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HSTAT: Guide to Clinical Preventive Services, 3rd Edition: Recommendations and Systematic Evidence Reviews, Guide to Community Preventive Services U.S. Preventive Services Task Force Evidence Syntheses, formerly Systematic Evidence Reviews

25. Screening for Cervical Cancer

Systematic Evidence Review

Number 25

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

http://www.ahrq.gov

Contract No. 290-97-0011 Task No. 3 Technical Support of the U.S. Preventive Services Task Force

Prepared by: Research Triangle Institute/University of North Carolina 3040 Cornwallis Road PO Box 12194 Research Triangle Park, NC 27709 Katherine E. Hartmann, MD, PhD Susan A. Hall, MS Kavita Nanda, MD, MHS John F. Boggess, MD Dennis Zolnoun, MD

January 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.top link

Preface

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/clinic/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/clinic/uspstfix.htm), through the National Guideline Clearinghouse (http://www.ngc.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.


Carolyn Clancy, M.D. Robert Graham, M.D.
Acting Director Director, Center for Practice and
Agency for Healthcare Reseach and Quality      Technology Assessment
  Agency for Healthcare Research and Quality



The authors of this report are responsible for its content. Statements in the report should not be construed as endorsement by the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services of a particular drug, device, test, treatment, or other clinical service.


* The USPSTF is an independent panel of experts in primary care and prevention first convened by the U.S. Public Health Service in 1984. The USPSTF systematically reviews the evidence on the effectiveness of providing clinical preventive services--including screening, counseling, immunization, and chemoprevention--in the primary care setting. AHRQ convened the third USPSTF in November 1998 to update existing Task Force recommendations and to address new topics.top link

Structured Abstract

Context:

Methods that improve detection of serious cervical lesions while minimizing excess screening are the key to advancing cervical cancer prevention.top link

Objective:

To examine the evidence about benefits and harms of screening among older women (ages 65 and older) and those who have had hysterectomies, and to examine the diagnostic performance of new technologies and human papilloma virus (HPV) testing for detecting cervical lesions.top link

Data Sources:

We identified English-language articles on cervical neoplasia, cervical dysplasia, and screening from a comprehensive search of the MEDLINE database from 1995 through June 2000. In addition, we used published systematic reviews, the second Guide to Clinical Preventive Services, and peer review to assure a complete update of specific topics.top link

Study Selection:

We included articles that reported on screening for squamous cell carcinoma of the cervix if they included the age distribution of the study population and presented analyses stratified by age or if they included hysterectomy status as a covariate. For diagnostic tools, we required that the test be used as part of a screening strategy, that the method be compared with a reference standard, and that all cells of a 2x2 table can be completed.top link

Data Extraction:

We extracted the following data from articles addressing screening among older women and those who have had a hysterectomy: study design, objectives, location and timeframe, source of the data (e.g., population-based registry), participants, screening program used, outcomes and measures, and results relevant to age and screening interval. For articles about diagnostic tests, we extracted study design, test methods, location, patient population, outcome measures (emphasizing documentation of the reference standard), prevalence of lesions, and test characteristics including sensitivity, specificity, and predictive values. We used scoring checklists to summarize strengths of the publications; we also evaluated the validity of each article and the overall quality of the evidence.top link

Data Synthesis:

The evidence about age and hysterectomy is observational, predominantly from population- or care-based data. The findings are consistent: risk of cervical cancer or abnormalities falls with age; high-grade and more severe lesions are detected in fewer than 1 per 1,000 Pap tests among women older than 60 who have had prior screening; and longer histories of prior normal Pap tests further reduces risk. After hysterectomy, high-grade vaginal lesions are rare, fewer than 2 to 4 per 10,000 tests. The literature about new diagnostic tools is limited by lack of histologically validated performance. Using tools such as liquid cytology, neural-net rescreening, and computer-based review algorithms improves sensitivity; however, this improvement is predominantly for detection of low-grade lesions. The impact on specificity is poorly documented. Sensitivity of HPV testing for screening detection of high-grade lesions is competitive with conventional cytology (roughly 82%); specificity is lower (78%); and negative predictive value is good (99%). For triage of women with abnormal Pap tests, sensitivity for detecting high-grade lesions is 85%, specificity is 60%, and negative predictive value is 97%.top link

Conclusion:

The yield of screening among older women who have been previously screened decreases with age; if recommendations are not modified, older women are disproportionately likely to have evaluations for false-positive findings. The prior recommendation of the US Preventive Services Task Force to discontinue Pap testing after hysterectomy for benign disease is supported. For making decisions about screening modality in US populations, evidence about these new technologies for cytology screening and HPV testing is currently limited. Controlled trials and prospective cost evaluation of new screening strategies in each of these areas are required. Important trials will be completed in 2001 that may clarify our conclusions.top link


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