Cost-effectiveness of Magnetic Resonance Imaging in Cervical Clearance of Obtunded Blunt Trauma After a Normal Computed Tomographic Finding

Abstract

Importance: Magnetic resonance imaging (MRI) continues to be performed for cervical clearance of obtunded blunt trauma, despite poor evidence regarding its utility after a normal computed tomographic (CT) finding.

Objective: To evaluate the utility and cost-effectiveness of MRI vs no follow-up after a normal cervical CT finding in patients with obtunded blunt trauma.

Design, setting and participants: This cost-effectiveness analysis evaluated an average patient aged 40 years with blunt trauma from an institutional practice. The analysis used a Markov decision model over a lifetime horizon from a societal perspective with variables from systematic reviews and meta-analyses and reimbursement rates from the Centers for Medicare & Medicaid Services, National Spinal Cord Injury Database, and other large published studies. Data were collected from the most recent literature available.

Interventions: No follow-up vs MRI follow-up after a normal cervical CT finding.

Results: In the base case of a 40-year-old patient, the cost of MRI follow-up was $14 185 with a health benefit of 24.02 quality-adjusted life-years (QALY); the cost of no follow-up was $1059 with a health benefit of 24.11 QALY, and thus no follow-up was the dominant strategy. Probabilistic sensitivity analysis showed no follow-up to be the better strategy in all 10 000 iterations. No follow-up was the better strategy when the negative predictive value of the initial CT was relatively high (>98%) or the risk of an injury treated with a cervical collar turning into a permanent neurologic deficit was higher than 25% or when the risk of a missed injury turning into a neurologic deficit was less than 58%. The sensitivity and specificity of MRI were varied simultaneously in a 2-way sensitivity analysis, and no follow-up remained the optimal strategy.

Conclusions and relevance: Magnetic resonance imaging had a lower health benefit and a higher cost compared with no follow-up after a normal CT finding in patients with obtunded blunt trauma to the cervical spine, a finding that does not support the use of MRI in this group of patients. The conclusion is robust in sensitivity analyses varying key variables in the model. More literature on these key variables is needed before MRI can be considered to be beneficial in the evaluation of obtunded blunt trauma.

Figure 1.. Simplified Flowchart of the Decision Tree

CS indicates cervical spine; CT, computed tomography; and MRI, magnetic resonance imaging.

Figure 2.. Incremental Cost-effectiveness for Magnetic Resonance Imaging (MRI) vs No Follow-up

The scatterplot depicts 10 000 iterations in the probabilistic sensitivity analysis. No follow-up is the better strategy in all iterations. The shaded area corresponds to cases in which no follow-up is a better strategy than MRI. QALY indicates quality-adjusted life-year; WTP, willingness to pay.

Figure 3.. Two-Way Sensitivity Analysis Varying the Negative Predictive Value (NPV) of the Initial Computed Tomographic (CT) Scan and the Percentage of Missed Unstable Injuries Turning Into Spinal Cord Injuries

The colors on the graph represent the areas where the corresponding strategy is better (higher net monetary benefit defined as utility × willingness to pay – cost, where willingness to pay is $100 000.00). MRI indicates magnetic resonance imaging.

Figure 4.. Two-Way Sensitivity Analysis Varying the Negative Predictive Value (NPV) of the Initial Computed Tomographic (CT) Scan and the Percentage of Collared Unstable Injuries Turning Into Spinal Cord Injuries

The colors on the graph represent the areas where the corresponding strategy is better (higher net monetary benefit defined as utility × willingness to pay – cost, where willingness to pay is $100 000.00). MRI indicates magnetic resonance imaging.