We would like to thank Dr Hueto and his colleagues for their interest in our article on the situation of spirometry of Spain, and for the comparative analysis they make with their own survey, conducted in 2012,1 on the quality of spirometry in specialized care centers in the public health sector of their region. As they mention, when both surveys are compared, the results vary considerably. Moreover, Hueto et al. suggest that the methodology section of our 3E inter-regional study2 does not give information on the types of centers polled, nor on the specialty being evaluated. They also say that there is no mention of the criteria used in the 3E study to determine the quality of the bronchodilator tests and the spirometries. We would like to make 3 points in this regard:

• First, it is no surprise that our results are different from those published by Dr Hueto and his colleagues.1,3 Different results often emerge if the same problem is examined using different methodologies. Dr Hueto and his co-workers evaluated the use of spirometry in public hospitals with specialist care units. In contrast, as we explain in the methodology sections of the principal research article4 and the subsequent studies,2,5 the 3E study included all healthcare centers seeing adult patients with respiratory disease. In other words, our aim was not give an overview of the situation in public hospitals, but rather to give an idea of the wider reality of how this diagnostic technique is applied in Spain.

• Second, our spirometry and bronchodilator test quality criteria are explicitly detailed in the article they cite,2 and in another subsequent publication.5 As we explain in the methodology section of these papers, we used 8 quality criteria for spirometries and 5 for the bronchodilator tests. It is important to remember that the 3E study was a telephone survey, not a clinical audit. Accordingly, we selected quality criteria which could be measured with this method. We did not evaluate the technical quality of the spirometries, but we did refer to previous experiences reported in Spain.6

• Lastly, it is important to remember that many studies and geographical epidemiology reviews have underlined the dangers of using the micro to interpret the macro,7 particularly in a study with the inherent “noise” typical of an anonymous, third-person telephone survey. We must not forget that any interpretation of a health survey must consider the overall context. In view of the inherent features of the methodology used, such as sample variability, some surprising results may be expected. The solution in this case is to complete the picture by performing further studies from other perspectives or using different methods. For this reason, Dr Hueto's letter is particularly important, since it complements our data and attempts to provide a better understanding of the overall status of spirometry in Spain. We are sure that together these data can improve the follow-up and implementation of the National COPD Strategy in Spain.