title: Derivation and validation of REASON: a risk score identifying candidates to screen for peripheral arterial disease using ankle brachial index.
abstract: BACKGROUND
  The recommendation of screening with ankle brachial index (ABI) in asymptomatic individuals is controversial. The aims of the present study were to develop and validate a pre-screening test to select candidates for ABI measurement in the Spanish population 50-79 years old, and to compare its predictive capacity to current Inter-Society Consensus (ISC) screening criteria.
  
  
  RESULTS
  Two population-based cross-sectional studies were used to develop (n = 4046) and validate (n = 3285) a regression model to predict ABI < 0.9. The validation dataset was also used to compare the model's predictive capacity to that of ISC screening criteria. The best model to predict ABI < 0.9 included age, sex, smoking, pulse pressure and diabetes. Assessment of discrimination and calibration in the validation dataset demonstrated a good fit (AUC: 0.76 [95% CI 0.73-0.79] and Hosmer-Lemeshow test: χ(2): 10.73 (df = 6), p-value = 0.097). Predictions (probability cut-off value of 4.1) presented better specificity and positive likelihood ratio than the ABI screening criteria of the ISC guidelines, and similar sensitivity. This resulted in fewer patients screened per diagnosis of ABI < 0.9 (10.6 vs. 8.75) and a lower proportion of the population aged 50-79 years candidate to ABI screening (63.3% vs. 55.0%).
  
  
  CONCLUSIONS
  This model provides accurate ABI < 0.9 risk estimates for ages 50-79, with a better predictive capacity than that of ISC criteria. Its use could reduce possible harms and unnecessary work-ups of ABI screening as a risk stratification strategy in primary prevention of peripheral vascular disease.
authors.affiliation: Research Unit in Primary Care, Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol) and Primary Care Services, Catalan Institute of Health, Girona, Catalunya, Spain. rramos.girona.ics@gencat.cat
authors.forename: Rafel
authors.initials: R
authors.lastname: Ramos
authors.forename: Jose Miguel
authors.initials: JM
authors.lastname: Baena-Díez
authors.forename: Miquel
authors.initials: M
authors.lastname: Quesada
authors.forename: Pascual
authors.initials: P
authors.lastname: Solanas
authors.forename: Isaac
authors.initials: I
authors.lastname: Subirana
authors.forename: Joan
authors.initials: J
authors.lastname: Sala
authors.forename: Maite
authors.initials: M
authors.lastname: Alzamora
authors.forename: Rosa
authors.initials: R
authors.lastname: Forès
authors.forename: Rafel
authors.initials: R
authors.lastname: Masiá
authors.forename: Roberto
authors.initials: R
authors.lastname: Elosua
authors.forename: María
authors.initials: M
authors.lastname: Grau
authors.forename: Ferran
authors.initials: F
authors.lastname: Cordón
authors.forename: Guillem
authors.initials: G
authors.lastname: Pera
authors.forename: Fernando
authors.initials: F
authors.lastname: Rigo
authors.forename: Ruth
authors.initials: R
authors.lastname: Martí
authors.forename: Anna
authors.initials: A
authors.lastname: Ponjoan
authors.forename: Carlos
authors.initials: C
authors.lastname: Cerezo
authors.forename: Ramon
authors.initials: R
authors.lastname: Brugada
authors.forename: Jaume
authors.initials: J
authors.lastname: Marrugat
mesh_terms: D000368:Aged; D055109:Ankle Brachial Index; D058070:Asymptomatic Diseases; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D018579:Patient Selection; D058729:Peripheral Arterial Disease / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D013030:Spain