Notes for the reader
These tables summarize findings from the International Perinatal Database of Typical Orofacial Clefts (IPDTOC), which is the first step of the International Database of Craniofacial Anomalies (IDCFA). Data are collected from participating registries and processed at the International Centre of Birth Defects (ICBD).
Information for each country
For each country, the following data is provided:
- Number of cases by type and total rates, by register
- Distribution by type: isolated, associated with other major malformations, syndromes by register
- Total cases, by type and by set of registries
- Number of cases by set of registries
- Rates with 95% confidence interval (CI)
- Proportion of Termination of Pregnancy (ToP)
- Sex ratio (expressed as M/M+F) with 95% CI
- Births
- ToP
- Median and interquartile range for birth weigth (only for live and still births)
- Proportion of live and stillbirths under 2.500 grams
- Median and interquartile range for gestational age (only for live and stillbirths)
- Proportion of live and stillbirths under 37 weeks of gestation
- Proportion of live and stillbirths with IUGR (< 10° centile of weigth for gestational age)
- Rate of twin deliveries = twins deliveries / twins deliveries + singleton deliveries
- List of syndromes
- Isolated cases, by type and by set of registries
- Number of cases by set of registries
- Rates with 95% confidence interval (CI)
- Proportion of Termination of Pregnancy (ToP)
- Sex ratio (expressed as M/M+F) with 95% CI
- Births
- ToP
- Median and interquartile range for birth weigth (only for live and still births)
- Proportion of live and stillbirths under 2.500 grams
- Median and interquartile range for gestational age (only for live and stillbirths)
- Proportion of live and stillbirths under 37 weeks of gestation
- Proportion of live and stillbirths with IUGR (< 10° centile of weigth for gestational age)
- Rate of twin deliveries = twins deliveries / twins deliveries + singleton deliveries
Data Collection
Participating registries collect data from maternity hospitals on affected fetuses (in case of termination of pregnancy) or affected newborns. For more information on specific registries please refer to:
(a)www.icbd.org
(b)www.eurocat.ulster.ac.uk
(c)www.nbdpn.org
Data are electronically transmitted to ICBD as a file (usually in Excel table format) containing case records (one record per each affected subject). For each submitted case, registries should send all information available to them, which must include a minimum set of information with the following data:
- Unique ID
- Type of cleft: coded with any coding system, preferably ICD 9 or ICD 10 and extensions (eg, ICD9-BPA), plus, if available, verbatim description of malformations.
- Associated anomalies: coded with any coding system, preferably ICD 9 or ICD 10 and extensions (eg, ICD9-BPA), plus, if available, verbatim description of malformations.
- Final clinical diagnosis: Isolated, with other malformations, syndrome. This is a suggested field to be added to your database. ICBD staff will review or create the field.
- Month and year of birth;
- Birth outcome: Livebirth, Stillbirth, Termination of pregnancy.
- Sex; birthweight, gestational age
- Twinning status: if available also include information on the cotwin (sex and malformation if any);
- Maternal age
Each registry has decided the starting year (2000, 2001 or 2002) and the update frequency (every six months or yearly).
All cases are then reviewed at ICBD.
- Potentially inconsistent data are flagged (e.g.: outliers, major discrepancy between birth-weight and gestational age) and a request is sent to the registry for clarification.
- Cases with two codes (orofacial anomaly plus any other anomaly) are evaluated and potentially recoded as:
- (a) multimalformed infant : two or more “major” and “unrelated” anomalies (more specific information are available on http://www.icbd.org)
- syndromic infant: two or more anomalies with a diagnosis of a specific syndrome
In all cases of syndromes ICBD asks the registry to provide some “evidence” of the diagnosis, such as : - clinical only, made by physician who is not a clinical geneticist
- clinical only, made by a clinical geneticist
- clinical and laboratory confirmed (eg, cytogenetic or molecular testing)
- Cases with a Pierre Robin Anomaly are reviewed, and all cases with cleft palate and micrognathia are considered Pierre Robin Anomaly
- Cases of orofacial clefts with associated features of holoprosencephaly are not included in these tables
- Cases with a diagnosis of syndrome will be analyzed separately at a future time when a relevant number is available
Definitions
Total cases = isolated (Iso) + multimalformed (MMI) + syndromic cases (Syndr)
Small for gestational age = birth weight under the 10° percentile for gestational age*
*As determined by tables produced by (Michael S. Kramer, Robert W. Platt, Shi Wu Wen, K.S. Joseph, Alexander Allen, Michael Abrahamowicz, Béatrice Blondel, Gérard Bréart, A New and Improved Population-Based Canadian Reference for Birth Weight for Gestational Age, PEDIATRICS Vol.108 No.2 August 2001)
Interpretation of data
The variation among registries of the proportion of isolated cases is not likely due to coding because the same staff at ICBD reviews all cases and classifies them as isolated, multiples (MMI) and syndromic.
The only source of spurious variability is than the ascertainment bias
Please note that termination of pregnancies (ToP) are forbidden by law in the following countries:
- All South American Countries
- Ireland
- Malta
- Mexico
- United Arab Emirates
and are not reported in the following registries
- Japan
- South Africa
- Ukraine
Interpretation of cumulative data that include ToP should take into consideration these exceptions as well as the variability of ascertainment of anomalies among ToP.
Geographic variation in the tables must be interpreted with great caution because of the differences between registries.
It is best to always consider these data as preliminary. Changes may be introduced at any time because of :
- better diagnostic definition obtained by ICBD (e.g.: a syndromic case may be considered an MMI or vice versa)
- better definition of the orofacial anomaly (e.g.: bilateral case may be recoded as unilateral or vice versa)
Thus, the data presented here are the best available, based on cases evaluated by the registry alone or in collaboration with the central coordinating office (ICBD).
Terms and conditions
- Contributing registries may ask for specific analysis of data to ICBD
- Data cannot be used without written permission of the registries involved and the coordinating office (ICBD)