages, all ethnic groups, and among normal-weight and overweight individuals. Weaker and nonsignificant associations were observed for the arousal index or self-reported history of habitual snoring.

CONCLUSION: Our findings from the largest cross-sectional study to date indicate that SDB is associated with systemic hypertension in middle-aged and older individuals of different sexes and ethnic backgrounds.

}, keywords = {Adult, Aged, Cohort Studies, Cross-Sectional Studies, Female, Humans, Hypertension, Logistic Models, Male, Middle Aged, Obesity, Polysomnography, Sleep Apnea Syndromes, Snoring}, issn = {0098-7484}, doi = {10.1001/jama.283.14.1829}, author = {Nieto, F J and Young, T B and Lind, B K and Shahar, E and Samet, J M and Redline, S and D{\textquoteright}Agostino, R B and Newman, A B and Lebowitz, M D and Pickering, T G} } @article {1039, title = {Ankle brachial index combined with Framingham Risk Score to predict cardiovascular events and mortality: a meta-analysis.}, journal = {JAMA}, volume = {300}, year = {2008}, month = {2008 Jul 09}, pages = {197-208}, abstract = {

CONTEXT: Prediction models to identify healthy individuals at high risk of cardiovascular disease have limited accuracy. A low ankle brachial index (ABI) is an indicator of atherosclerosis and has the potential to improve prediction.

OBJECTIVE: To determine if the ABI provides information on the risk of cardiovascular events and mortality independently of the Framingham risk score (FRS) and can improve risk prediction.

DATA SOURCES: Relevant studies were identified. A search of MEDLINE (1950 to February 2008) and EMBASE (1980 to February 2008) was conducted using common text words for the term ankle brachial index combined with text words and Medical Subject Headings to capture prospective cohort designs. Review of reference lists and conference proceedings, and correspondence with experts was conducted to identify additional published and unpublished studies.

STUDY SELECTION: Studies were included if participants were derived from a general population, ABI was measured at baseline, and individuals were followed up to detect total and cardiovascular mortality.

DATA EXTRACTION: Prespecified data on individuals in each selected study were extracted into a combined data set and an individual participant data meta-analysis was conducted on individuals who had no previous history of coronary heart disease.

RESULTS: Sixteen population cohort studies fulfilling the inclusion criteria were included. During 480,325 person-years of follow-up of 24,955 men and 23,339 women, the risk of death by ABI had a reverse J-shaped distribution with a normal (low risk) ABI of 1.11 to 1.40. The 10-year cardiovascular mortality in men with a low ABI (< or = 0.90) was 18.7\% (95\% confidence interval [CI], 13.3\%-24.1\%) and with normal ABI (1.11-1.40) was 4.4\% (95\% CI, 3.2\%-5.7\%) (hazard ratio [HR], 4.2; 95\% CI, 3.3-5.4). Corresponding mortalities in women were 12.6\% (95\% CI, 6.2\%-19.0\%) and 4.1\% (95\% CI, 2.2\%-6.1\%) (HR, 3.5; 95\% CI, 2.4-5.1). The HRs remained elevated after adjusting for FRS (2.9 [95\% CI, 2.3-3.7] for men vs 3.0 [95\% CI, 2.0-4.4] for women). A low ABI (< or = 0.90) was associated with approximately twice the 10-year total mortality, cardiovascular mortality, and major coronary event rate compared with the overall rate in each FRS category. Inclusion of the ABI in cardiovascular risk stratification using the FRS would result in reclassification of the risk category and modification of treatment recommendations in approximately 19\% of men and 36\% of women.

CONCLUSION: Measurement of the ABI may improve the accuracy of cardiovascular risk prediction beyond the FRS.

}, keywords = {Adult, Age Factors, Aged, Aged, 80 and over, Ankle, Atherosclerosis, Blood Pressure, Brachial Artery, Cardiovascular Diseases, Cohort Studies, Confidence Intervals, Female, Global Health, Humans, Male, Middle Aged, Odds Ratio, Predictive Value of Tests, Risk Assessment, Risk Factors, Severity of Illness Index}, issn = {1538-3598}, doi = {10.1001/jama.300.2.197}, author = {Fowkes, F G R and Murray, G D and Butcher, I and Heald, C L and Lee, R J and Chambless, L E and Folsom, A R and Hirsch, A T and Dramaix, M and deBacker, G and Wautrecht, J-C and Kornitzer, M and Newman, A B and Cushman, M and Sutton-Tyrrell, K and Fowkes, F G R and Lee, A J and Price, J F and D{\textquoteright}Agostino, R B and Murabito, J M and Norman, P E and Jamrozik, K and Curb, J D and Masaki, K H and Rodr{\'\i}guez, B L and Dekker, J M and Bouter, L M and Heine, R J and Nijpels, G and Stehouwer, C D A and Ferrucci, L and McDermott, M M and Stoffers, H E and Hooi, J D and Knottnerus, J A and Ogren, M and Hedblad, B and Witteman, J C and Breteler, M M B and Hunink, M G M and Hofman, A and Criqui, M H and Langer, R D and Fronek, A and Hiatt, W R and Hamman, R and Resnick, H E and Guralnik, J and McDermott, M M} } @article {6803, title = {Development and validation of an ankle brachial index risk model for the prediction of cardiovascular events.}, journal = {Eur J Prev Cardiol}, volume = {21}, year = {2014}, month = {2014 Mar}, pages = {310-20}, abstract = {

BACKGROUND: The ankle brachial index (ABI) is related to risk of cardiovascular events independent of the Framingham risk score (FRS). The aim of this study was to develop and evaluate a risk model for cardiovascular events incorporating the ABI and FRS.

DESIGN: An analysis of participant data from 18 cohorts in which 24,375 men and 20,377 women free of coronary heart disease had ABI measured and were followed up for events.

METHODS: Subjects were divided into a development and internal validation dataset and an external validation dataset. Two models, comprising FRS and FRS + ABI, were fitted for the primary outcome of major coronary events.

RESULTS: In predicting events in the external validation dataset, C-index for the FRS was 0.672 (95\% CI 0.599 to 0.737) in men and 0.578 (95\% CI 0.492 to 0.661) in women. The FRS + ABI led to a small increase in C-index in men to 0.685 (95\% CI 0.612 to 0.749) and large increase in women to 0.690 (95\% CI 0.605 to 0.764) with net reclassification improvement (NRI) of 4.3\% (95\% CI 0.0 to 7.6\%, p = 0.050) and 9.6\% (95\% CI 6.1 to 16.4\%, p < 0.001), respectively. Restricting the FRS + ABI model to those with FRS intermediate 10-year risk of 10 to 19\% resulted in higher NRI of 15.9\% (95\% CI 6.1 to 20.6\%, p < 0.001) in men and 23.3\% (95\% CI 13.8 to 62.5\%, p = 0.002) in women. However, incorporating ABI in an improved newly fitted risk factor model had a nonsignificant effect: NRI 2.0\% (95\% CI 2.3 to 4.2\%, p = 0.567) in men and 1.1\% (95\% CI 1.9 to 4.0\%, p = 0.483) in women.

CONCLUSIONS: An ABI risk model may improve prediction especially in individuals at intermediate risk and when performance of the base risk factor model is modest.

}, keywords = {Adult, Aged, Aged, 80 and over, Ankle Brachial Index, Cardiovascular Diseases, Europe, European Continental Ancestry Group, Female, Humans, Male, Middle Aged, Models, Statistical, Predictive Value of Tests, Prognosis, Reproducibility of Results, Risk Assessment, Risk Factors, Sex Factors, Time Factors, United States, Young Adult}, issn = {2047-4881}, doi = {10.1177/2047487313516564}, author = {Fowkes, F G R and Murray, G D and Butcher, I and Folsom, A R and Hirsch, A T and Couper, D J and deBacker, G and Kornitzer, M and Newman, A B and Sutton-Tyrrell, K C and Cushman, M and Lee, A J and Price, J F and D{\textquoteright}Agostino, R B and Murabito, J M and Norman, Pe and Masaki, K H and Bouter, L M and Heine, R J and Stehouwer, C D A and McDermott, M M and Stoffers, H E J H and Knottnerus, J A and Ogren, M and Hedblad, B and Koenig, W and Meisinger, C and Cauley, J A and Franco, Oh and Hunink, M G M and Hofman, A and Witteman, J C and Criqui, M H and Langer, R D and Hiatt, W R and Hamman, R F} }