title: Performance of the QRISK cardiovascular risk prediction algorithm in an independent UK sample of patients from general practice: a validation study.
abstract: OBJECTIVE
  To assess the performance of the QRISK score for predicting cardiovascular disease (CVD) in an independent UK sample from general practice and compare with the Framingham score.
  
  
  METHODS
  Prospective open cohort study.
  
  
  METHODS
  UK general practices contributing to the THIN and QRESEARCH databases.
  
  
  METHODS
  The THIN validation cohort consisted of 1.07 million patients, aged 35-74 years registered at 288 THIN practices between 1 January 1995 and 1 April 2006. The QRESEARCH validation cohort consisted of 0.61 million patients from 160 practices (one-third of the full database) with data until 1 January 2007. Patients receiving statins, those with diabetes or CVD at baseline were excluded.
  
  
  METHODS
  First diagnosis of CVD (myocardial infarction, coronary heart disease (CHD), stroke and transient ischaemic attack) recorded on the clinical computer system during the study period.
  
  
  METHODS
  Age, sex, smoking status, systolic blood pressure, total/high-density lipoprotein cholesterol ratio, body mass index, family history of premature CHD, deprivation and antihypertensive medication.
  
  
  RESULTS
  Characteristics of both cohorts were similar, except that THIN patients were from slightly more affluent areas and had lower recording of family history of CHD. QRISK performed better than Framingham for every discrimination and calibration statistic in both cohorts. Framingham overpredicted risk by 23% in the THIN cohort, while QRISK underpredicted risk by 12%.
  
  
  CONCLUSIONS
  This analysis demonstrated that QRISK is better calibrated to the UK population than Framingham and has better discrimination. The results suggest that QRISK is likely to provide more appropriate risk estimates than Framingham to help identify patients at high risk of CVD in the UK.
authors.affiliation: Division of Primary Care, 13th Floor, Tower Building, University Park, Nottingham NG2 7RD, UK. Julia.hippisley-cox@nottingham.ac.uk
authors.forename: J
authors.initials: J
authors.lastname: Hippisley-Cox
authors.forename: C
authors.initials: C
authors.lastname: Coupland
authors.forename: Y
authors.initials: Y
authors.lastname: Vinogradova
authors.forename: J
authors.initials: J
authors.lastname: Robson
authors.forename: P
authors.initials: P
authors.lastname: Brindle
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D002318:Cardiovascular Diseases / Q000209:etiology*; D015331:Cohort Studies; D005194:Family Practice / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000209:etiology; D006113:United Kingdom