title: Ankle brachial index combined with Framingham Risk Score to predict cardiovascular events and mortality: a meta-analysis.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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lists and conference proceedings, and correspondence with experts was conducted to identify additional published and unpublished studies.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  Measurement of the ABI may improve the accuracy of cardiovascular risk prediction beyond the FRS.
authors.forename: F G R
authors.initials: FG
authors.lastname: Fowkes
authors.forename: G D
authors.initials: GD
authors.lastname: Murray
authors.forename: I
authors.initials: I
authors.lastname: Butcher
authors.forename: C L
authors.initials: CL
authors.lastname: Heald
authors.forename: R J
authors.initials: RJ
authors.lastname: Lee
authors.forename: L E
authors.initials: LE
authors.lastname: Chambless
authors.forename: A R
authors.initials: AR
authors.lastname: Folsom
authors.forename: A T
authors.initials: AT
authors.lastname: Hirsch
authors.forename: M
authors.initials: M
authors.lastname: Dramaix
authors.forename: G
authors.initials: G
authors.lastname: deBacker
authors.forename: J-C
authors.initials: JC
authors.lastname: Wautrecht
authors.forename: M
authors.initials: M
authors.lastname: Kornitzer
authors.forename: A B
authors.initials: AB
authors.lastname: Newman
authors.forename: M
authors.initials: M
authors.lastname: Cushman
authors.forename: K
authors.initials: K
authors.lastname: Sutton-Tyrrell
authors.forename: F G R
authors.initials: FG
authors.lastname: Fowkes
authors.forename: A J
authors.initials: AJ
authors.lastname: Lee
authors.forename: J F
authors.initials: JF
authors.lastname: Price
authors.forename: R B
authors.initials: RB
authors.lastname: d'Agostino
authors.forename: J M
authors.initials: JM
authors.lastname: Murabito
authors.forename: P E
authors.initials: PE
authors.lastname: Norman
authors.forename: K
authors.initials: K
authors.lastname: Jamrozik
authors.forename: J D
authors.initials: JD
authors.lastname: Curb
authors.forename: K H
authors.initials: KH
authors.lastname: Masaki
authors.forename: B L
authors.initials: BL
authors.lastname: Rodríguez
authors.forename: J M
authors.initials: JM
authors.lastname: Dekker
authors.forename: L M
authors.initials: LM
authors.lastname: Bouter
authors.forename: R J
authors.initials: RJ
authors.lastname: Heine
authors.forename: G
authors.initials: G
authors.lastname: Nijpels
authors.forename: C D A
authors.initials: CD
authors.lastname: Stehouwer
authors.forename: L
authors.initials: L
authors.lastname: Ferrucci
authors.forename: M M
authors.initials: MM
authors.lastname: McDermott
authors.forename: H E
authors.initials: HE
authors.lastname: Stoffers
authors.forename: J D
authors.initials: JD
authors.lastname: Hooi
authors.forename: J A
authors.initials: JA
authors.lastname: Knottnerus
authors.forename: M
authors.initials: M
authors.lastname: Ogren
authors.forename: B
authors.initials: B
authors.lastname: Hedblad
authors.forename: J C
authors.initials: JC
authors.lastname: Witteman
authors.forename: M M B
authors.initials: MM
authors.lastname: Breteler
authors.forename: M G M
authors.initials: MG
authors.lastname: Hunink
authors.forename: A
authors.initials: A
authors.lastname: Hofman
authors.forename: M H
authors.initials: MH
authors.lastname: Criqui
authors.forename: R D
authors.initials: RD
authors.lastname: Langer
authors.forename: A
authors.initials: A
authors.lastname: Fronek
authors.forename: W R
authors.initials: WR
authors.lastname: Hiatt
authors.forename: R
authors.initials: R
authors.lastname: Hamman
authors.forename: H E
authors.initials: HE
authors.lastname: Resnick
authors.forename: J
authors.initials: J
authors.lastname: Guralnik
authors.forename: M M
authors.initials: MM
authors.lastname: McDermott
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000842:Ankle; D050197:Atherosclerosis / Q000503:physiopathology; D001794:Blood Pressure; D001916:Brachial Artery; D002318:Cardiovascular Diseases / Q000401:mortality* / Q000503:physiopathology*; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D014943:Global Health; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index