[Quaternary prevention in primary care: a necessity for the Brazilian Unified National Health System].

In 2003, the World Organization of National Colleges, Academies, and Academic Associations of General Practitioners/Family Physicians (WONCA) proposed a concept (that had previously received relatively little discussion) aiming to protect patients from unnecessary medical interventions and to prevent iatrogenicity: quaternary prevention. In times of intense social medicalization, particularly in Brazil due to the expansion of health care through the Family Health Strategy, iatrogenicity has become a highly relevant issue for both public health and the Unified National Health System (SUS). This article presents the concept of quaternary prevention and discusses and frames its relevance in light of three common situations in medical care with potentially iatrogenic results: excessive screening, complementary tests, and medicalization of risk factors. We propose the inclusion and discussion of this concept in the SUS, especially in primary care.