A philosophical foundation for diagnostic blocks, with criteria for their validation.
BACKGROUND
In the absence of a suitable reference standard, diagnostic local anesthetic blocks cannot be validated in the manner conventionally used for diagnostic tests. Consequently, diagnostic blocks are vulnerable to criticism for lacking validity, or being "not proven."


METHODS
Philosophical essay.


METHODS
Inspired by the "viewpoints" proposed by Bradford Hill for testing cause and effect in epidemiology, a set of axiomatic criteria was developed with which the validity of diagnostic blocks could be assessed.


RESULTS
Eight criteria were established: plausibility, experiment, target-specificity, effect, duration, consistency, control, and replication. Applying weighted scores to these criteria produces a metric by which the validity of a particular diagnostic block can be quantified.


CONCLUSIONS
The eight criteria provide an axiomatic, philosophical basis for diagnostic blocks in general, and serve to show what empirical evidence needs to be gathered in order to validate a particular block. The associated metric allows the scientific evidence for different blocks to be quantified and compared.
Continental Anesthesia, Oak Brook, Illinois, USA.
Andrew
A
Engel
John
J
MacVicar
Nikolai
N
Bogduk
D000465:Algorithms; D006801:Humans; D009407:Nerve Block / Q000379:methods / Q000592:standards*; D059408:Pain Management / Q000379:methods / Q000592:standards; D010147:Pain Measurement / Q000379:methods / Q000592:standards*; D010686:Philosophy, Medical; D016032:Randomized Controlled Trials as Topic / Q000592:standards
Block; Diagnostic; Local Anesthetic; Validity