Prevalence of microcephaly in Europe: population based study.
OBJECTIVE
To provide contemporary estimates of the prevalence of microcephaly in Europe, determine if the diagnosis of microcephaly is consistent across Europe, and evaluate whether changes in prevalence would be detected using the current European surveillance performed by EUROCAT (the European Surveillance of Congenital Anomalies).


METHODS
Questionnaire and population based observational study.


METHODS
24 EUROCAT registries covering 570 000 births annually in 15 countries.


METHODS
Cases of microcephaly not associated with a genetic condition among live births, fetal deaths from 20 weeks' gestation, and terminations of pregnancy for fetal anomaly at any gestation.


METHODS
Prevalence of microcephaly (1 Jan 2003-31 Dec 2012) analysed with random effects Poisson regression models to account for heterogeneity across registries.


RESULTS
16 registries responded to the questionnaire, of which 44% (7/16) used the EUROCAT definition of microcephaly (a reduction in the size of the brain with a skull circumference more than 3 SD below the mean for sex, age, and ethnic origin), 19% (3/16) used a 2 SD cut off, 31% (5/16) were reliant on the criteria used by individual clinicians, and one changed criteria between 2003 and 2012. Prevalence of microcephaly in Europe was 1.53 (95% confidence interval 1.16 to 1.96) per 10 000 births, with registries varying from 0.4 (0.2 to 0.7) to 4.3 (3.6 to 5.0) per 10 000 (χ(2)=338, df=23, I(2)=93%). Registries with a 3 SD cut off reported a prevalence of 1.74 per 10 000 (0.86 to 2.93) compared with those with the less stringent 2 SD cut off of 1.21 per 10 000 (0.21 to 2.93). The prevalence of microcephaly would need to increase in one year by over 35% in Europe or by over 300% in a single registry to reach statistical significance (P<0.01).


CONCLUSIONS
EUROCAT could detect increases in the prevalence of microcephaly from the Zika virus of a similar magnitude to those observed in Brazil. Because of the rarity of microcephaly and discrepant diagnostic criteria, however, the smaller increases expected in Europe would probably not be detected. Clear diagnostic criteria for microcephaly must be adopted across Europe.
Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK.
Joan K
JK
Morris
Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK.
Judith
J
Rankin
Paediatric Department, Hospital Lillebaelt, Kolding, Denmark.
Ester
E
Garne
University of Ulster, Newtownabbey, Co Antrim, Northern Ireland, UK.
Maria
M
Loane
University of Ulster, Newtownabbey, Co Antrim, Northern Ireland, UK.
Ruth
R
Greenlees
Division of Medical Genetics, Lausanne, Switzerland.
Marie-Claude
MC
Addor
Public Health Division of Gipuzkoa, Instituto BIO-Donostia, Basque Government, CIBER Epidemiologia y Salud Publica - CIBERESP, Spain.
Larraitz
L
Arriola
Children's Hospital Zagreb, Medical School University of Zagreb, Zagreb, Croatia.
Ingeborg
I
Barisic
University of Groningen, University Medical Centre Groningen, Department of Genetics, Groningen, Netherlands.
Jorieke E H
JE
Bergman
National Public Health and Medical Officer Service, Hungarian Congenital Abnormality Registry, Budapest, Hungary.
Melinda
M
Csaky-Szunyogh
Centro de Estudos e registo de A C, Lisbon, Portugal.
Carlos
C
Dias
University of Leicester, Leicester, UK.
Elizabeth S
ES
Draper
Department of Health Information and Research, Guardamangia, Malta.
Miriam
M
Gatt
INSERM, Paris, France.
Babak
B
Khoshnood
Department of Global Public Health and Primary Care, University of Bergen, and Medical Birth Registry of Norway, Norwegian Institute of Public Health, Bergen, Norway.
Kari
K
Klungsoyr
National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK.
Jennifer J
JJ
Kurinczuk
Health Service Executive, Kilkenny, Republic of Ireland.
Catherine
C
Lynch
Health Service Executive, Dublin, Republic of Ireland.
Robert
R
McDonnell
Provincial Institute for Hygiene, Antwerp, Belgium.
Vera
V
Nelen
IMER Registry, Centre for Clinical and Epidemiological Research, University of Ferrara and Azienda Ospedaliero- Universitaria di Ferrara, Ferrara, Italy.
Amanda J
AJ
Neville
Health Service Executive, Cork, Republic of Ireland.
Mary T
MT
O'Mahony
CNR Institute of Clinical Physiology, Pisa, Italy.
Anna
A
Pierini
Registre des Malformations Congenitales de la Reunion, Saint-Pierre, Reunion.
Hanitra
H
Randrianaivo
Malformation Monitoring Centre Saxony-Anhalt, Medical Faculty Otto-von-Guericke University Magdeburg, Magdeburg, Germany.
Anke
A
Rissmann
Public Health Wales, Swansea, UK.
David
D
Tucker
Institut de Pathologie at de Genetique, Charleroi, Belgium.
Christine
C
Verellen-Dumoulin
University of Groningen, University Medical Centre Groningen, Department of Genetics, Groningen, Netherlands.
Hermien E K
HE
de Walle
University of Southampton and Wessex Clinical Genetics Service, Southampton, UK.
Diana
D
Wellesley
Birth Registry Mainz Model, University Medical Centre of Johannes Gutenberg University, Mainz, Germany.
Awi
A
Wiesel
University of Ulster, Newtownabbey, Co Antrim, Northern Ireland, UK.
Helen
H
Dolk
D005060:Europe / Q000453:epidemiology; D005260:Female; D005313:Fetal Death; D006801:Humans; D008297:Male; D008831:Microcephaly / Q000175:diagnosis* / Q000453:epidemiology*; D011159:Population Surveillance; D011247:Pregnancy; D011296:Prenatal Diagnosis; D015995:Prevalence; D012042:Registries; D012189:Retrospective Studies; D011795:Surveys and Questionnaires