TP Murphy, R Dhangana, SH Ahn, JR Coll, TP Murphy, R Dhangana, SH Ahn, JR Coll, WR Hiatt, MB Ristuccia, JV CerezoWR Hiatt, MB Ristuccia, JV Cerezo

Prevalence of Abnormal Ankle-Brachial Index among Subjects with Low-Intermediate Framingham Risk Score

Disclosure Information

• 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.

• 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).

Introduction

• “High” risk = prior heart attack, stroke, atherosclerotic vascular disease; diabetes mellitus; “high” Framingham Risk Score (>20% 10-year risk of CV event)

• Framingham Risk Score – multivariable risk prediction algorithm using known variables (age, gender, smoking status, blood pressure, blood pressure medications, LDL)

Introduction

• BUT – at least 60% of CHD events occur in individuals not known to be high-risk;

– almost two third of events occur in individuals at either low or intermediate FRS1,2

• How can they be identified for prevention??

1. Brindle P, Emberson J, et al. BMJ 2003; 327:12672. Orford JL, Sesso HD et al. Am Heart J 2002; 144:95-100.

Introduction

• Abnormal ABI has been shown to be associated with increased risk of CHD events and mortality even in those at low-intermediate CHD risk1-2. – 6X risk of events, 3X risk of death

• ABI screening is popular

• Prevalence estimates of abnormal ABI among older screening populations with low-intermediate FRS has not been reported.

1.1. Fowkes FG, Murray GD,, et al. JAMA 2008; 300:197-208Fowkes FG, Murray GD,, et al. JAMA 2008; 300:197-208

2.2. Allison MA, Hiatt WR, et al. J Am Coll Cardiology 2008; 51(13):1292-8.Allison MA, Hiatt WR, et al. J Am Coll Cardiology 2008; 51(13):1292-8.

OBJECTIVES

• To obtain prevalence of abnormal ABI in a screening population of older individuals without known “CHD-equivalence” conditions and with low or intermediate Framingham Risk score

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 and/or >1.4 in either leg

STUDY POPULATION • A multicenter cross-sectional study conducted

in conjunction with Legs for Life®, a national free public screening program, conducted at 23 sites during 2007-09.

• The study advertisement message was designed to triage participants to enrich the population for screening who are not known to have PAD.

INCLUSION CRITERIA

• Age 18 and older individuals, who presented for Legs for Life® Screening and consented to participate in the study– ABI and FRS variables available

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

• After all exclusions →→ 822 men and women were included.

Interviews & Physical Examinations

• Data on demographics (age, gender, race, and ethnicity), anthropometry (height, weight and waist circumference), medical history (smoking, DM, HTN, hyperlipidemias, and prevalent PAD, CHD, TIA and stroke), Intermitted Claudication by San Diego Questionnaire, and BP measurements were collected

• 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 PEDAL Study data.

• Prevalence estimates were determined for abnormal ABI in low-int FRS and high FRS categories.

1. Anonymous. ATP III final report. Circulation 2002; 106:3143-421. 2. D'Agostino RB Sr, Vasan RS, et al. Circulation 2008; 117:743-53.

Results: Baseline Characteristics according to ABI; n=822, without known CHD, Stroke, TIA, or DM

Abnormal ABI (< 0.9 and/or >1.4)

Normal ABI P-Value

Age, mean (SD), y 65.8±13.0 63.6±12.0 0.08

Gender, Men, no. (%) Women, no. (%)

49 (19.5%)68 (11.9%)

202 (80.5%)503 (88.1%)

0.003

SBP, mean (SD) 138.0±21.5 138.20.1 0.961

Hypertension % 53 (14.9%) 303 (85.1%) 0.623

Fasting Glucose, mean (SD), mg/dl 97.0±12.0 97.2±16.2 0.934

LDL Cholesterol, mean (SD), mg/dl 110.3±36.5 115.8±36.8 0.202

HDL Cholesterol, mean (SD), mg/dl 52.2±15.5 53.7±18.7 0.485

Current Smoker, no. (%) 17 (22.4%) 59 (77.6%) 0.03

Framingham Risk Score vs. ABI, PEDAL Study 2007-2009; n = 822**No known prevalent history of CHD, Stroke, TIA or DM

Abnl ABI (< 0.9 and/or >1.4)

Normal ABI Total , no. (Column %)

Low FRS, no. (%) 29 (11.3%) 227 (88.7%) 256 (31.1%)

Int FRS, no. (%) 53 (12.8%) 361 (87.2%) 414 (50.4%)

High FRS, no. (%) 35 (23.0%) 117 (77.0%) 152 (18.5%)

Total, no. (%) 117 (14.2%) 705 (85.8%) 822

P-Value 0.03

CONCLUSION

• Prevalence of abnormal ABI is high even in those without “high FRS”

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

• Use in screening has potential to improve risk prediction

ACKNOWLEDGEMENTS• Society of Interventional Radiology Foundation• Pedal Study Sites– Baptist Memorial Hospital Memphis, Memphis, TN– Christiana Care Health Services, Newark, DE– Health First, Melbourne, FL– Kadlec Medical Center, Richland, WA– Kings Daughters Medical Center, Ashland, KY– Lancaster General Hospital, Lancaster, PA– Little Rock Cardiology Clinic, Little Rock, AR– Marquette Hospital, Marquette, MI– Mary Rutan Hospital, Bellefontaine, OH– Medical Center of Plano, Plano, TX– Rhode Island Hospital, Providence, RI– Scott and White Hospital, Temple, TX– Southwest Washington Medical Center, Vancouver, WA– The Community Hospital, Munster, IN– Forsyth Medical Center, Winston-Salem, NC– Riverview Hospital, Indianapolis, IN– Medical University of South Carolina, Charleston, SC

Thank You