What does a 'B' grade mean?

• A. High certainty of substantial net benefit; the service should be offered.
• B. The net benefit is moderate; the service should be offered.
• C. The service should not be offered due to harms outweighing benefits.
• D. There is insufficient evidence to assess benefits or harms.

Answer: (B)

USPSTF grading expresses how strong the balance of benefits and harms is for a preventive service and how certain we are about that balance. A B grade means there is at least moderate certainty that the net benefit is moderate, and therefore the service should be offered. In other words, the benefits are meaningful but not so large or certain as to be considered substantial, so the recommendation still favors offering the service.

This is different from a stronger endorsement that would require a substantial net benefit with high certainty, which would carry a higher-grade recommendation to offer. It’s also different from a recommendation against offering, which occurs when harms outweigh benefits with at least moderate certainty, and from an indication that the evidence is insufficient to judge benefits or harms, which means no clear recommendation. The essential idea is that the service has a positive balance of benefits and harms worth offering, even if the advantage is moderate rather than substantial.