American Board of Internal Medicine (ABIM) Certification Practice Exam

A significant decrease in what is considered meaningful for follow-up in syphilis treatment?

1. A twofold decrease in RPR titer

2. A fourfold decrease in RPR titer

3. A sixfold decrease in VDRL titer

4. No specific guideline on decrease

The correct answer is: A fourfold decrease in RPR titer

A fourfold decrease in the Rapid Plasma Reagin (RPR) titer is considered meaningful for follow-up in syphilis treatment because it indicates an adequate response to therapy. In the context of syphilis, especially during follow-up after treatment, a fourfold reduction suggests effective treatment, as the immune system is responding appropriately by decreasing the levels of antibodies. This guideline is based on the standard practice established in syphilis management protocols, where a fourfold decrease is seen as a benchmark that correlates with a decreased disease activity or successful treatment outcome. A twofold decrease may not be sufficient to confirm effective treatment, as some patients may show minor fluctuations in titers without significantly signaling treatment success. A sixfold decrease in VDRL titer is less commonly referenced, making the fourfold reduction in RPR titer the more standard reference point. Additionally, the absence of specific guidelines on the decrease does not apply, since the fourfold decrease is well established in clinical practice for follow-up evaluations post-syphilis treatment.