Cost effectiveness of multimodal intraoperative monitoring during spine surgery

Abstract

Debates on the cost-effectiveness of multimodal intraoperative monitoring (IOM) have been going on for more than a decade [5, 7, 10, 11, 18]. One of the prejudices against the effectiveness of IOM was the idea that monitoring techniques can merely document neurological injury, with very little space for intervention. This concept should nowadays be abandoned because, in most of the circumstances, an experienced intraoperative neurophysiologist detects an impending injury to the nervous system in time for corrective measures to be taken. This ultimately results in either complete prevention or limitation of a neurological deficit. There is increasing evidence and general consensus among experts that IOM is valuable in spinal cord monitoring. From case reports to clinical series, authors from different centres worldwide have documented the benefit of IOM to prevent irreversible neurological injury [13, 15]. Yet, in the era of evidence based medicine, we are more and more asked to demonstrate that monitoring “really makes a difference” by performing control studies. However, existing data on the benefit of monitoring are limited to Class IV (most studies based on retrospectively collected data) and Class III (clinical studies with prospective data collection, retrospective studies with clearly reliable data) studies. On the other hand, Class I and II studies (prospective randomized trials) are very unlikely to occur because of both ethical and medico-legal constraints. To design a randomized controlled study would imply to assign some patients to a designated control group where IOM is not used. Those supporting the use of IOM would refuse to randomize patients for such a study because the likelihood of deficit prevention is so high—with currently used IOM techniques—that a controlled study would not be acceptable to most patients and surgeons. Moreover, the adequate sample of patients to design randomized studies far exceeds the case load of a single institution. For example, the power calculations for a prospective randomized trial of evoked potential monitoring for reduction of paraplegia following spine surgery is such that as many as 4,674 patients would be necessary to prove that IOM reduces the incidence of neurological deficit of 50% (from 1 to 0.5%). Similarly, the number of patients for a prospective randomized trial aimed to prove that motor evoked potential (MEP) monitoring is superior to somatosensory evoked potential (SEP) monitoring (remaining incidence of severe injury from 0.5 to 0.1% ) is about 2,934 patients per group [8]. It therefore appears that today it is still valid what Phillips and Park observed in 1990 [14], when they stated that “advocates of most monitoring techniques point to the lack of bad outcomes as proof that their particular technique has value”. From here, one feasible path to increase the evidence of the benefit of IOM is that of performing historical control studies or meta-analyses. Meanwhile, the value of IOM should be proved also from a merely economical perspective, in terms of cost-effectiveness. In this short report, we reviewed some recent data on the rate of neurological complications after different kind of spine and spinal cord surgery. We then analyzed the costs of health care for spinal cord injured patients and, finally, compared these costs with those of IOM.