The strategy for implementing a post-introduction observation system was based on the recommendations put forward by a technical group from the Galician Health Technology Assessment Agency in consensus with a working group made up of 11 national HTA experts. At a first work session, the technical group established the fundamental requirements for implementing a post-introduction observation system, and using a consensus-based approach, selected the principal areas to be covered by the outcome indicators, along with the different aspects that could be deemed relevant within each area. For the purpose, account was taken, on the one hand, of the results of the systematic review, and on the other, of past experience of post-introduction observation gained in Galicia. As a result of this first meeting, the members of the technical group independently drew up a series of outcome indicators. These indicators were presented at a second work session of the technical group, and those that were deemed relevant for the study objectives were then selected on a consensus basis. Selection of the outcome indicators was based on the following criteria: 1) basic aspect for evaluating deviations in the use/results of new technologies, which could lead to important repercussions for the health of the population or the health system; and, 2) feasibility of the measure. Following this meeting, the first list of outcome indicators was drawn up, with definitions of the various terms and the pertinent explanations.

These proposed indicators were sent by e-mail to the working group for its review, comments, suggested amendments or proposals for additional indicators. In line with these comments, the methodology was updated and the definitive indicators agreed.