Candidate for the Lee B. Lusted Student Prize Competition
Method: A decision analytic model was developed to estimate quality-adjusted-life (QALY) and costs associated with biopsy and advanced imaging (such as MR spectroscopy) in differentiating between malignant and benign STMs for the first five years after diagnosis. The model incorporated prevalence of malignant and benign STMs at the community level, the performance characteristics of the imaging modality of choice, 1-5 year overall survival rate for the different stages at the time of diagnosis, and costs and effectiveness associated with each strategy. A discount rate of 3% was considered. An incremental cost per QALY gained was compared between two strategies. One-way sensitivity analysis was performed to evaluate the stability of the model to change in the clinically-plausible range for all the variables. Threshold analysis was used to determine the performance characteristic of the imaging tool, which could justify its utilization regarding costs and effectiveness instead of biopsy.
Result:
Considering a malignancy prevalence of 0.01 and sensitivity and specificity of 95% and 82% for the imaging modality, we ran a Monte Carlo micro-stimulation model for 10000 times. The results demonstrated that biopsy is the dominated strategy and less cost effective strategy in comparison to advanced imaging tool. The incremental cost per quality for biopsy was $114700. Threshold analysis revealed that only an imaging tool with sensitivity lower than 83% and specificity lower than 75% justifies not using it. One-way sensitivity analysis showed the model is stable to change in a clinically plausible range for the other variables.
Conclusion: For the work-up of new STMs, advanced imaging is a cost-effective non-invasive alternative to biopsy. Benign STMs present to Orthopaedic clinics 100 times more commonly than malignant STMs and are often referred for biopsy. Decision analysis proves the value of advanced imaging as the initial choice for work-up instead of biopsy.