Controlled zygapophysial joint blocks: the travesty of cost-effectiveness

The aim of this study was to develop equations by which the costs could be compared of various models of performing diagnostic blocks for spinal pain.

Algorithms were elaborated describing different strategies for the diagnosis of cervical or lumbar zygapophysial joint pain using placebo-controlled diagnostic blocks, comparative local anaesthetic blocks, or no control blocks, and its treatment with radiofrequency neurotomy. For each step in each algorithm cost functions were applied. Summary equations were derived that allowed the cost of the algorithms to be compared algebraically. A selection of costs were substituted for the unknown variables in the equations in order to illustrate the cost-effectiveness of different algorithms under Australian and US conditions.

The equations indicated that cost-effectiveness was critically dependent on the ratio between the cost of treatment and the cost of a diagnostic block. For cervical zygapophysial joint pain, reimbursements discourage best practice, both in Australia and in the United States, by rendering the use of controlled blocks more expensive than no controls. For lumbar zygapophysial joint pain, controlled blocks are cost-effective under Australian fee schedules, and under some but not all American schedules. In the name of cost-effectiveness, the US fee structure encourages presumptive therapy without regard to diagnosis, but ignores the ethical and logistic consequences of inordinately high failure rates of therapy when a diagnosis is not established using controlled blocks.

Best practice, using placebo-controlled diagnostic blocks before neurosurgical therapy of zygapophysial joint pain, is not encouraged and rewarded in the United States. In Australia it is compensated only in the context of lumbar zygapophysial joint pain. In the interests of short-term financial savings, the US fee structure sacrifices the majority of patients to failed treatment because of lack of proper diagnosis. Clinical absurdity, rather than evidence-based, best practice is encouraged.