Primary Care in Patients Without Vascular Disease
Primary Care in Patients Without Vascular Disease
In the United Kingdom, the current recommendation is that lipid-lowering drugs should be prescribed for primary prevention only to subjects with an absolute coronary risk (AR) greater than 15% in 5 years (i.e., myocardial infarction or angina). However, to achieve greater benefit it may be preferable to direct treatment to those patients showing the greatest absolute risk reduction (ARR). The aim of this study was to compare the characteristics of subjects eligible for lipid-lowering drugs based on the AR criteria or on an ARR of >4.45%. A prospective study was carried out over 29 months in primary care in a part of the United Kingdom with a prevalence of coronary disease nearly 20% above the national average. Risk factors were recorded in men and women aged 30-75 years who were being considered by their primary care physician for lipid-lowering drug therapy. Of the 2351 patients included in the study, 2139 (91%) and 101 (4.3%) were, respectively, below and above the criteria for treatment by both AR and ARR criteria. In 111 (4.7%) subjects, treatment was recommended based on only one of the criteria -- 82 on AR and 29 on ARR. Comparing these two groups, those treated on AR only were older (mean age 68.1 years [SD, 4.1] vs. 49.1 years [SD, 4.6]; p<0.0001) and had a lower total cholesterol (260 vs. 288 mg/dL; p=0.015); higher high-density lipoprotein cholesterol (50 vs. 43 mg/dL; p=0.003), lower low-density lipoprotein cholesterol (160 vs. 184 mg/dL; p=0.03), a lower total to high-density lipoprotein cholesterol ratio (5.4 vs. 7.1; p<0.0001), and lower triglycerides (258 vs. 435 mg/dL; p=0.007). The AR group also had a higher mean systolic blood pressure (170.9 vs. 158.9 mm Hg; p=0.013), presumably an attribute of their greater age. Although the AR and ARR groups did not show a difference in the proportion of males or diabetics, there was a significantly greater proportion of smokers in the latter group (72% vs. 35%; p=0.001). In conclusion, treatment recommendations based on AR alone would result in nontreatment of young subjects with significant hyperlipidemia and at high relative risk of coronary disease, whereas lipid-lowering drugs would be given preferentially to patients whose main coronary heart disease risk factors are age and hypertension but not hyperlipidemia. By contrast, treatment recommendations based on ARR ensure that lipid-lowering drugs are directed to patients who will derive the most benefit. Furthermore, delaying treatment in younger subjects at high relative risk but not high AR results in their accumulating significant coronary risk in the years before their AR exceeds an arbitrary threshold before lipid-lowering drugs are prescribed.
Prescribing lipid-lowering drugs is of proven benefit in the prevention of coronary events in those with and without established coronary heart disease (CHD). Nevertheless, cost implications necessitate targeting preventive treatment to patients who will derive the most benefit. In the United Kingdom, current recommendations, endorsed recently by the Department of Health in its National Service Framework, prioritize lipid-lowering drugs to patients with established vascular disease and to those without such disease whose CHD risk is greater than 3% per year. Although the overall relative risk reduction in coronary disease by statins of a little over 30% appears similar in all clinical trials irrespective of the subject characteristics, a restraint to using statins in primary prevention has been imposed to reduce the burden on the drug budget. The two primary prevention studies with statins, the West of Scotland Coronary Prevention Study (WOSCOPS) and the Air Force Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS), showed that despite a significant relative risk reduction of 31% and 37%, absolute benefit occurred in only 2.4% and 0.4% of patients, respectively. During the 5-year trial period, the event rates in the placebo groups were 7.9% and 1.1%, which was considerably less than 15%, the level above which present UK recommendations suggest lipid-lowering drugs should be prescribed. Although prescribing of statins is more cost-effective when applied to those at high absolute risk (AR) of CHD, it is usual in medicine to base the decision to treat on perceived benefit to the patient. Where treatment may be beneficial to all, but for economic reasons it has to be rationed, priority should be given to those who will derive the greatest benefit. Targeting treatment to those at greatest AR is valid only if the risk reduction achieved through treatment is equal in all patients, whatever their baseline characteristics. If absolute risk reduction (ARR) differs according to the characteristics of the patients, ARR, and consequently the "number needed to treat," will vary. Treatment based on ARR may be more cost-effective than using AR alone.
In this study, we used the Framingham equation, on which most cardiovascular predictive models are based, to calculate absolute cardiovascular risk. From AR, we computed the likely benefit from lipid-lowering treatment, expressed as the ARR. In a previous short report, we described the results of this approach when adopted by a group of 17 local general practices. We now describe the results following extension of our original study with recruitment of many more practices. We compared the baseline risk factors of patients who would be recommended for treatment based on their AR or their ARR and describe the concept of cumulative events prevented by treatment.
In the United Kingdom, the current recommendation is that lipid-lowering drugs should be prescribed for primary prevention only to subjects with an absolute coronary risk (AR) greater than 15% in 5 years (i.e., myocardial infarction or angina). However, to achieve greater benefit it may be preferable to direct treatment to those patients showing the greatest absolute risk reduction (ARR). The aim of this study was to compare the characteristics of subjects eligible for lipid-lowering drugs based on the AR criteria or on an ARR of >4.45%. A prospective study was carried out over 29 months in primary care in a part of the United Kingdom with a prevalence of coronary disease nearly 20% above the national average. Risk factors were recorded in men and women aged 30-75 years who were being considered by their primary care physician for lipid-lowering drug therapy. Of the 2351 patients included in the study, 2139 (91%) and 101 (4.3%) were, respectively, below and above the criteria for treatment by both AR and ARR criteria. In 111 (4.7%) subjects, treatment was recommended based on only one of the criteria -- 82 on AR and 29 on ARR. Comparing these two groups, those treated on AR only were older (mean age 68.1 years [SD, 4.1] vs. 49.1 years [SD, 4.6]; p<0.0001) and had a lower total cholesterol (260 vs. 288 mg/dL; p=0.015); higher high-density lipoprotein cholesterol (50 vs. 43 mg/dL; p=0.003), lower low-density lipoprotein cholesterol (160 vs. 184 mg/dL; p=0.03), a lower total to high-density lipoprotein cholesterol ratio (5.4 vs. 7.1; p<0.0001), and lower triglycerides (258 vs. 435 mg/dL; p=0.007). The AR group also had a higher mean systolic blood pressure (170.9 vs. 158.9 mm Hg; p=0.013), presumably an attribute of their greater age. Although the AR and ARR groups did not show a difference in the proportion of males or diabetics, there was a significantly greater proportion of smokers in the latter group (72% vs. 35%; p=0.001). In conclusion, treatment recommendations based on AR alone would result in nontreatment of young subjects with significant hyperlipidemia and at high relative risk of coronary disease, whereas lipid-lowering drugs would be given preferentially to patients whose main coronary heart disease risk factors are age and hypertension but not hyperlipidemia. By contrast, treatment recommendations based on ARR ensure that lipid-lowering drugs are directed to patients who will derive the most benefit. Furthermore, delaying treatment in younger subjects at high relative risk but not high AR results in their accumulating significant coronary risk in the years before their AR exceeds an arbitrary threshold before lipid-lowering drugs are prescribed.
Prescribing lipid-lowering drugs is of proven benefit in the prevention of coronary events in those with and without established coronary heart disease (CHD). Nevertheless, cost implications necessitate targeting preventive treatment to patients who will derive the most benefit. In the United Kingdom, current recommendations, endorsed recently by the Department of Health in its National Service Framework, prioritize lipid-lowering drugs to patients with established vascular disease and to those without such disease whose CHD risk is greater than 3% per year. Although the overall relative risk reduction in coronary disease by statins of a little over 30% appears similar in all clinical trials irrespective of the subject characteristics, a restraint to using statins in primary prevention has been imposed to reduce the burden on the drug budget. The two primary prevention studies with statins, the West of Scotland Coronary Prevention Study (WOSCOPS) and the Air Force Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS), showed that despite a significant relative risk reduction of 31% and 37%, absolute benefit occurred in only 2.4% and 0.4% of patients, respectively. During the 5-year trial period, the event rates in the placebo groups were 7.9% and 1.1%, which was considerably less than 15%, the level above which present UK recommendations suggest lipid-lowering drugs should be prescribed. Although prescribing of statins is more cost-effective when applied to those at high absolute risk (AR) of CHD, it is usual in medicine to base the decision to treat on perceived benefit to the patient. Where treatment may be beneficial to all, but for economic reasons it has to be rationed, priority should be given to those who will derive the greatest benefit. Targeting treatment to those at greatest AR is valid only if the risk reduction achieved through treatment is equal in all patients, whatever their baseline characteristics. If absolute risk reduction (ARR) differs according to the characteristics of the patients, ARR, and consequently the "number needed to treat," will vary. Treatment based on ARR may be more cost-effective than using AR alone.
In this study, we used the Framingham equation, on which most cardiovascular predictive models are based, to calculate absolute cardiovascular risk. From AR, we computed the likely benefit from lipid-lowering treatment, expressed as the ARR. In a previous short report, we described the results of this approach when adopted by a group of 17 local general practices. We now describe the results following extension of our original study with recruitment of many more practices. We compared the baseline risk factors of patients who would be recommended for treatment based on their AR or their ARR and describe the concept of cumulative events prevented by treatment.
