Thank you for sharing insights and concerns regarding the status of cost-of-illness (COI) studies within the realm of health economics and outcomes research. We acknowledge the limitations of such studies; however, because they are not economic evaluations, we did not discuss the overall concern raised by the reader in our article on the COI of head and neck cancer (HNC). Nevertheless, the critique of COI studies, which we assume is well-known by the readers of Value in Health, underscores the need to address this and provide justifications.