First Annual Report to Congress on High-Priority Evidence Gaps for Clinical Preventive Services - V

Table of Contents

V. Current Evidence Gaps Deserving of Further Research

There are many positive stories about the impact of USPSTF recommendations and tools. By definition, topics selected for review by the Task Force have a high burden of disease, with potentially important public health benefits for prevention if effective preventive services exist. Therefore, recommendations from the Task Force are likely to improve health when they are implemented appropriately and effectively.

However, significant gaps in key areas of knowledge limit the full realization of the benefits of evidence-based preventive services recommendations for the health of the entire population. With the Affordable Care Act, Congress recognized the opportunity for new research to provide the necessary evidence base upon which the USPSTF can build recommendations. Congress specifically charged the USPSTF with identifying and reporting to Congress each year on the critical evidence gaps in two areas: 1) areas where the current evidence is insufficient to make any recommendation on the use of a clinical preventive service, and 2) areas where evidence is needed to make recommendations for specific populations and age groups.

Congress Was Right: New Research and New Evidence Results in New USPSTF Recommendations

In the past, when the USPSTF has identified specific gaps in the evidence needed for it to make recommendations, researchers have responded by embarking on important work to fill those gaps. Research gaps have been successfully filled for several areas that until recently were without sufficient evidence. For example:

  1. New evidence led to updating screening for hearing loss in newborns from insufficient evidence to recommended: Screening for hearing loss in newborns was given an "I" rating for insufficient evidence in 2001. When the recommendation was updated in 2008, the Task Force was able to determine, on the basis of a new controlled trial, that the benefits of the service outweighed the harms, and gave it a positive recommendation ("B" grade).
  2. New evidence led to updating screening for obesity in children from insufficient evidence to recommended: Screening for obesity in children was given an "I" rating in 2004, but a number of new studies were included in an evidence review conducted for an update in 2010. Based on the new evidence, the USPSTF gave this service a "B" grade, indicating confidence that the service would lead to moderate net benefits (i.e., benefits that outweighed harms).
  3. Evidence gaps identified by the USPSTF have also led to research efforts on a larger scale: A major grants initiative by the National Institute on Drug Abuse (NIDA) that was initiated after a review by the Task Force indicated that there was insufficient evidence to recommend screening for drug abuse in primary care settings. The NIDA initiative provided funds for researchers to study the use of drug abuse screening in primary care to determine the effects of screening on health outcomes, directly addressing evidence gaps identified by the USPSTF in 2008.

In this first annual report to Congress, the members of the USPSTF have identified high-priority evidence gaps in the following three areas:

  1. Screening Tests
  2. Behavioral Interventions
  3. Clinical Preventive Services Targeting Specific Populations and Age Groups

The report concludes with a brief discussion of the importance of additional research on how to implement clinical preventive services into primary care.

Process for Prioritizing

To encourage research that closes critical evidence gaps identified by the USPSTF, the Task Force developed a systematic, reproducible process for prioritizing research on clinical preventive services for which it has issued "I" statements. This process intentionally builds on the evidence reviews utilized by the USPSTF to make recommendations. In the prioritization process, all current "I" statements were ranked on four domains: potential preventable burden, potential harms, potential costs, and current practice. "I" statements for behavioral intervention and counseling topics were ranked separately from those for screening topics. Whereas the ability of primary care-based interventions to lead directly to changes in health outcomes is more distant, the overall health burden related to health behaviors is often significant. However, because the harms of most counseling services are considered to be small, counseling topics have a lower priority rating when the previously described rating system is applied.

For some topics currently under review, the USPSTF has not yet determined if previously identified research gaps in the evidence still exist. Examples of these topics include screening for dementia, glaucoma, and peripheral arterial disease. In future reports to Congress, the USPSTF may make recommendations for research in these areas.

 A. High-Priority Evidence Gaps for Screening Tests

Below are four screening topics that the USPSTF has prioritized as having critical evidence gaps that may be addressed through research and that if filled are likely to result in important new recommendations:

  1. Screening for Coronary Heart Disease With New and Old Technologies
    Coronary heart disease is the most common cause of death in adults in the United States. While enormous progress has been made in helping Americans prevent and manage coronary heart disease, current screening techniques fail to identify many individuals who go on to have significant heart disease. In 2004 and 2009, the USPSTF identified significant evidence gaps in our understanding of how older technologies, such as electrocardiography, and new tests, including blood tests and computed tomography (CT) scans, may or may not improve our ability to prevent coronary heart disease. Targeted research is needed to examine the incremental benefits and harms associated with use of these technologies in addition to and potentially as replacements for current risk-based screening and treatment methods.
  2. Screening for Colorectal Cancer With New Modalities
    Colorectal cancer screening is effective in saving lives in adults older than age 50 years. However, many adults do not get screened. Recently developed technologies hold promise for extending the reach of colorectal cancer screening programs and screening the population more efficiently. In 2008, the USPSTF was unable to make a recommendation about newer screening modalities due to evidence gaps. Research is needed on fecal DNA testing and CT colonography that defines the benefits and harms of these screening tests in comparison with current well-established screening methods, and that explores and illuminates the acceptability of these tests among populations who are unwilling to undergo testing with currently recommended strategies.
  3. Screening for Hepatitis C
    Viral hepatitis C is the most common blood-borne pathogen in the United States and results in as many as 10,000 deaths each year. Fortunately most people who have the infection do not develop liver problems. In 2004, the USPSTF found that although there are good screening tests that accurately identify individuals who are infected with the hepatitis C virus, there was not enough evidence about whether treating asymptomatic individuals found to have the infection through screening programs resulted in more long-term benefits and fewer harms when compared with treating people when they become symptomatic. The Task Force concluded that more research is needed to better understand the progression of the disease and which individuals are at highest risk of suffering from liver damage. Studies are also needed to better understand if early treatment of hepatitis C infection leads to improved outcomes and which individuals will benefit the most from early treatment, and to evaluate the effect of diagnosis and treatment on quality of life.
  4. Screening for Hip Dysplasia While rare, developmental dysplasia of the hip (DDH) can be associated with disability in youth and throughout life. In 2006, the USPSTF concluded that a more complete understanding of the natural history of spontaneous resolution of hip instability and dysplasia is needed before it will be possible to develop an evidence-based strategy for screening newborns for hip abnormalities and treating those abnormalities. Given the infrequent occurrence of DDH, multicenter studies of interventions that measure functional outcomes (including long-term outcomes) in a standardized fashion are needed. Studies designed to identify valid and reliable radiological outcomes of DDH as proxy measures of functional outcomes are also needed.

 B. High-Priority Evidence Gaps for Behavioral Interventions

Below are three areas from the fields of behavioral intervention and health promotion that the USPSTF has prioritized as having critical evidence gaps that may be addressed through research and that if filled are likely to result in important new recommendations:

  1. Moderate- to Low-Intensity Counseling for Obesity
    The importance of obesity as a health problem in the United States is increasingly apparent. According to recent data, when obesity is defined as a body mass index of 30 kg/m2 or more, 30 percent of American men and women are obese. Being obese is associated with health problems such as an increased risk of coronary heart disease, type 2 diabetes, various types of cancer, gallstones, and disability. In addition, obesity is associated with increased risk of premature death and decreased quality of life. In 2003, the USPSTF concluded that the available evidence supported recommending high-intensity interventions for obese adults and that the evidence was insufficient to make a recommendation about the use of moderate- or low-intensity counseling together with behavioral interventions to promote sustained weight loss in obese adults. In 2010, the USPSTF recommended screening and intensive counseling for obese children ages 6 years and older. The Task Force is currently completing an update of its 2003 recommendation for adults. Future research is needed in many areas concerning screening and counseling for obesity in children and adults. Continued development and testing of counseling and behavioral interventions with better and longer followup are needed, especially to understand the potential contribution of moderate- and low- intensity counseling. Additional research should also examine the long-term outcomes and effects of interventions delivered to overweight children and adults.
  2. Interventions to Prevent Child Abuse and Neglect
    Approximately 1 million abused children are identified in the United States each year. Despite the dedication and hard work of people in many sectors, no one has discovered an effective role for the primary care system and primary care professionals in preventing child abuse and neglect. The Task Force recognizes that the solution to this issue will include many other efforts and hopes that needed research to find effective interventions initiated in primary care will be conducted. Early research suggests that clinician referrals to home visitation by nurses during pregnancy and early childhood may reduce child abuse and neglect in selected populations, but additional research is needed. Future research must examine both the potential benefits and the potential unintended harms of interventions aimed at preventing child abuse and neglect.
  3. Screening for Illicit Drug Use
    Illicit drug use and abuse is a serious problem in the United States and ranks among the 10 leading preventable risk factors for years of healthy life lost to death and disability in developed countries. In 2008, the Task Force found that there was insufficient evidence to make a recommendation about screening for illicit drug use in primary care practices. Studies are needed to determine whether interventions found effective for treatment-seeking individuals with symptoms of drug misuse are equally effective when applied to asymptomatic individuals identified through screening. In addition, observational studies are needed to establish more clearly the effects of treatment on long-term health outcomes, including morbidity and mortality.

 C. High-Priority Evidence Gaps in Clinical Preventive Services Targeting Specific Populations and Age Groups

For some clinical preventive services that have been well studied for the general population, important evidence gaps exist that prevent the USPSTF from making recommendations for targeted populations and age groups. This is often because these groups are underrepresented in health research. Prime examples of such groups are the elderly, children, and racial and ethnic minorities. In the past, women were also underrepresented in medical research. Greater inclusion of these populations in research will help the USPSTF to issue recommendations that can be used to improve the quality of preventive care available to all Americans and to eliminate disparities.

Below are four specific topics that the USPSTF has prioritized as having critical evidence gaps for targeted populations and age groups that may be addressed through research and that if filled are likely to result in important new recommendations:

  1. Screening for Osteoporosis in Men
    By 2012, approximately 12 million Americans older than age 50 years are expected to have osteoporosis. Osteoporotic fractures, particularly hip fractures, are associated with chronic pain and disability, loss of independence, decreased quality of life, and increased mortality. Although hip fractures are less common in men than in women, more than one-third of men who experience a hip fracture die within 1 year. In 2011, the USPSTF recommended screening for osteoporosis in women ages 65 years or older and in younger women at increased risk. However, the USPSTF found a lack of relevant studies on whether drug therapies reduce the risk for fractures in men who have no previous osteoporotic fractures. Because of this evidence gap, the USPSTF was unable to make a recommendation for men. Randomized trials of primary clinical fracture prevention in men who have osteoporosis are needed.
  2. Screening for Depression in Children
    Major depressive disorder (MDD) among youth is a disabling condition that is associated with serious long-term morbidity and risk of suicide. However, the majority of depressed youth are undiagnosed and untreated. In 2009, the USPSTF found inadequate evidence that screening tests accurately identify MDD in school-aged children, and that antidepressants (i.e., selective serotonin reuptake inhibitors [SSRIs] such as fluoxetine) reduce MDD symptoms in children. There are limited data on the benefits of psychotherapy and the benefits of psychotherapy plus SSRIs in children. Studies are also needed that examine collaborative care management approaches compared with usual clinical care, as well as epidemiologic studies that describe the prevalence of MDD in children in primary health care settings according to age, sex, and race/ethnicity. Observational studies of risks for longer-term outcomes associated with the use of antidepressants would also contribute to addressing current evidence gaps.
  3. Screening and Counseling for Alcohol Misuse in Adolescents
    High-risk alcohol use by adolescents is an important cause of preventable death and significant injury in this population. In 2004, the USPSTF found convincing evidence that screening and behavioral counseling for adults including pregnant women in primary care settings was effective. It found significant evidence gaps, however, regarding the effectiveness of interventions aimed at adolescents. More evidence is needed on the effects of alcohol misuse screening and counseling interventions targeting adolescents that can be implemented in primary care settings, or to which patients can be referred by primary care clinicians.
  4. Aspirin Use to Prevent Heart Attacks and Strokes in Adults Ages 80 Years and Older
    In 2009, the USPSTF found good evidence that aspirin decreases the incidence of myocardial infarction in men and ischemic strokes in women and recommended that primary care clinicians discuss aspirin use with middle-aged men and women. While aspirin use has significant benefits, it also has significant risks, including gastrointestinal bleeding. While the incidence of heart attack and stroke is high in older adults and thus the potential benefit of aspirin is large, the relationship between increasing age and gastrointestinal bleeding is also well established, and thus the potential harms are also large. The USPSTF did not find enough evidence to balance the potential benefits and harms of aspirin use to prevent cardiovascular disease in adults older than age 80 years. Given the continuing aging of the U.S. population and longer expected life spans, it is important to study the effectiveness of clinical prevention in older adults. Specifically, research is needed to understand the potential benefits and harms of aspirin use to prevent heart attacks and strokes in adults ages 80 years and older.

Even when the Task Force has not made an "I" statement about a specific service, it understands that there are issues for specific groups that need additional attention in order for all people to be able to benefit from prevention. There are many reasons why clinical preventive services may have differential impact for specific populations, including potential biologic and genetic differences and social determinants of health that vary among communities. Examples of clinical preventive services with differential impact include such diverse topics as screening for hepatitis B in Asian Americans, screening for diabetes in American Indians, and counseling about breastfeeding for African American women and families.

Gaps in Implementation Research

In addition to targeted research in the high-priority areas identified above, the USPSTF notes that there are also critical questions about how evidence on the effectiveness of clinical preventive services can best be implemented in primary care practices. Additional implementation and translational research in this area will increase the value of the work of the USPSTF. Specifically, research is needed to systematically evaluate the following:

  1. How do primary care professionals incorporate new evidence to change their practice?
  2. What are the most effective strategies to assist primary care professionals in the translation of evidence-based clinical preventive services into practice?
  3. How can primary care professionals share evidence with their patients to empower patients and families to make health care decisions about prevention?
  4. How can health information technology, including electronic health records and personal health records, be utilized to increase the number of Americans receiving recommended clinical preventive services?
  5. How can the USPSTF continue to improve its work to better meet the needs of primary care professionals and their patients?


    Current as of: December 2013
    Internet Citation: First Annual Report to Congress on High-Priority Evidence Gaps for Clinical Preventive Services - V. U.S. Preventive Services Task Force. December 2011.