New Sheffield Table for Assessing Coronary Risks
In Britain, five leading groups of experts have issued joint treatment recommendations in patients at risk for heart disease. These recommendations include the initiation of aspirin and antihypertensive therapy when the risk of heart disease is 15 percent over 10 years. The use of statin drugs is also recommended when coronary risk is 15 percent over 10 years.
These and other recommendations depend on an ability to estimate risk in individual patients on a routine basis and to accurately identify the target group of patients with 15 percent risk over 10 years. The Sheffield table, which is based on the Framingham risk function, is one of the tools used to estimate coronary risk for primary prevention.
Wallis and colleagues modified the Sheffield table by basing it on the ratio of total cholesterol to high-density lipoprotein (HDL) cholesterol and age, sex, smoking, diabetes and hypertension (see the accompanying table). They tested this version of the table in a random sample of 1,000 adults living in Scotland.
TABLE 1
Sheffield Table for Primary Prevention of Cardiovascular Disease
NOTE: READ BEFORE USING TABLE.
- Do not use for secondary prevention: patients with MI, angina, PVD, non-hemorrhagic stroke, TIA, or diabetes with microvascular complications have high CHD risk. Treat mild hypertension: treat with aspirin; and treat with statin if serum cholesterol >=193 mg per dL (5.0 mmol per L).
- Treat hypertension above mild range (average >=160 or >=100 mm Hg).
- Treat mild hypertension (140 to 159 or 90 to 99 mm Hg) with target organ damage (LVH, proteinuria, renal impairment) or with diabetes (type 1 or 2).
- Consider drug treatment only after 6 months of appropriate advice on smoking, diet and repeated BP measurements.
- Use average of repeated total: HDL-C measurements. If HDL-C is not available, assume 46 mg per dL (1.2 mmol per L).
- Those with total:HDL-C ratio >=8.0 may have familial hyperlipidemia.
- The table underestimates CHD risk in:
- LVH on ECG (risk doubled; add 20 years to age)
- Family history of premature CHD (add 6 years)
- Familial hyperlipidemia
- British Asians
INSTRUCTIONS
- Choose table for men or women.
- Hypertension means SBP >=140 mm Hg or DBP >=90 mm Hg or on antihypertensive treatment.
- Identify correct column for hypertension, smoking and diabetes.
- Identify row showing age.
- Read off total:HDL-C ratios at intersection of column and row. If there is an entry, measure serum cholesterol:HDL ratio. If no entry, lipids need not be measured unless familial hyperlipidemia is suspected.
- If total:HDL-C ratio confers CHD risk of 15%, consider treatment of mild hypertension (SBP 140 to 159 mm Hg or DBP 90 to 99 mm Hg) and with aspirin.
- If total:HDL-C ratio confers CHD risk of 30%, consider statin if serum cholesterol >=193 mg per dL (5.0 mmol per L).
- Decision on statin at CHD risk between 15% to 30% depends on local policy.
- The table can be used to assess CHD risk at an older age.
HDL = high-density lipoprotein; CHD = coronary heart disease; MI = myocardial infarction; PVD = peripheral vascular disease; TIA = transient ischemic attack; LVH = left ventricular hypertrophy; BP = blood pressure; HDL-C = high-density lipoprotein cholesterol; ECG = electrocardiograph; SBP = systolic blood pressure; DBP = diastolic blood pressure.
Reprinted with permission from Wallis EJ, Ramsay LE, Ul Haq I, Ghahramani P, Jackson PR, Rowland-Yeo K, et al. Coronary and cardiovascular risk estimation for primary prevention: validation of a new Sheffield table in the 1995 Scottish health survey population. BMJ 2000;320:672.
The sample was selected to be representative of the Scottish adult population. Risk was assessed for each participant by two physicians. For each participant, the risk of cardiovascular disease was calculated using data from the Framingham studies to provide a gold standard. The accuracy of the Sheffield tables in predicting coronary risk was estimated by comparison with the Framingham estimates.
The study group included 562 (56.2 percent) women, 299 (29.9 percent) smokers and 16 (1.6 percent) patients with diabetes. The mean age was 49 years, mean blood pressure was 132/75 mm Hg and the mean 10-year coronary risk function by Framingham function was 7.2 percent. The Sheffield table had a 97 percent sensitivity and 95 percent specificity for coronary risk of 15 percent or greater over 10 years. Negative tests had a predictive value of 99.5 percent; positive tests had a predictive value of 73 percent. The false-positive results all had risks in the range of 10 to 15 percent.
The authors conclude that the simple table correctly identified about 97 percent of patients most likely to benefit from aspirin and statin drugs in primary prevention of coronary disease. While the Sheffield table identified patients who definitely should be offered treatment, the authors point out that it should not be used to deny treatment to people close to treatment thresholds.
ANNE D. WALLING, M.D.
Wallis EJ, et al. Coronary and cardiovascular risk estimation for primary prevention: validation of a new Sheffield table in the 1995 Scottish health survey population. BMJ March 11, 2000;320:671-6.
EDITOR'S NOTE: This article reflects a growing trend in British general practice literature to provide practical advice and tools for practitioners to use in primary prevention of the major causes of morbidity and mortality. This issue of BMJ contains 10 articles on such topics and several examples of charts and techniques to calculate level of risk. The Sheffield tables are easy to use and, as shown by the study, can accurately identify asymptomatic candidates for intervention. Interestingly, the British authors place emphasis on avoiding the expense of unnecessary testing in low-risk patients and identifying the high-risk group. Besides helping to strategize ways to avoid coronary disease, using the tables with patients might also have a powerful educational effect. The "big three"--hypertension, smoking and diabetes--dominate the tables. Patients may quickly appreciate how avoiding or controlling certain risk factors directly and substantially reduces the risk of heart disease.--a.d.w.
Copyright © 2000 by the American Academy of Family Physicians.
This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. Contact afpserv@aafp.org for copyright questions and/or permission requests.
