What is the post-test probability for cervical myelopathy when 3/5 or 4/5 CPR findings are present?

• A. 60-70%
• B. 80-90%
• C. 99-100%
• D. 94-99%

Answer: (D)

Multiple positive findings on a clinical prediction rule dramatically raise the likelihood of disease. For cervical myelopathy, the five-item CPR shows that having three or four positive findings pushes the post-test probability into the near-certain range. Specifically, 3/5 or 4/5 positive findings yield a post-test probability of about 94–99%. This reflects how the combination of signs increases diagnostic certainty far more than a single finding would. The ranges lower than this (60–70% or 80–90%) or the 99–100% end aren’t supported by the validation data for this rule, making 94–99% the best summary of the evidence for 3/5 or 4/5 positives.