Fig. 2

Tornado diagram of one-way sensitivity analysis. The figure depicts the influence of the variation of each parameter on the ICERs between A routine clinical physical examination and cfEBV DNA-guided MRI + CT + BS in patients with stage I NPC; cfEBV DNA-guided MRI + CT + BS and cfEBV DNA-guided PET/CT in patients with stage B II, C III, and D IV NPC. The parameters accounting for the top 10 uncertainties in each comparison are displayed. The blue bars and red bars illustrate the ICERs that are greater and less than the base-case ICERs, respectively. The orange bars indicate that the ICERs go across the willingness-to-pay threshold, leading to a switch of the most cost-effective strategy. The numbers on both sides of the bars indicate the range of each parameter used in the sensitivity analysis. The solid and dashed lines represent the ICERs in the base-case analysis and the willingness-to-pay threshold of $100,000 per quality-adjusted life-year, respectively. Abbreviations: BS, bone scintigraphy; cfEBV, cell-free Epstein-Barr virus; CT, computed tomography; DM, distant metastasis; ICER, incremental cost-effectiveness ratio; LR, local relapse; MRI, magnetic resonance imaging; NPC, nasopharyngeal carcinoma; PET/CT, positron emission tomography/computed tomography; RR, regional relapse; WTP, willingness-to-pay