Prevention Guidelines for Chemoprophylaxis, Screening, and Education

It would be impossible for any clinician to conduct an evidence-based review of every preventive strategy, and to synthesize all studies into a unified clinical recommendation. There are several organizations and academic bodies that routinely review the data and make recommendations for clinical practice.

The United States Preventive Services Task Force (USPSTF)

The U.S. Preventive Services Task Force (USPSTF) was first convened in 1984 by the U.S. Public Health Service, and published the first edition of the Guide to Clinical Preventive Services in 1989. Since 1998 the Agency for Healthcare Research and Quality (AHRQ) convenes the USPSTF, which is the leading independent panel of experts in prevention and primary care. Representatives on the panel include private-sector (non-government) family medicine physicians, general internists, pediatricians, obstetrician-gynecologists, and nursing professionals. The USPSTF conducts rigorous assessments of the scientific evidence for the effectiveness of a broad range of clinical preventive services, including screening, counseling, and chemoprophylaxis. As stated previously, the USPSTF recommendations are considered the “gold standard” for clinical preventive services.

Who are the recommendations for?

“The USPSTF evaluates the benefits of individual services based on age, gender, and risk factors for disease; makes recommendations about which preventive services should be incorporated routinely into primary medical care and for which populations; and identifies a research agenda for clinical preventive care” (AHRQ, 2008).

Recommendations issued by the USPSTF are intended for use in the primary care setting and provide clinicians with information about the evidence behind each recommendation, allowing health care providers and patients to make informed decisions about implementation. The recommendations of the USPSTF are made for asymptomatic populations.

Evidence Based Grades for USPSTF Recommendations

The USPSTF makes recommendations by assessing:

  • the quality of evidence supporting a specific preventive service and;
  • the magnitude of net benefit in providing the service.

The United States Preventive Services Task Force (USPSTF) updated its definitions of the grades it assigns to recommendations and now includes “suggestions for practice” associated with each grade. These definitions apply to USPSTF recommendations released after May 2007.

USPSTF Grade Definitions for recommendations released after May 2007
Grade Definition Suggestions for Practice
A The USPSTF recommends the service. There is high certainty that the net benefit is substantial. Offer or provide this service.
B The USPSTF recommends the service. There is high certainty that the net benefit is moderate or there is moderate certainty that the net benefit is moderate to substantial. Offer or provide this service.
C The USPSTF recommends against routinely providing the service. There may be considerations that support providing the service in an individual patient. There is at least moderate certainty that the net benefit is small. Offer or provide this service only if other considerations support the offering or providing the service in an individual patient.
D The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits. Discourage the use of this service.
I The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the service. Evidence is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined. Read the clinical considerations section of USPSTF Recommendation Statement. If the service is offered, patients should understand the uncertainty about the balance of benefits and harms.

The USPSTF has also defined the levels of certainty regarding net benefit of a service as either high,moderate, or low; visit the USPSTF website for further details on these certainty grades. The USPSTF defines certainty as “likelihood that the USPSTF assessment of the net benefit of a preventive service is correct.”

Electronic Access to USPSTF Guidelines

The AHRQ has created an electronic resource called the Electronic Preventive Services Selector (epSS) for clinicians to search for the latest USPSTF recommendations on the web or via smartphone / PDA apps.

You can look up recommendations by individual topic or individual patient demographics and risk factors. The recommendations are updated frequently, and e-mail notifications are available whenever new guidelines are released.

Read the case below and try using the epSS tool to find the answers:

The Case of Y.S.


Returning to our Case:
Y.S. is 24 year old white non-pregnant female medical student who presents to you in student health clinic today for her first visit. She has no complaints but just wanted “a check up”. She is generally healthy and had only a past medical history of acne that has resolved. She takes no medications currently and has no known drug allergies. She has no history of surgeries and no significant family history. Y.S. denies any mental health history. She has been sexually active only with her boyfriend for three years and they use condoms exclusively. Y.S. has no gynecologic or urologic complaints. This patient denies any intimate partner violence and feels she has a “good relationship” with her boyfriend. Y.S. has never smoked or used recreational drugs. Y.S. states that she no longer exercises routinely because her studies keep her very busy. She drinks one or two “Cosmos” on weekends, and does not drive a motor vehicle but her boyfriend does have a car.

According to the United States Preventive Services Task Force (USPSTF), which one of the following routine clinical preventive services is highly recommended (Grade A) because there is high certainty that the net benefit is substantial and should be offered to Y.S. based on her profile?

  1. Screening for asymptomatic bacteriuria.
  2. Counseling to reduce driving while under the influence of alcohol or riding with drivers who are alcohol-impaired.
  3. Serological screening for Herpes Simplex Virus (HSV).
  4. Behavioral counseling to promote physical activity.
  5. Screening for Chlamydia infection.

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