Global Biomedical R&D Expenditures

To the Editor: In their Perspective article, Chakma et al. (Jan. 2 issue)¹ report estimates for global trends in expenditures on health research and development (R&D). Their analysis is questionable. First, expenditure data should be deflated in the national currency and then compared with the use of an appropriate exchange rate for one base year. The authors' approach overestimates growth in countries with relative currency appreciation. Second, the standard approach is to deflate expenditure data with the use of the implicit gross domestic product (GDP) price index, not the National Institutes of Health R&D price index, which flatters countries with . . .