Figure 3.

Marginal cost-effectiveness ratio (mCER) of high-resolution computed tomography (HRCT) chest screening in relationship to the prevalence of diffuse cystic lung diseases (DCLDs) in patients presenting with an apparent primary spontaneous pneumothorax (PSP). This analysis demonstrates that as the prevalence of DCLDs among patients with an apparent PSP increases, it becomes more cost effective to screen for the presence of DCLDs. By convention, treatment strategies with an mCER of less than $50,000 per quality-adjusted life-year (QALY) gained are considered cost effective. On the basis of that threshold, the strategy for HRCT screening remains cost effective as long as DCLD prevalence among patients presenting with an apparent PSP is greater than 0.01%. Arrow denotes the base case in our analysis.