Systematic Evidence Review

Number 13

Prepared for: Agency for Healthcare Research and Quality U.S. Department of Health and Human Services 2101 East Jefferson Street Rockville, MD 20852

http://www.ahrq.gov/

Contract No. 290-97-0018 Task Order No. 2 Technical Support of the U.S. Preventive Services Task Force

Prepared by: Oregon Health Sciences University Evidence-based Practice Center, Portland, Oregon Erin Leblanc M.D., M.P.H. Benjamin Chan, M.S. Heidi D. Nelson, M.D., M.P.H.

August 2002

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

AHRQ is the lead Federal agency charged with supporting research designed to improve the quality of health care, reduce its cost, address patient safety and medical errors, and broaden access to essential services. AHRQ sponsors and conducts research that provides evidence-based information on health care outcomes; quality; and cost, use, and access. The information helps health care decisionmakers -- patients and clinicians, health system leaders, and policymakers -- make more informed decisions and improve the quality of health care services.

The Agency for Healthcare Research and Quality (AHRQ) sponsors the development of Systematic Evidence Reviews (SERs) through its Evidence-based Practice Program. With guidance from the third U.S. Preventive Services Task Force* (USPSTF) and input from Federal partners and primary care specialty societies, two Evidence-based Practice Centers -- one at the Oregon Health Sciences University and the other at Research Triangle Institute-University of North Carolina -- systematically review the evidence of the effectiveness of a wide range of clinical preventive services, including screening, counseling, immunizations, and chemoprevention, in the primary care setting. The SERs -- comprehensive reviews of the scientific evidence on the effectiveness of particular clinical preventive services -- serve as the foundation for the recommendations of the third USPSTF, which provide age- and risk-factor-specific recommendations for the delivery of these services in the primary care setting. Details of the process of identifying and evaluating relevant scientific evidence are described in the "Methods" section of each SER.

The SERs document the evidence regarding the benefits, limitations, and cost-effectiveness of a broad range of clinical preventive services and will help to further awareness, delivery, and coverage of preventive care as an integral part of quality primary health care.

AHRQ also disseminates the SERs on the AHRQ Web site (http://www.ahrq.gov/uspstfix.htm) and disseminates summaries of the evidence (summaries of the SERs) and recommendations of the third USPSTF in print and on the Web. These are available through the AHRQ Web site (http://www.ahrgq.gov/uspstfix.htm), through the National Guideline Clearinghouse (http://www.ncg.gov), and in print through the AHRQ Publications Clearinghouse (1-800-358-9295).

We welcome written comments on this SER. Comments may be sent to: Director, Center for Practice and Technology Assessment, Agency for Healthcare Research and Quality, 6010 Executive Blvd., Suite 300, Rockville, MD 20852.

Although postmenopausal hormone replacement (HRT) therapy is widely used, its risks and benefits are not well understood. Some observational data suggest that HRT may reduce the risk of cognitive decline and dementia but results have been conflicting.

To review and evaluate studies of HRT for preventing cognitive decline and dementia in healthy postmenopausal women.

Studies with English-language abstracts identified in MEDLINE (1966-December 2000), HealthSTAR (1975-December 2000), PsychINFO (1984-December 2000); Cochrane Library databases; and articles listed in reference lists of key articles.

Randomized controlled trials and cohort studies were reviewed for the effects of HRT on cognitive decline; cohort and case-control studies were reviewed for dementia risk. No randomized controlled trials regarding dementia risk were identified.

Twenty-nine studies met inclusion criteria and were rated. Two reviewers rated study quality independently and 100% agreement was reached on Jadad scores and 80% agreement was reached on U.S. Preventive Services Task Force quality scores. A final score was reached through consensus if reviewers disagreed.

Studies of cognition were not combined quantitatively because of heterogeneous study design. Women symptomatic from menopause had improvements in verbal memory, vigilance, reasoning, and motor speed, but no enhancement of other cognitive functions. Generally, no benefits were observed in asymptomatic women. A Bayesian meta-analysis of 12 observational studies suggested that HRT was associated with a decreased risk of dementia (summary odds ratio, 0.66; 95% confidence interval, 0.53-0.82). However, possible biases and lack of control for potential confounders limit interpretation of these studies.

Eight studies received a poor quality rating, 3 fair, and 1 good. Studies did not contain enough information to assess adequately the effects of progestin use, various estrogen preparations or doses, or duration of therapy.

In women with menopausal symptoms, HRT may have specific cognitive effects, and future studies should target these effects. The meta-analysis found a decreased risk of dementia in HRT users but most studies had important methodological limitations.