The Effective Health Care Program of the Agency for Healthcare Research and Quality, or AHRQ, recently posted summary guides for clinicians and consumers that discuss the treatment of high cholesterol and medications to reduce the risk of primary breast cancer in women.
Treating Cholesterol With Combination Therapy: Clinician's Guide(effectivehealthcare.ahrq.gov) summarizes the current clinical evidence on using combinations of lipid-lowering medications to treat high cholesterol. It was developed by AHRQ's John M. Eisenberg Center for Clinical Decisions and Communication Sciences at Oregon Health & Science University in Portland based on a systematic evidence review conducted by the University of Ottawa Evidence-based Practice Center in Ontario, Canada.
The guide is intended to help physicians prescribe appropriate cholesterol-lowering treatments to patients who have not reached their cholesterol goal on lower doses of statins. It covers the major classes of lipid-lowering medications, but it doesn't discuss dietary and lifestyle changes.
The systematic review on which the guide is based compared the following medication combinations with statin monotherapy:
- a statin plus a bile acid sequestrant;
- a statin plus ezetimibe, which is marketed as Zetia;
- a statin plus a fibrate;
- a statin plus niacin; and
- a statin plus omega-3 fatty acids.
Although the review examined more than 100 studies, various characteristics of those studies made it difficult to draw firm conclusions. The "Clinical Bottom Line" section of the guide lists the following findings:
- The evidence is insufficient to conclude that combination therapy leads to lower rates of clinical events and death (all-cause mortality and vascular death) than statin monotherapy. In these studies, clinical events included myocardial infarctions, strokes and the need for invasive vascular procedures.
- The evidence is insufficient to assess whether any combination regimen provides greater reduction in LDL cholesterol than statin monotherapy. Evidence is also insufficient for other intermediate outcomes, including total cholesterol, HDL cholesterol, and coronary artery and carotid intima thickening.
- The evidence is insufficient to draw conclusions about the rates of adverse events of combination therapy compared with statin monotherapy. The adverse events assessed in these studies included elevation of liver enzymes, myalgia, rhabdomyolysis and cancer.
Medications to Reduce the Risk of Primary Breast Cancer in Women: Clinician's Guide(effectivehealthcare.ahrq.gov), which also was produced by the Eisenberg Center at Oregon Health & Science University, is based on a systematic review conducted by the Oregon Evidence-based Practice Center. The guide summarizes the safety and effectiveness profiles of two medications -- tamoxifen and raloxifene -- that are approved for the prevention of primary breast cancer.
According to the guide, tamoxifen, which is marketed as Nolvadex, is widely used to treat early and advanced hormone-receptor positive breast cancer; raloxifene, which is marketed as Evista, is used primarily to treat osteoporosis. Although both medications are approved by the FDA to reduce the risk of primary breast cancer, they are rarely used for this purpose in the United States.
Regarding the effectiveness of tamoxifen and raloxifene for this use, the guide offers the following findings:
- Tamoxifen and raloxifene are both effective at reducing the risk of primary invasive breast cancer in women ages 35-70.
- Raloxifene and tamoxifen reduce the likelihood of a woman developing breast cancer by a similar amount.
Neither drug, however, was found to reduce all-cause mortality, according to the guide. Moreover, both raloxifene and tamoxifen increased the risk of thromboembolic events, and tamoxifen increased the risk of endometrial cancer.
The clinician summary guides and their consumer counterparts -- Treating High Cholesterol: A Guide for Adults(effectivehealthcare.ahrq.gov) and Reducing the Risk of Breast Cancer With Medicine: A Guide for Women(effectivehealthcare.ahrq.gov) -- are available online and in print.
Free print copies can be obtained by calling the AHRQ Publications Clearinghouse at (800) 358-9295. Reference AHRQ publication No. 09(10)-EHC024-3 for the clinician's guide on treating high cholesterol and publication No. 09(10)-EHC023-3 for the clinician's guide on preventing breast cancer. Print copies of the consumer guide on cholesterol therapy can be ordered using publication No. 09(10)-EHC024-A; the breast cancer prevention guide for women is available as publication No. 09(10)-EHC028-A.