title: Microtia-anotia: a global review of prevalence rates.
abstract: BACKGROUND
  There are few published studies on microtia-anotia frequency.
  
  
  METHODS
  Using data from birth defects surveillance programs around the world, we conducted a systematic review on the frequency of microtia-anotia to further explore the differences in prevalence across countries. Ninety-two birth defects surveillance programs were evaluated with a total of 8917 cases of microtia-anotia. We computed the prevalence per 10,000 births for each surveillance program for total cases of microtia-anotia (microtia types I to IV), microtia (types I to III), and anotia (type IV). Prevalence ratios were calculated by large geographic areas, race/ethnicity, and by surveillance methodologies.
  
  
  RESULTS
  The overall prevalences were: microtia-anotia, 2.06 (confidence interval [CI], 2.02-2.10); microtia, 1.55 (CI, 1.50-1.60); and anotia 0.36 (CI, 0.34-0.38). Higher prevalences were observed for the Americas, Northern Europe and Asia, among Hispanics and Asians, and among active ascertainment and hospital-based surveillance programs.
  
  
  CONCLUSIONS
  We observed marked variation in the prevalence of microtia-anotia across surveillance programs and within countries. These results must be interpreted cautiously as this variability may be explained mainly by differences in surveillance methods. However, given the magnitude of some of the differences, other factors may also be involved. This study contributes to the knowledge of the prevalence of microtia-anotia by providing a critical analysis of the existing data. In addition, it supports the need for a coding system that allows complete phenotype characterization of microtia-anotia, including severity and laterality, as well as for further studies on the variation of its frequency related to race and ethnicity.
authors.affiliation: Division of Craniofacial Medicine, Department of Pediatrics, University of Washington, Seattle, USA. daniela.luquetti@seattlechildrens.org
authors.forename: Daniela Varela
authors.initials: DV
authors.lastname: Luquetti
authors.forename: Emanuele
authors.initials: E
authors.lastname: Leoncini
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Mastroiacovo
mesh_terms: D000013:Congenital Abnormalities / Q000453:epidemiology*; D065817:Congenital Microtia; D016208:Databases, Factual; D004423:Ear / Q000002:abnormalities; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D012720:Severity of Illness Index