Thank you for taking interest in our systematic review and meta-analysis of the incidence of traumatic brain injury (TBI). A study of this scope that aims to collect all available data on the incidence and prevalence of TBI is certainly a substantial task, and as described in our methods, we had defined search criteria to aid in this process.

We reviewed our criteria to determine why the articles that you cited were not included. The article by Vafaee et al. is published in a journal that is neither indexed in MEDLINE or EMBASE, the two main recommended databases used for systematic reviews; as a result, was not found in our search. The article by Agakhani et al. was excluded because it did not report an estimate of incidence or prevalence. The article by Rahimi-Movaghar et al. met our initial search criteria but was not included in our study because, at the time, it was not available through our interlibrary loan program. We were now able to obtain a copy of the article and reanalysis showed a small decrease in the estimate of incidence proportion from 295 per 100,000 (95% confidence interval, 274-317) to 214 per 100,000 (95% confidence interval, 160-286).

We conducted our systematic review according to established PRISMA guidelines and attempted to be as comprehensive as possible, although there is always the possibility that articles published in lower impact journals that are not indexed in MEDLINE or EMBASE or that are not typically held by libraries outside of the country of interest will be missed. Our search criteria only revealed one article originating from Asia and now, one from West Asia. This lack of representation of TBI epidemiology studies out of Asia is discussed as a limitation in our publication. We appreciate that you have further brought this to our attention as it again highlights the difficulty in defining a true incidence of TBI, a condition that is considered a “silent epidemic” because of difficulties in data collection, underreporting, and varied diagnostic definitions. Thus the incidence of TBI may be higher than what is reported in the literature (although the addition of the Rahimi-Movaghar slightly decreased the estimate), but we are confident that with continued awareness there will be increased support for prevention and treatment strategies for TBI.