Atlas of Variations in Medical Practice in Spain: the Spanish National Health Service under scrutiny.

Early in the 2000s, a countrywide health services research initiative was launched under the acronym of Atlas VPM: Atlas of Variations in Medical Practice in the Spanish National Health System. This initiative aimed at describing systematic and unwarranted variations in medical practice at geographic level-building upon the seminal experience of the Dartmouth Atlas of Health Care. The paper aims at explaining the Spanish Atlas experience, built upon the pioneer Dartmouth inspiration. A few selected examples will be used along the following sections to illustrate the outlined conceptual framework, the different factors that may affect variation, and some methodological challenges.