Objective: To estimate the cost-effectiveness of CT for detecting brain lesions in patients with lung cancer without clinical evidence of metastases.
Design: Decision analysis model comparing two different strategies for detecting brain metastases: brain CT routinely (CT-first) or brain CT only when patients develop neurologic signs and/or symptoms (CT-deferred).
Patients: Hypothetical cohort of patients with lung cancer with an unremarkable screening clinical evaluation for metastases.
Measurements: Net costs are calculated as the difference in costs between the two limbs of the decision tree. Net benefits are expressed as the difference in calculated years of life expectancy between the two strategies. Net costs are divided by net benefits, yielding the marginal cost per quality adjusted year of added life expectancy (C/QALY) for the CT-first strategy.
Results: In the baseline analysis, the C/QALY for the CT-first strategy is about $70,000. Improving the clinical evaluation as a screen for detecting brain metastases markedly increases the C/QALY. Increasing the cost of brain CT magnifies this effect. More effective treatment for asymptomatic brain metastases and better accuracy of CT for identifying resectable and unresectable brain metastases lower C/QALY.
Conclusions: Although a threshold cost-effectiveness has not been defined for identifying "cost-effective" diagnostic procedures, the marginal C/QALY of the CT-first strategy is substantially higher than many accepted medical interventions. At current costs, the routine use of brain CT is not warranted in patients with lung cancer who have normal findings on a standardized clinical evaluation for metastases.