[Six-minute walk test: necessary in order to understand patient limitations].

increase our understanding of this topic, it would be desirable to have a single equation. My suggestion would be that, at some future date, those two groups of authors combine their data in order to produce such an equation. Despite the discrepancies between the two studies cited above, we congratulate both groups of authors for taking the initiative to research a topic of great interest to pulmonologists: country-specific 6MWD reference values. Dourado was involved in developing the first reference equation related to the use of the 6MWT in Brazil,(8) and Pereira was among those responsible for establishing spirometric reference values for adults in our country.(11) To our pleasant surprise, Etemadinezhad & Alizadeh,(12) in this same issue, have published spirometric reference values for Iran. It is now imperative that we employ the 6MWD predictive equations proposed here,(9,10) not only for expressing the distance covered by our patients but also for determining the physical limitation of those patients in values relative to those of the general population of Brazil.