R Dhangana, TP Murphy, MJ Pencina, MB R Dhangana, TP Murphy, MJ Pencina, MB Ristuccia, JV Cerezo, D TsaiRistuccia, JV Cerezo, D Tsai

Prevalence of Low Ankle-Brachial Index, Elevated Plasma Fibrinogen and CRP Among Those Otherwise at Low-Intermediate Cardiovascular Events’ Risk: Data from the National Health and Nutrition Examination Survey (NHANES) 1999-2004

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• No Financial, Commercial, or any other conflict of interest for any author.

Introduction• CHD is highly prevalent and responsible for 1 in 5

deaths in US1.

• 1.2 million people suffer coronary attack every year; about 40% die as a result of the attack2.

• While primary medical prevention is shown to be very effective, at least 25% of MIs or sudden cardiac deaths occur with little prior warning of cardiovascular disease risk3.

• Identifying people for prevention is important 1. Deaths and percentage of total death for the 10 leading causes of death: United States,

2002-2003. National Center of Health Statistics.2. Heart Attack and Angina Statistics. American Heart Association (2003). 3. Myerburg RJ, Kessler KM, Castellanos A. Sudden cardiac death: epidemiology,

transient risk, and intervention assessment. Ann Intern Med 1993; 119:1187-97.

Introduction• Risk assessment is usually done using Framingham Risk

variables– 75% of adults are low-intermediate risk– But 85% of MI’s/sudden deaths occur in low-intermediate risk

• Abnormal ABI, elevated plasma fibrinogen and plasma CRP levels have been shown to be associated with increased risk of CHD events and mortality even in those at low-intermediate CHD risk1-3.

• However, prevalence estimates of abnormal ABI, fibrinogen and CRP among those not considered at high risk for CHD events have not been reported.

1.1. Fowkes FG, Murray GD,, et al. JAMA 2008; 300:197-208Fowkes FG, Murray GD,, et al. JAMA 2008; 300:197-2082.2. Danesh J, Lewington S, et al. JAMA 2005; 294:1799-809.Danesh J, Lewington S, et al. JAMA 2005; 294:1799-809.3.3. Montecucco F, Mach F. Clin Interv Aging 2008; 3:341-9.Montecucco F, Mach F. Clin Interv Aging 2008; 3:341-9.

OBJECTIVES

• To obtain U.S. population prevalence estimates for abnormal ABI, fibrinogen, and/or CRP for individuals without known “CHD-equivalence” with low or intermediate Framingham Risk score having

Definitions

• “High” Framingham Risk: >=20% 10-year risk of heart attack or coronary sudden death

• Population without “CHD equivalence”: no history of coronary heart disease or stroke, and without diabetes)

• Abnormal ABI=ABI <0.9 in either leg• Elevated plasma fibrinogen (>=400 mg/dl)• Elevated plasma CRP (>3mg/L)

STUDY POPULATION • Data from 1999-2004 NHANES

– NHANES: a large, multicenter survey of the U.S. civilian non-institutionalized population conducted by NCHS of CDC

• Population sampled to be representative of the overall U.S. population.

INCLUSION CRITERIA

• Age 40 and older – ABI, fibrinogen, CRP and FRS variables

available

• Participants with hx of diabetes, CHD, stroke or atherosclerotic vascular disease were excluded from further analyses.

• After all exclusions →→ 6,292 men and women were included.

Interviews & Physical Examinations

• Histories and Physical Examinations

• Blood tests and ankle brachial index– Standard ABI methods

STATISTICAL METHODS

• FRS was calculated based on the use of “Framingham” risk factors tables1-2 applied to NHANES data.

• Prevalence estimates (with CIs) were determined for abnormal ABI, fibrinogen and CRP in low-int FRS and high FRS categories.

1. NHANES: Analysis and Reporting Guideline (http://www.cdc.gov/nchs/data/nhanes/nhanes_03_04/nhanes_analytic_guidelines_dec_2005.pdf). 2. Anonymous. ATP III final report. Circulation 2002; 106:3143-421.

ResultsResults

Prevalence of ABI < 0.9, elevated fibrinogen (>=400 mg/dl), and elevated CRP (>3mg/L) in Adults Aged 40 years and older, NHANES

1999-2004; n = 6292**No known prevalent history of CHD, Stroke, Diabetes, or Atherosclerotic Vascular Disease

% (95% CI)

Abnl ABI 3.7 (3.3, 4.1)

Abnl fibrinogen 17.3 (14.7, 19.8)

Abnl CRP 37.9 (36.0, 39.7)

Framingham Risk Score vs. ABI: n = 5459

ResultsResults

Normal ABI ≥ 0.9 Abnl ABI < 0.9

Low/Int FRS 97.0% (96.0-98.0%) 3.0% (2.5-3.4%)3.0% (2.5-3.4%)

High FRS 89.5% (80.2-98.8%) 10.5% (8.1-12.8%)

Framingham Risk Score vs. Fibrinogen : n = 6292

Normal fibrinogen Elevated fibrinogen

Low/Int FRS 83.1% (80.2-86.0%) 16.9% (14.3-19.5%)

High FRS 72.0% (64.0-79.8%) 28.0% (22.5-32.6%)

P-value P-value <.0001<.0001

P-value P-value <.0001<.0001

Normal CRP Elevated CRP

Low/Int FRS 61.3% (60.0-63.6%) 38.7% (36.9-40.6%)38.7% (36.9-40.6%)

High FRS 53.9% (47.2-59.6%) 46.1% (40.4-51.7%)

Framingham Risk Score vs. CRP: n = 6292

P-value P-value <.0012<.0012

ResultsResults

FRS vs. either abnl ABI or Fibrinogen or CRP : n = 6292

Normal Abnormal/Elevated

Low/Int FRS 55.3% (52.7-57.8%) 44.7% (42.6-47.0%)44.7% (42.6-47.0%)

High FRS 43.8% (37.1-49.4%) 56.2% (49.4-64.0%)

P-value <.0001P-value <.0001

CONCLUSION• Prevalence of abnl ABI, fibrinogen, CRP is

high even in those without “high FRS”

• This is known to correlate with increased events despite “low-intermediate” risk

• Use in screening could be effective and improve public health