Estimating the benefits of modifying risk factors of cardiovascular disease: a comparison of primary vs secondary prevention.
OBJECTIVE
To compare the potential years of life saved (YOLS) associated with risk factor modification in the primary and secondary prevention of cardiovascular disease (CVD).


METHODS
The CVD life expectancy model estimates the risk of death due to coronary disease, stroke, and other causes based on the levels of independent risk factors (such as age, blood pressure, and blood lipid levels) found in the cohort of the Lipid Research Clinics. The model was validated by comparing its predictions with the observed fatal outcomes of 9 randomized clinical trials. We then estimated the YOLS associated with treating hyperlipidemia or hypertension among hypothetical patient groups with and without CVD at baseline. We defined high-risk patients as those with 3 risk factors (hyperlipidemia, cigarette smoking, and hypertension) and low-risk patients as those with isolated hypertension or hyperlipidemia.


RESULTS
The fatal events predicted by the model were consistent with the clinical trial results. Among men and women with hyperlipidemia without CVD, the forecasted benefits of lipid therapy were substantially greater among high-risk groups vs low-risk groups (4.74-0.78 YOLS vs 2.50-0.25 YOLS, respectively). Among those with CVD, the forecasted benefits of treatment were similar for both high-risk and low-risk groups (4.65-0.65 YOLS vs 3.84-0.58 YOLS, respectively). The results for hypertension therapy also demonstrated greater benefits for high-risk vs low-risk patients undergoing primary prevention therapy (1.34-0.29 YOLS vs 0.85-0.13 YOLS, respectively), and the forecasted benefits in secondary prevention were similar (1.26-0.23 YOLS vs 1.00-0.23 YOLS, respectively).


CONCLUSIONS
The clinical approach to risk factor modification in primary prevention should be different from that in secondary prevention. The forecasted benefits of therapy among patients without CVD are greatest in the presence of other risk factors. Among those with CVD, the benefits of therapy are equivalent, thereby obviating the need to target high-risk patients.
Grover
S A
SA
Centre for the Analysis of Cost-Effective Care, Montreal General Hospital, Department of Medicine, McGill University, Quebec, Canada.
Paquet
S
S
Levinton
C
C
Coupal
L
L
Zowall
H
H
D002318:Cardiovascular Diseases / Q000209:etiology / Q000401:mortality / Q000517:prevention & control*; D005260:Female; D005544:Forecasting; D006801:Humans; D006949:Hyperlipidemias / Q000628:therapy; D006973:Hypertension / Q000628:therapy; D008017:Life Expectancy; D008297:Male; D008875:Middle Aged; D011322:Primary Prevention; D012307:Risk Factors; D055502:Secondary Prevention