title: Annual progression of coronary calcification in trials of preventive therapies: a systematic review.
abstract: BACKGROUND
  Coronary artery calcification (CAC) measured by computed tomography is radiographic confirmation of atherosclerosis, predicts cardiovascular events, and has been evaluated as a surrogate measure in randomized trials.
  
  
  METHODS
  We performed a literature search for prospective randomized trials in which CAC was measured at baseline and at 1 year or more of follow-up. We computed the weighted mean annualized rate of CAC progression for a variety of therapies tested in these trials.
  
  
  RESULTS
  Ten trials (n = 2612) met our criteria and were included. Electron-beam, double-helix, and multislice computed tomography were used in 6, 2, and 2 trials, respectively. Agatston (8 trials) and volumetric (2 trials) methods were used for CAC evaluation. In 5 trials in subjects with cardiovascular disease (CVD) (n = 2135; age, ~64 years; ~39% women; follow-up, ~26 months), therapies included statins (n = 1370), placebo (n = 564), and antihypertensives (n = 201). In 5 trials in subjects with chronic kidney disease (n = 477; age, ~55 years; ~34% women; follow-up, ~14 months), interventions included low-phosphorus diet (n = 29), sevelamer hydrochloride (n = 229), and calcium-based phosphate binders (n = 219). The mean (SD) weighted annualized CAC increase overall and in patients with CVD and chronic kidney disease was 17.2% (6.7%), 16.9% (5.2%), and 18.4 (11.1%), respectively (P < .001). The rate among those assigned blinded placebo was 14.6% (1.0%) (2 trials). There was no consistent or reproducible treatment effect of any therapy on this outcome measured at 1 year.
  
  
  CONCLUSIONS
  The 1-year change in CAC does not appear to be a suitable surrogate end point for treatment trials in patients with CVD or chronic kidney disease.
authors.affiliation: William Beaumont Hospital, Royal Oak, MI 48073, USA. peteramccullough@gmail.com
authors.forename: Peter A
authors.initials: PA
authors.lastname: McCullough
authors.forename: Kavitha M
authors.initials: KM
authors.lastname: Chinnaiyan
mesh_terms: D002114:Calcinosis / Q000000981:diagnostic imaging* / Q000188:drug therapy; D002318:Cardiovascular Diseases / Q000517:prevention & control; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000188:drug therapy; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors; D014057:Tomography, X-Ray Computed