Report and Estimated Defect Prevalence Estimates (per 10,000 live births)
Defect Reports Report Prevalence (95%CI) PPV NPV Estimated Defects Defect Prevalence (95%CI)
Cardiovascular
  Aortic valve stenosis 8 1.4 (0.6,2.8) NA
  Atrial septal defect 888 156.6 (146.5,167.3) NA
  Atrioventricular septal defect 41 7.2 (5.2,9.8) NA
  Coarctation of the aorta 30 5.3 (3.6,7.6) NA
  Common truncus 14 2.5 (1.3,4.1) NA
  Double outlet right ventricle 12 2.1 (1.1,3.7) NA
  Ebstein anomaly 7 1.2 (0.5,2.5) NA
  Hypoplastic left heart syndrome 12 2.1 (1.1,3.7) NA
  Inerrupted aortic arch 25 4.4 (2.9,6.5) NA
  Pulmonary valve atresia and stenosis 81 14.3 (11.3,17.8) NA
  Single ventricle 9 1.6 (0.7,3.0) NA
  Teratology of fallot 35 6.2 (4.3,8.6) NA
  Total anomalous pulmonary venous sonnection 10 1.8 (0.8,3.2) NA
  Transposition of the great arteries 28 4.9 (3.3,7.1) NA
  Tricuspid valve atresia and stenosis 6 1.1 (0.4,2.3) NA
  Ventricular septal defect 574 101.2 (93.1,109.9) NA
Central Nervous System
  Anencephalus 14 2.5 (1.3,4.1) 0.3929 1.0000 5.5 1.0 (0.4,2.1)
  Spina bifida without anencephalus 21 3.7 (2.3,5.7) 0.5946 0.9999 16.0 2.8 (1.6,4.4)
  Encephalocele 18 3.2 (1.9,5.0) 0.3778 1.0000 7.1 1.3 (0.6,2.5)
  Holoprosencephaly 53 9.3 (7.0,12.2) NA
Chromosomal
  Deletion 22 q11 - - NA
  Trisomy 13 7 1.2 (0.5,2.5) 0.5000 1.0000 3.5 0.6 (0.2,1.5)
  Trisomy 18 12 2.1 (1.1,3.7) 0.5833 1.0000 7.0 1.2 (0.5,2.5)
  Trisomy 21 (Down syndrome) 91 16.1 (12.9,19.7) 0.8182 0.9999 80.0 14.1 (11.2,17.4)
  Turner syndrome* - - NA
Ear
  Anotia / microtia 20 3.5 (2.2,5.4) NA
Eye
  Anophthalmia / microphthalmia 8 1.4 (0.6,2.8) NA
  Congenital cataract 29 5.1 (3.4,7.3) NA
Gastrointestinal
  Biliary atresia 13 2.3 (1.2,3.9) NA
  Esophageal atresia / tracheoesophageal fistula 15 2.6 (1.5,4.4) NA
  Rectal and large intestinal atresia / stenosis 59 10.4 (7.9,13.4) NA
  Small intestinal atresia / stenosis 42 7.4 (5.3,10.0) NA
Genitourinary
  Bladder exstrophy - - NA
  Cloacal exstrophy - - NA
  Congenital posterior urethral valves 42 7.4 (5.3,10.0) NA
  Hypospadias** 320 109.3 (97.6,121.9) 0.8618 0.9996 286.0 97.7 (86.7,109.3)
  Renal agenesis / hypoplasia 44 7.8 (5.6,10.4) NA
Musculoskeletal
  Clubfoot 201 35.5 (30.7,40.7) NA
  Craniosynostosis - - NA
  Diaphragmatic hernia 33 5.8 (4.0,8.2) 0.7083 0.9999 26.4 4.6 (3.1,6.7)
  Gastroschisis 22 3.9 (2.4,5.9) 0.6174 1.0000 16.2 2.9 (1.7,4.6)
  Limb deficiencies 67 11.8 (9.2,15.0) NA
  Omphalocele 79 13.9 (11.0,17.4) 0.1856 1.0000 14.8 2.6 (1.5,4.1)
Orofacial
  Choanal atresia 17 3.0 (1.7,4.8) NA
  Cleft lip with celft palate 44 7.8 (5.6,10.4) 0.6600 1.0000 29.7 5.2 (3.6,7.3)
  Cleft lip alone 23 4.1 (2.6,6.1) 0.3913 1.0000 10.6 1.9 (1.0,3.2)
  Cleft palate alone 80 14.1 (11.2,17.6) 0.5610 0.9998 57.3 10.1 (7.8,13.0)
Ref: NA = Information not available as of publication; ‘-’ = supressed for cell counts <6; 95% CI = 95% Confidence Interval; g = grams, PPV = Positive Predictive Value; NPV = Negative Predictive value

*per 10,000 live female births

**per 10,000 live male births

Note: The Alaska Birth Defects Registry (ABDR) was established and operates under Alaska statute 7 AAC 27.012. Statue allows reports to by age six years of a child. This report includes defects reported before the 3rd birthday.

Column descriptions:
Defect = The Nationally reportable birth defect grouping name.
Reports = Unless otherwise noted, the number of unique reports of defect received by ABDR during the specified birth year(s). Each report represents a unique child with specified defect.
Report Prevalence (95% CI) = The number of reported defects divided by the number of Alaska resident in-state births (Children can be reported multiple times. they are counted only once for each condition).
PPV = The probability of being defect positive given being reported for the defect.
NPV = The probability of being defect negative given not being reported for the defect.
Estimated Defects = The estimated number of defects based on the report prevalence, PPV, and 1-NPV.
Defect Prevalence (95% CI) = The estimated defect prevalence calculated using a Bayesian approach based on the reported prevalence, PPV and 1-NPV (see formula below).

*Through medical records review and case confirmation of a random sample of reported cases, the defect prevalence is calculated as:

\[PPV (Positive Predictive Value) = p(defect)|report)\] \[NPV (Negative Predictive Value) = p(\overline{defect}|\overline{report})]\]

\[p(defect) \approx [p(report)\cdot PPV]+[p(\overline{report})\cdot 1-NPV)]\]

Defect prevalence estimates are a more accurate estimation of the actual diagnosed prevelance of birth defects compared to the reported prevelance estimates in Alaska. ABDR obtains reports from medical providers using International Classification of Disease (ICD) codes that are extracted from individual systems which when aggregated may not reflect true diagnostics. Caution should be used when interpreting and comparing the reported prevalence estimates with national estimates.

**Condition Notes:**
Cleft Lip (CL), Cleft Palate (CP), and Cleft Lip and Palate (CLP) are coded to be mutually exclusive groups.Because an individual can be reported multiple times and for any condition, this coding ensures that for these cleft conditions the classifications conform to the expectation of being mutually exclusive.

Hypospadias is restricted to male births (N = 29281).
Turner Syndrome is restricted to female births (N = 27416).

Resources:
National Birth Defects Prevention Network
Centers for Diesase Control and Prevention

Contact
Alaska Birth Defects Registry (ABDR)
3601 C Street, Suite 358
Anchorage, AK 99503
(907) 269-3400 phone
(907) 754-3529 fax
hssbirthdefreg@alaska.gov

Updated: September 1, 2017
Code source: R:\ABDR\Analysis_New\Published Data\Prevalence09.13.Rmd