A positive incremental net monetary benefit (INMB) indicates what?

• A. The treatment costs more than benefits
• B. The study is inconclusive
• C. The treatment is cost-effective
• D. The treatment is not cost-effective

Answer: (C)

Incremental net monetary benefit is a way to decide if an intervention’s extra health gains are worth the extra costs when those gains are valued at a specific willingness-to-pay per unit of effect. It combines effects and costs into one number: INMB = (ΔEffect × λ) − ΔCost, where ΔEffect is the additional health benefit (like QALYs), λ is the value put on one unit of that benefit, and ΔCost is the extra cost of the intervention.

A positive INMB means the monetized value of the health gains exceeds the additional costs, so the intervention is cost-effective at the chosen threshold. Put simply, at that willingness-to-pay level, you’re getting a net monetary gain from adopting the intervention. This doesn’t require costs to be lower in a raw sense—benefits are being valued monetarily, and a positive result reflects a favorable balance given that value.

For example, if the health gain is worth $50,000 per unit of effect and you gain 0.5 units, that’s $25,000 in benefits; if the extra cost is $18,000, INMB is $7,000, signaling cost-effectiveness at that threshold.