Based on its review of the evidence, the USPSTF recommended physicians screen pregnant patients for asymptomatic bacteriuria using a urine culture; this is a "B" recommendation.
However, the task force recommended against screening for ASB in nonpregnant patients -- a "D" recommendation.
Due to changes that occur during pregnancy, pregnant patients with ASB have an increased risk of developing urinary tract and kidney infections that can be harmful for both mother and infant. Pyelonephritis can damage the kidneys, lead to early birth and be life-threatening for the mother.
"Screening pregnant people for ASB can help lower the risk of serious infections and health problems for the mother and baby," said USPSTF member Melissa Simon, M.D., M.P.H., in a news release. "The task force recommends that clinicians screen all pregnant people for ASB at their first prenatal visit."
Those who screen positive should be treated with antibiotics to prevent infection.
"If you're not pregnant, the chances of getting ASB and developing a serious infection from it are small and are outweighed by the potential for serious side effects from taking antibiotics, as well as the growing concerns around antibiotic resistance," said task force member Chyke Doubeni, M.D., M.P.H., in the release. "For these reasons, the task force recommends against screening for ASB in adults who are not pregnant."
This final recommendation statement is consistent with the USPSTF's April 23 draft recommendation. It also is generally consistent with the task force's 2008 final recommendation, which the AAFP supported at the time.
It should be noted that since 2008, the recommendation grade for pregnant patients has changed from an A to a B because the balance of benefits and harms has shifted, but screening is still recommended, the USPSTF said.
The USPSTF commissioned a systematic evidence review to update its 2008 recommendation by evaluating the evidence on the potential benefits and harms of screening for and treatment of asymptomatic bacteriuria in community-dwelling adults, including pregnant patients.
The task force changed the grade for pregnant patients from an A to a B based on the reduced applicability of the previous evidence, which included outdated antibiotic treatment regimens, and newer evidence showed a significantly lower risk of pyelonephritis than found in previous reviews.
"In addition, there are newer concerns about antibiotic use, such as antimicrobial resistance and adverse changes to the microbiome (not addressed in current studies), leading to an increase in the magnitude of potential harms," the final recommendation noted. "These factors led the USPSTF to reduce assessments of certainty and magnitude of benefit, resulting in the change of grade."
Since 1996, the USPSTF said it has maintained an A recommendation for one-time screening for ASB with urine culture in pregnant patients between 12 and 16 weeks of gestation. The original 1996 final recommendation was reaffirmed in 2004 and again in 2008.
In 1996, the task force found insufficient evidence to recommend for or against screening in older women and women with diabetes. In a separate recommendation, the USPSTF recommended against screening patients who were asymptomatic or older adults who resided in an institution. In 2004, these recommendations were combined into a single recommendation against screening, which was reaffirmed in 2008.
A draft version of this final recommendation statement was posted for public comment on the USPSTF website from April 23 to May 20.
Some commenters requested more information about how the USPSTF assessed older evidence.
"The USPSTF recognizes that older studies have certain limitations," the task force's recommendation acknowledged. "However, in reviewing all available evidence on the benefits and harms of treating screen-detected asymptomatic bacteriuria in pregnant women, the USPSTF found the evidence to be adequate."
Several other commenters asked for clarification on the task force's rationale for changing the grade of the recommendation from an A to a B for pregnant patients.
The USPSTF replied that changes in grade may occur when evidence has increased or decreased and results in a change in the certainty or magnitude of net benefit.
"Newer evidence, such as the lower prevalence of pyelonephritis, and a better understanding of the harms associated with antibiotic use changed the USPSTF's assessment of both the certainty (from high to moderate certainty) and net benefit of screening (from substantial to moderate net benefit), leading to the grade change," the final recommendation said.
The AAFP's Commission on Health of the Public and Science plans to review the USPSTF's final recommendation statement and evidence summary and will then determine the Academy's stance on the recommendation.
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