Figure 1. "The Break-even Point" (for a drug that reduces mortality by 20%).

Triangle A. If 100,000 patients are destined to die from a disease, a drug that reduces death rates by 20% (relative risk reduction [RRR] = 0.20) will save 16,000 lives (A1) if delivered to 80% of eligible patients. Increasing delivery to 100% would save 4,000 more lives (A2). To save as many lives with without improving upon the delivery rate of 80% (A3), the RRR of the drug must be increased to at least 25% (‘break-even point").

Triangle B. Delivering the drug to only 60% of patients would save only 12,000 lives (B1), and improving delivery to 100% would save 8,000 additional lives. To save 8,000 additional lives without improving upon the delivery rate of 60% (B2), the RRR of the drug must be increased to at least 33.3% ("break-even point"). Developing a more efficacious drug is more beneficial than improving access only if the new relative risk reduction (RRR) exceeds the existing RRR divided by the proportion of the population exposed to treatment. The complete nomogram from which the figure derives is provided by the Annals in an online appendix available at http://www.annfammed.org/cgi/content/full/3/6/545/DC1.