The evidence in favor of screening and treatment of lipid disorders is strongest for middle-aged men (aged 45 to 70 years), particularly those of European ancestry, with elevated levels of LDL-C and moderate to high short-term risk of CHD events. The populations in these studies appear similar to those found in primary care practice. The probability of finding abnormal lipids and sufficient CHD risk to warrant treatment is high in this age group.
AFCAPS was the only primary prevention trial that enrolled postmenopausal women. The women in AFCAPS were older: mean age of 63 years compared with 58 years for men. These women appeared to have a relative risk reduction for first CHD events similar to that for men, but they had fewer CHD deaths. The trial was not designed with sufficient power to examine total mortality effects for either men or women (37).
Evidence from secondary prevention trials suggests that women will achieve reductions in total CHD events similar to those for men if they have similar baseline levels of risk. In the short term (up to 5 years), these total reductions will take the form primarily of fewer nonfatal MIs rather than fewer CHD deaths (60-63). The effect on total mortality for women remains unclear: the Scandinavian Simvastatin Survival Study of secondary prevention found a relative risk of 1.16 (95% CI=0.68 to 1.99) for total mortality (62). Data on total mortality for women have not yet been published from the other major trials of secondary prevention or primary prevention, and we have insufficient long-term data to measure the longitudinal effects of CHD event reduction on total and CHD mortality.
Thus, reducing lipid levels appears to be effective in reducing CHD events in postmenopausal women with abnormal lipids, but the magnitude of that effect appears smaller than that among men, at least in part because middle-aged women with lipid disorders are at lower absolute risk than middle-aged men. Accurate global risk assessment is important, because women tend to have higher TC levels but lower CHD risk than men of similar ages.
Few elderly people (older than age 70 years) have been studied in primary prevention settings. Some epidemiologic studies have found that the relative risk of elevated cholesterol is attenuated in elderly patients. However, older people generally have high levels of absolute risk of CHD events, so lipid-lowering therapy is likely to be effective in these patients, assuming that their risk of competing causes of mortality is not too high (i.e., that their life expectancy is sufficient to allow them to realize the benefits of therapy). Data from secondary prevention trials suggest that lipid lowering is as effective, or more effective, in older patients than in younger patients (11,63,64).
Whether screening for and treating lipid disorders in men aged 20 to 35 years and women aged 20 to 45 years yield important benefits is controversial (65,66).
Screening to identify and treat young adults at high immediate risk of CHD. Young adults in general are at very low absolute risk of CHD events over the short-to-medium term (5 to 10 years). Even if treatment of lipid disorders in young adults reduces risk to the same or greater extent that it does in middle-aged men, the benefits in terms of absolute risk reduction over that time period will be very small.
Screening has been considered as a means of identifying and treating the small number of patients with extreme lipid levels who would not be recognized as being at risk of CHD events on the basis of a family history of early CHD events, family history of lipid abnormalities, or the presence of two or more other CHD risk factors. If unrecognized, some patients, mainly those with extreme lipid levels from genetic lipid disorders, may have CHD events before universal screening begins at age 35 or 45 years. The actual number of people who would fit in this category has not been well quantified but appears to be small. About 10% of men aged 20 to 34 years and 7% of women aged 20 to 44 years have LDL-C levels greater than 160 mg/dL (8). The proportion that would qualify for screening because of having diabetes, a family history of premature CHD or familial hyperlipidemia, or multiple other risk factors has not been reported (17).
Treating young adults to reduce long-term CHD risk. The crucial issue for deciding whether to screen younger adults is the incremental effectiveness of earlier treatment compared with delayed treatment for preventing CHD events in middle age. High TC levels in young adults are clearly predictive of higher rates of future CHD events. Data from a cohort of Johns Hopkins University medical students show that the relative risk of future CHD events and CHD mortality among men aged 20 to 25 years who had cholesterol levels above the 75th percentile was two times greater than the relative risk among those at the 25th percentile (67).
Ideally, we would like to have information from a randomized controlled trial that examined the effect of early screening and treatment (compared with delayed screening and treatment) on CHD events and mortality. Because such a study does not exist and is unlikely to be performed owing to the long period of follow-up that would be required (30 years), we must use indirect data to examine the magnitude of the potential incremental benefit from early screening and treatment.
Such indirect evidence is presented in a systematic review and meta-analysis by Law et al. (68). These investigators estimated the magnitude of the risk attributable to lipid disorders at different ages from observational cohort data. They then examined the risk for CHD in people treated for lipid disorders. After 5 to 10 years of treatment, the CHD risk for people who had their cholesterol lowered to a given level was similar to the CHD risk for people whose cholesterol had been at that lower level throughout their lives. They concluded that the majority (about 80%) of the risk reduction from lipid therapy can be achieved after 5 to 10 years of treatment; the incremental benefit from beginning therapy earlier is, therefore, relatively small. In a similar meta-analysis and meta-regression, Fager and Wiklund (69) reached the same conclusion.
With the use of the Law et al. (68) results, one might conclude that the preferred approach is to delay screening and treatment until about 5 to 10 years before the time that the absolute risk of CHD events begins to rise to meaningful absolute levels. This approach will theoretically minimize the potential adverse effects of long-term therapy and unnecessary drug costs without reducing benefit substantially. Others have challenged this interpretation and its implications, based on data from angiographic and autopsy studies and the higher attributable risk from cholesterol in younger people (66).
The clinical approach to screening and treating African Americans does not appear to differ materially from the approach to Caucasian populations. Average TC levels do not differ meaningfully between African-American and Caucasian populations, although HDL-C levels are higher for African Americans. Although trial data on African Americans are scarce, there is no good reason to believe that African Americans will respond differently than European Americans at any given level of risk. Harms of drug therapy do not appear to be increased (70). However, formulas to calculate CHD risk (7,32) have been developed mostly in patients of European descent and may not generalize well to African Americans. Fewer data exist about the prevalence of lipid disorders and the benefits of screening and treatment among Native-American, African-American, and Hispanic populations. Further research and wider recruitment in clinical trials would enable investigators to develop better estimates of the benefits of screening and treatment in people of non-European descent.
The effectiveness of screening to reduce CHD is well established in men of European ancestry. Data for minorities, women, and older and younger adults, however, remain scarce, and more research on the benefits of screening and treatment in these populations is warranted. Of high priority is the efficacy of lipid therapy in men of non-European descent and in all women, the elderly, and younger people with multiple risk factors or with diabetes. The effect of screening on stroke, although clear in secondary prevention trials, remains unproven in primary prevention. Strategies to improve dietary interventions and more information on the effectiveness of dietary therapy are needed. The optimal frequency of screening and the age at which screening should be initiated or discontinued are both unsettled issues, and further data on improving the accuracy and efficiency of different screening strategies are needed as well. Because clinicians require practical approaches to assessing the risk of individual patients, additional research in this arena is also called for. Although hypertriglyceridemia is a risk factor for CHD, the importance of screening for this condition and the effectiveness of interventions to control it remain to be established; the role of novel risk factors such as homocysteine or C-reactive protein also deserve attention. Finally, analysis of the optimal sequencing and combinations of different efforts to decrease CHD events (e.g., aspirin, treatment of hypertension, smoking cessation activities) would help to clarify the timing and role of lipid-lowering therapy.
The evidence is good that identifying middle-aged men with lipid disorders and treating those with sufficient CHD risk reduces CHD events and CHD mortality. Treating those at highest risk (greater than 1.5% risk of CHD events per year) may also reduce total mortality. Screening middle-aged women, the elderly, and young adults with multiple risk factors and treating those at increased risk also appears to reduce CHD events. The balance of benefits and harms from screening and treating young adults is not clear from the available evidence but is unlikely to be large compared with starting at age 35 years in men and age 45 years in women.
This study was developed by the Research Triangle Institute-University of North Carolina at Chapel Hill (RTI-UNC) Evidence-based Practice Center under contract to the Agency for Healthcare Research and Quality (Contract No. 290-97-0011), Rockville, MD. We acknowledge the assistance of Jacqueline Besteman, J.D., M.A., EPC Program Officer; Sonya Sutton, BSPH, and Sheila White, of Research Triangle Institute; and Mark Dowell, M.A., of the UNC Cecil R. Sheps Center for Health Services Research.
This article is based on a more comprehensive Systematic Evidence Review which is available online at www.ahrq.gov/clinic/serfiles.htm.
The systematic evidence review on which this article is based was reviewed by content experts, including Scott M. Grundy, M.D., Ph.D., Southwestern Medical Center at Dallas; Robert Baron, M.D., University of California, San Francisco; Matthew Gilman, M.D., Harvard Medical School and Harvard Pilgrim Health Care; and Thomas Newman, M.D., University of California, San Francisco; professional organizations, including the American Academy of Family Physicians, the American Academy of Pediatrics, the American College of Obstetricians and Gynecologists, the American College of Physicians/American Society of Internal Medicine, the American College of Preventive Medicine, and the Canadian Task Force on Preventive Health Care; and U.S. Public Health Service agencies, including the Centers for Disease Control and Prevention, National Heart, Lung and Blood Institute, the National Institutes of Health; and the Veterans' Administration. Review by these individuals and groups does not necessarily imply endorsement of this article or of the accompanying recommendations of the U.S. Preventive Services Task Force.
The authors of this article are responsible for its contents, including any clinical or treatment recommendations. No statement in this article should be construed as an official position of the Agency for Healthcare Research and Quality, the U.S. Department of Health and Human Services, the Department of Defense, or Merck and Co.
1. Anderson KM, Castelli WP, Levy D. Cholesterol and mortality: 30 years of follow-up from the Framingham study. JAMA 1987, 257:2176-2180.
2. Neaton JD, Wentworth D. Serum cholesterol, blood pressure, cigarette smoking, and death from coronary heart disease: overall findings and differences by age for 316,099 white men: Multiple Risk Factor Intervention Trial Research Group. Arch Intern Med 1992, 152:56-64.
3. National Heart, Lung and Blood Institute, National Institutes of Health. National Cholesterol Education Program (NCEP). Available at: www.nhlbi.nih.gov/health/prof/heart/index.htm#chol. Accessed July 1999.
4. Gross C.P, Anderson G.F, Powe N.R. The relation between funding by the National Institutes of Health and the burden of disease. N Engl J Med 1999, 340:1881-1887.
5. Lloyd-Jones DM, Larson MG, Beiser A, Levy D. Lifetime risk of developing coronary heart disease. Lancet 1999, 353:89-92.
6. Centers for Disease Control and Prevention. National Center for Health Statistics. National Health and Nutritional Survey III (NHANES III). Available at: www.cdc.gov/nchs/about/major/nhanes/datatblelink.htm. Accessed January 2001.
7. Wilson PW, D'Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB. Prediction of coronary heart disease using risk factor categories. Circulation 1998, 97:1837-1847.
8. Centers for Disease Control and Prevention. National Center for Health Statistics. National Health and Nutritional Survey III (NHANES III). Available at: www.cdc.gov/nchs/about/major/nhanes/datalink.htm. Accessed January 2001.
9. Centers for Disease Control and Prevention. National Center for Health Statistics. National Health and Nutritional Survey III (NHANES III). Available at: www.cdc.gov/nchs/about/major/nhanes/hdlfem.pdf. Accessed January 2001.
10. Sempos CT, Cleeman JI, Carroll MD, et al. Prevalence of high blood cholesterol among U.S. adults. JAMA 1993, 269:3009-3014.
11. Grundy SM, Cleeman JI, Rifkind BM, Kuller LH. Cholesterol lowering in the elderly population: Coordinating Committee of the National Cholesterol Education Program. Arch Intern Med 1999, 159:1670-1678.
12. U.S. Preventive Services Task Force. Guide to Clinical Preventive Services, 2nd ed. Washington, DC: Office of Disease Prevention and Health Promotion, U.S. Government Printing Office, 1996.
13. Logan AG. Lowering the blood total cholesterol level to prevent coronary heart disease: Canadian Task Force on the Periodic Health Examination. Canadian Guide to Clinical Preventive Health Care. 1994:650-69.
14. American College of Physicians. Guidelines for using serum cholesterol, high-density lipoprotein cholesterol, and triglyceride levels as screening tests for preventing coronary heart disease in adults. Ann Intern Med 1996;124:515-7.
15. Garber AM, Browner WS, Hulley SB. Cholesterol screening in asymptomatic adults, revisited, Part 2. Ann Intern Med 1996, 124:518-531.
16. American Diabetes Association. American Diabetes Association: clinical practice recommendations 1999. Diabetes Care 1999;22 (suppl 1):S1-S114.
17. Pignone MP, Phillips CJ, Lannon CM, et al. Screening for lipid disorders. Systematic evidence review. Pub. No. AHRQ01-S004. Rockville, MD: Agency for Healthcare Research and Quality; 2001 forthcoming.
18. Cooper GR, Myers GL, Smith SJ, Schlant RC. Blood lipid measurements: variations and practical utility. JAMA 1992, 267:1652-1660.
19. National Heart, Lung and Blood Institute. National Heart, Lung, and Blood Institute recommendations on lipoprotein measurement. September 1995. Available at: http://www.nhlbi.nih.gov/health/prof/heart/chol/lipoprot.pdf. Accessed September 1999.
20. du Pleissis M, Ubbink JB, Vermaak WJ. Analytical quality of near-patient blood cholesterol and glucose determinations. Clin Chem 2000, 46:1085-1090.
21. Grover SA, Coupal L, Hu XP. Identifying adults at increased risk of coronary disease: how well do the current cholesterol guidelines work? JAMA 1995, 274:801-806.
22. Grover SA, Lowensteyn I, Esrey KL, Steinert Y, Joseph L, Abrahamowicz M. Do doctors accurately assess coronary risk in their patients? Preliminary results of the coronary health assessment study. Br Med J 1995, 310:975-978.
23. Caggiula AW, Watson JE, Milas NC, Olson MB, Kuller LH, Orchard TJ. Evaluating the efficacy of the National Cholesterol Education Program adult treatment guidelines: cholesterol lowering intervention program. Prev Med 1995, 24:485-491.
24. Hutchison B, Birch S, Evans CE, et al. Selective opportunistic screening for hypercholesterolemia in primary care practice. J Clin Epidemiol 1998, 51:817-825.
25. Isles CG, Ritchie LD, Murchie P, Norrie J. Risk assessment in primary prevention of coronary heart disease: randomized comparison of three scoring methods. Br Med J 2000, 320:690-691.
26. Austin MA, Hokanson JE, Edwards KL. Hypertriglyceridemia as a cardiovascular risk factor. Am J Cardiol 1998;81 (suppl 1):7B-12B.
27. Avins AL, Neuhaus JM. Do triglycerides provide meaningful information about heart disease risk? Arch Intern Med 2000, 160:1937-1944.
28. Brett AS. Psychologic effects of the diagnosis and treatment of hypercholesterolemia: lessons from case studies. Am J Med 1991, 91:642-647.
29. Tijmstra T. The psychological and social implications of serum cholesterol screening. Int J Risk Safety Med 1990, 1:29-44.
30. Havas S, Reisman J, Hsu L, Koumjian L. Does cholesterol screening result in negative labeling effects? Results of the Massachusetts Model Systems for Blood Cholesterol Screening Project. Arch Intern Med 1991, 151:113-119.
31. Irvine MJ, Logan AG. Is knowing your cholesterol number harmful? J Clin Epidemiol 1994, 47:131-145.
32. Wallis EJ, Ramsay LE, Ul Haq I, et al. Coronary and cardiovascular risk estimation for primary prevention: validation of a new Sheffield Table in the 1995 Scottish health survey population. Br Med J 2000;320:671-6.
33. Hingorani AD, Vallance P. A simple computer program for guiding management of cardiovascular risk factors and prescribing. Br Med J 1999, 318:101-105.
34. National Heart, Lung and Blood Institute. The Lipid Research Clinics Coronary Primary Prevention Trial results, II: the relationship of reduction in incidence of coronary heart disease to cholesterol lowering. JAMA 1984;251:365-74.
35. Frick M, Elo O, Haapa K, et al. Helsinki Heart Study: primary-prevention trial with gemfibrozil in middle-aged men with dyslipidemia. Safety of treatment, changes in risk factors, and incidence of coronary heart disease. N Engl J Med 1987;317:1237-45.
36. Shepherd J, Cobbe SM, Ford I, et al. Prevention of coronary heart disease with pravastatin in men with hypercholesterolemia: West of Scotland Coronary Prevention Study Group. N Engl J Med 1995, 333:1301-1307.
37. Downs JR, Clearfield M, Weis S, et al. Primary prevention of acute coronary events with lovastatin in men and women with average cholesterol levels: results of AFCAPS/TexCAPS, Air Force/Texas Coronary Atherosclerosis Prevention Study. JAMA 1998, 279:1615-1622.
38. Pignone MP, Phillips CJ, Mulrow CD. Use of lipid lowering drugs for primary prevention of coronary heart disease: a meta-analysis of randomized trials. Br Med J 2000, 321:983-986.
39. Hebert PR, Gaziano JM, Chan KS, Hennekens CH. Cholesterol lowering with statin drugs, risk of stroke, and total mortality: an overview of randomized trials. JAMA 1997, 278:313-321.
40. Warshafsky S, Packard D, Marks SJ, et al. Efficacy of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors for prevention of stroke. J Gen Intern Med 1999, 14:763-774.
41. White HD, Simes RJ, Anderson NE, et al. Pravastatin therapy and the risk of stroke. N Engl J Med 2000, 343:317-326.
42. Ebrahim S, Smith GD. Systematic review of randomised controlled trials of multiple risk factor interventions for preventing coronary heart disease. Br Med J 1997, 314:1666-1674.
43. Clarke R, Frost C, Collins R, Appleby P, Peto R. Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies. Br Med J 1997, 314:112-117.
44. Denke MA. Cholesterol-lowering diets: a review of the evidence. Arch Intern Med 1995, 155:17-26.
45. Tang JL, Armitage JM, Lancaster T, Silagy CA, Fowler GH, Neil HAW. Systematic review of dietary intervention trials to lower blood total cholesterol in free-living subjects. Br Med J 1998, 316:1213-1220.
46. Brunner E, White I, Thorogood M, Bristow A, Curle D, Marmot M. Can dietary interventions change diet and cardiovascular risk factors? A meta-analysis of randomized controlled trials. Am J Public Health 1997, 87:1415-1422.
47. Bakx JC, Stafleu A, van Staveren WA, van den Hoogen HJ, van Weel C. Long-term effect of nutritional counseling: a study in family medicine. Am J Clin Nutr 1997;65 (6 suppl):1946S-50S.
48. Imperial Cancer Research Fund OXCHECK Study Group. Effectiveness of health checks conducted by nurses in primary care: results of the OXCHECK study after one year. Br Med J 1994;308:308-12.
49. Imperial Cancer Research Fund OXCHECK Study Group. Effectiveness of health checks conducted by nurses in primary care: final results of the OXCHECK study. Br Med J 1995;310:1099-1104.
50. Baron JA, Gleason R, Crowe B, Mann JI. Preliminary trial of the effect of general practice based nutritional advice. Br J Gen Pract 1990, 40:137-141.
51. Lindholm LH, Ekbom T, Dash C, Eriksson M, Tibblin G, Schersten B. The impact of health care advice given in primary care on cardiovascular risk: CELL Study Group. Br Med J 1995, 310:1105-1109.
52. Pyke SD, Wood DA, Kinmouth AL, Thompson SG. Change in coronary risk and coronary risk factor levels in couples following lifestyle intervention. Arch Fam Med 1997, 6:354-360.
53. Robertson I, Phillips A, Mant D, et al. Motivational effect of cholesterol measurement in general practice health checks. Br J Gen Pract 1992, 42:469-472.
54. Roderick P, Ruddock V, Hunt P, Miller G. A randomized trial to evaluate the effectiveness of dietary advice by practice nurses in lowering diet-related coronary heart disease risk. Br J Gen Pract 1997, 47:7-12.
55. Elton PJ, Ryman A, Hammer M, Page F. Randomised controlled trial in northern England of the effect of a person knowing their own serum cholesterol concentration. J Epidemiol Community Health 1994, 48:22-25.
56. Hanlon P, McEwen J, Carey L, et al. Health checks and coronary risk: further evidence from a randomised controlled trial. Br Med J 1995, 311:1609-1613.
57. Strychar IM, Champagne F, Ghadirian P, Bonin A, Jenicek M, Lasater TM. Impact of receiving blood cholesterol test results on dietary change. Am J Prev Med 1998, 14:103-110.
58. Miller TD, Balady GJ, Fletcher GF. Exercise and its role in the prevention and rehabilitation of cardiovascular disease. Ann Behav Med 1997, 19:220-229.
59. Tran ZV Weltman A. Differential effects of exercise on serum lipid and lipoprotein levels seen with changes in body weight: a meta-analysis. JAMA 1985, 254:919-924.
60. Walsh JM, Grady D. Treatment of hyperlipidemia in women. JAMA 1995, 274:1152-1158.
61. Lewis SJ, Sacks FM, Mitchell JS, et al. Effect of pravastatin on cardiovascular events in women after myocardial infarction: the cholesterol and recurrent events (CARE) trial. J Am Coll Cardiol 1998, 32:140-146.
62. Miettinen TA, Pyorala K, Olsson AG, et al. Cholesterol-lowering therapy in women and elderly patients with myocardial infarction or angina pectoris: findings from the Scandinavian Simvastatin Survival Study (4S) Circulation 1997, 96:4211-4218.
63. The Long-term Intervention with Pravastatin in Ischaemic Disease (LIPID) Study Group. Prevention of cardiovascular events and death with pravastatin in patients with coronary heart disease and a broad range of initial cholesterol levels. N Engl J Med 1998;339:1349-57.
64. Lewis SJ, Moye LA, Sacks FM, et al. Effect of pravastatin on cardiovascular events in older patients with myocardial infarction and cholesterol levels in the average range: results of the Cholesterol and Recurrent Events (CARE) trial. Ann Intern Med 1998, 129:681-689.
65. Hulley SB, Newman TB, Grady D, Garber AM, Baron RB, Browner WS. Should we be measuring blood cholesterol levels in young adults? JAMA 1993, 269:1416-1419.
66. LaRosa JC, Pearson TA. Cholesterol screening guidelines consensus, evidence, and the departure from common sense. Circulation 1997, 95:1651-1653.
67. Klag MJ, Ford DE, Mead LA, et al. Serum cholesterol in young men and subsequent cardiovascular disease. N Engl J Med 1993, 328:313-318.
68. Law MR, Wald NJ, Thompson SG. By how much and how quickly does reduction in serum cholesterol concentration lower risk of ischaemic heart disease? Br Med J 1994, 308:367-372.
69. Fager G, Wiklund O. Cholesterol reduction and clinical benefit. Arterioscler Thromb Vasc Biol 1997, 17:3527-3533.
70. Jacobson TA, Chin MM, Curry CL, et al. Efficacy and safety of pravastatin in African Americans with primary hypercholesterolemia. Arch Intern Med 1995;155:1900-1906.
[a]Pignone: Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
[b]Phillips: Office for Prevention and Health Services Assessment, Air Force Medical Operations Agency, San Antonio, TX.
[c]Atkins: Center for Practice and Technology Assessment, Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services, Rockville, MD.
[d]Teutsch: Outcomes Research and Management, Merck & Co, Inc, West Point, PA.
[e]Mulrow: Department of Medicine, Audie Murphy VA Medical Center, San Antonio, TX.
[f]Lohr: Research Triangle Institute, Research Triangle Park, and University of North Carolina at Chapel Hill, Program on Health Outcomes and School of Public Health, Chapel Hill, NC.
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Source: Pignone MP, Phillips CJ, Atkins D, Teutsch SM, Mulrow CD, Lohr, KN. Screening and treating adults for lipid disorders. Am J Prev Med 2001;20 (3S):77-89 (http://www.elsevier.com/locate/ajpmonline).
The USPSTF recommendations based on this evidence review can be found in Screening Adults for Lipid Disorders: Recommendations and Rationale.
Internet Citation:
Screening and treating Adults for Lipid Disorders: Summary of the Evidence. Article originally in Am J Prev Med 2001;20 (3S):77-89. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/clinic/ajpmsuppl/pignone1.htm
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