title: Low cardiorespiratory fitness and coronary artery calcification: Complementary cardiovascular risk predictors in asymptomatic type 2 diabetics.
abstract: BACKGROUND
  Despite its well-established prognostic value, cardiorespiratory fitness (CRF) is not incorporated routinely in risk assessment tools. Whether low CRF provides additional predictive information in asymptomatic type 2 diabetics beyond conventional risk scores and coronary artery calcification (CAC) is unclear.
  
  
  METHODS
  We studied 600 type 2 diabetics aged 55-74 years without known coronary heart disease. CRF was quantified in metabolic equivalents (METs) by maximal treadmill testing and categorized as tertiles of percent predicted METs (ppMETs) achieved. CAC was calculated by non-enhanced computed tomography scans. The individual and joint association of both measures with an outcome event of all-cause mortality, myocardial infarction or stroke, was determined over a mean follow-up period of 80 ± 16 months.
  
  
  RESULTS
  There were 72 (12%) events during follow-up. Low CRF was independently associated with event risk after adjustment for traditional risk factors and CAC (HR 2.25, 95% CI 1.41-3.57, p = 0.001). CRF (unfit/fit) allowed further outcome discrimination both amongst diabetics with low CAC scores (9.5% versus 2.0% event rate), and amongst diabetics with high CAC scores (23.5% versus 12.4% event rate), p < 0.001. The addition of CRF to a model comprising UKPDS and CAC scores improved the area under the curve for event prediction from 0.66 to 0.71, p = 0.03, with a positive continuous net reclassification improvement (NRI) of 0.451, p = 0.002.
  
  
  CONCLUSIONS
  CRF, quantified by ppMETs, provided independent prognostic information which was additive to CAC. Low CRF may identify asymptomatic diabetic subjects at higher risk for all-cause mortality, myocardial infarction or stroke, despite low CAC.
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center and The Ruth and Bruce Rappaport School of Medicine, Technion-Israel Institute of Technology, Haifa, Israel. Electronic address: barakzmd@gmail.com.
authors.forename: Barak
authors.initials: B
authors.lastname: Zafrir
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center and The Ruth and Bruce Rappaport School of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Mohanad
authors.initials: M
authors.lastname: Azaiza
authors.affiliation: Department of Radiology, Lady Davis Carmel Medical Center, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Gaspar
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center and The Ruth and Bruce Rappaport School of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Idit
authors.initials: I
authors.lastname: Dobrecky-Mery
authors.affiliation: Department of Radiology, Lady Davis Carmel Medical Center, Israel.
authors.forename: Mali
authors.initials: M
authors.lastname: Azencot
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center and The Ruth and Bruce Rappaport School of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Basil S
authors.initials: BS
authors.lastname: Lewis
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center and The Ruth and Bruce Rappaport School of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Ronen
authors.initials: R
authors.lastname: Rubinshtein
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center and The Ruth and Bruce Rappaport School of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: David A
authors.initials: DA
authors.lastname: Halon
mesh_terms: D000368:Aged; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism*; D002319:Cardiovascular System; D017023:Coronary Angiography / Q000379:methods; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000473:pathology*; D048909:Diabetes Complications / Q000175:diagnosis; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000503:physiopathology; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors
keywords: Cardiorespiratory fitness; Coronary artery calcification; Prediction; Risk score