Mathematical Validation and Credibility of Diagnostic Blocks for Spinal Pain.

BACKGROUND: Diagnostic blocks are used in different ways for the diagnosis of spinal pain, but their validity has not been fully evaluated.

METHODS: Four clinical protocols were analyzed mathematically to determine the probability of correct responses arising by chance. The complement of this probability was adopted as a measure of the credibility of correct responses.

RESULTS: The credibility of responses varied from 50% to 95%, and was determined less by the agents used but more by what information was given to patients and if the agents were fully randomized for each block.

CONCLUSIONS: Randomized, comparative local anesthetic blocks offer a credibility of 75%, but randomized, placebo-controlled blocks provide a credibility of 95%, and are thereby suitable as a criterion standard for diagnostic blocks.