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Prediction of CHD using risk factor categories

Prediction of CHD using risk factor categories. Circulation . 1998; 97: 1837-47. Introduction & objective. CHD is the leading cause of morbidity and mortality in Western countries. Risk factors have been determined.

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Prediction of CHD using risk factor categories

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  1. Prediction of CHD using risk factor categories Circulation. 1998; 97: 1837-47

  2. Introduction & objective • CHD is the leading cause of morbidity and mortality in Western countries. • Risk factors have been determined. • Data from follow-up study in free-living population provide the opportunities to • assess the efficacies of categorization of risk factors recommended by JNC-V and NCEP. • construct a score sheet for evaluating individual’s CHD risk.

  3. Basic information • Subjects: • From the original and offspring cohorts of Framingham Heart Study • 30~74 yrs (in 1971~1974) • 2489 men and 2856 women • Exclude persons with overt CHD • Follow up for 12 years

  4. Baseline risks • Blood Pressure • Regardless of antihypertensive medication • Total Cholesterol • HDL-C • LDL-C: Friedewald formula • Diabetes • Casual glucose>=150 or fasting glucose >=140 mg/dL • Smoker • Who smoked regularly during the previous 12 months categorical binary

  5. Outcome: initial CHD events • Coronary Heart Disease • “CHD”: angina pectoris, un/recognized MI, coronary insufficiency, CHD death. • “Hard CHD”: “CHD” excluding angina pectoris. • CHD status data from • Regular exams at the FHS clinic • Review medical records from outside physician office visits and hospitalization

  6. Baseline analysis 1 Stage II: SBP:160-179/ DBP:100-109 Stage III: SBP:180-209/ DBP:110-119 Stage IV: SBP:210+/ DBP:120+

  7. Baseline analysis 2

  8. Prospective analysis 1: incidence

  9. Prospective analysis 2: RR

  10. Prospective analysis 2: RR

  11. True CHD + True CHD － Predicted CHD + a c Predicted CHD － b d Efficacy of prediction • ROC curve • Continuous • Categorical • Risk factor sum (0~7 points) • Age (45+), • HBP (140+/90+ or medication), • Smoking, • Diabetes, • TC (240+), • LDL-C (160+), • HDL-C (35-).

  12. ROC curve women men C statistics: area under the curve

  13. C statistics (AUC) *:TC=total cholesterol

  14. Model construction • Covariates • Age • Cholesterol • Total cholesterol • LDL-C • HDL-C • Blood pressure • Diabetes • Smoking Cox’s proportional hazard model:

  15. Construct the risk score sheets • Multiple Cox regression: estimating beta coefficients

  16. CHD score sheet for men

  17. CHD score sheet for women

  18. 55 year-old man TC: 250 HDL-C: 39 BP: 146/88 No diabetes smoker L=4.4478 G=3.0975 A=1.3503 B=3.8587 P=1-0.900153.8587 =0.3336 Example: see appendix

  19. Example 4 2 1 2 0 2 11

  20. Summary & discussion • Categorical risk assessment performs as well as continuous one. • The score sheet provides a simpler method to evaluate one’s 10 year CHD risk. • Characteristics of selected covariates • Easily measured (esp. baseline in the ’70s) • With standard definition • More directed related to CHD • Obtained in both population

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