title: Baseline reproducibility of B-mode ultrasonic measurement of carotid artery intima-media thickness: the European Lacidipine Study on Atherosclerosis (ELSA).
abstract: OBJECTIVE
  The European Lacidipine Study of Atherosclerosis (ELSA) is a prospective, randomized, double-blind, multi-national interventional trial to determine the effect of four-year treatment using the calcium antagonist lacidipine versus the beta-blocker atenolol on the progression of carotid atherosclerosis in 2259 asymptomatic hypertensive patients. B-mode ultrasound is used to measure the primary and secondary endpoints including the mean maximum intima-media thickness (IMT) of the carotid bifurcations and the common carotid arteries (CBM(max)), the mean maximum IMT of 12 standard carotid sites (M(max)) and the overall maximum IMT (T(max)). This paper reports the cross-sectional reproducibility of ultrasound measurements at baseline.
  
  
  METHODS
  To evaluate measurement reliability, each patient is scanned twice at baseline and again at four annual visits, with 80% of the replicate scans performed by the same sonographer and 20% by a different sonographer; 50% of the replicate scans are read by the same reader and the other 50% by different readers.
  
  
  RESULTS
  The overall coefficient of reliability (R) was 0.859 for CBM(max), 0.872 for M(max) and 0.794 for T(max). The reliability for CBM(max) was stable during the 1 3/4-year baseline period (R = 0.848 to 0.953) and was uniform among the 23 field centres (R = 0.798 to 0.926). Intra- and inter-reader reliability were 0.915 and 0.872 respectively, and intra-sonographer reliability was 0.866.
  
  
  CONCLUSIONS
  The results demonstrate that by implementing standardized protocols and strict quality control procedures, highly reliable ultrasonic measurements of carotid artery IMT can be achieved in large multi-national trials.
authors.affiliation: Division of Vascular Ultrasound Research, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27104, USA. ytang@wfubmc.edu
authors.forename: R
authors.initials: R
authors.lastname: Tang
authors.forename: M
authors.initials: M
authors.lastname: Hennig
authors.forename: B
authors.initials: B
authors.lastname: Thomasson
authors.forename: R
authors.initials: R
authors.lastname: Scherz
authors.forename: R
authors.initials: R
authors.lastname: Ravinetto
authors.forename: R
authors.initials: R
authors.lastname: Catalini
authors.forename: P
authors.initials: P
authors.lastname: Rubba
authors.forename: A
authors.initials: A
authors.lastname: Zanchetti
authors.forename: M G
authors.initials: MG
authors.lastname: Bond
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D001161:Arteriosclerosis / Q000000981:diagnostic imaging* / Q000188:drug therapy; D001262:Atenolol / Q000627:therapeutic use; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D004095:Dihydropyridines / Q000627:therapeutic use; D004311:Double-Blind Method; D005060:Europe; D006801:Humans; D015588:Observer Variation; D011446:Prospective Studies; D011786:Quality Control; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000295:instrumentation / Q000592:standards / Q000706:statistics & numerical data
chemical_list: D000319:Adrenergic beta-Antagonists; D002121:Calcium Channel Blockers; D004095:Dihydropyridines; C060285:lacidipine; D001262:Atenolol