Background

Transposition of the great arteries (TGA) is a birth defect of the heart where the aorta and pulmonary arteries are transposed or reversed so that the aorta arises from the right ventricle and the pulmonary artery arise from the left ventricle. There are two forms of TGA, dextro and levo. Dextro (D-TGA) is more common and occurs when the aorta is to the right and in front of the pulmonary artery. [1] The reversal of the arteries results in oxygen-poor blood being pumped back out into the body and oxygen-rich blood being sent back into the lungs. [2] TGA may be diagnosed before birth by ultrasound, or after birth typically within a few hours or days by physical examination, pulse oximetry, or echocardiogram. [3] Symptoms can include cyanosis (blue skin tone), respiratory distress, poor weight gain, and lack of appetite. [4] Emergency procedures to stabilize newborns with TGA include medications (prostaglandin) and balloon atrial septostomy (a catheterization procedure to allow increased mixing of oxygenated blood to the right ventricle). A common surgical treatment, typically done within the first month of life, is the arterial switch procedure where the aorta and pulmonary artery are switched back to their correct position. [1] Because an infant with transposition of the great arteries may need these procedures soon after birth, this defect is considered a critical congenital heart defect.


Epidemiology

Alaska Birth Defects Registry (ABDR) registers birth defects as reported from health care providers using International Classification of Disease (ICD) billing codes. The use of these ICD codes can lead to misclassification of diagnosed conditions. Prior to this report, all prevalence estimates were based on the number of unique children reported to ABDR with an ICD code representing a specified condition regardless of case confirmation status.

The estimates in this report were derived by conducting medical record review and case confirmation of a random sample of cases of the condition reported to ABDR. The confirmation probability from the sample was used to develop informed estimates of the actual diagnosed defect prevalence. See Defect prevalence calculation.

For explanations of table columns see Column descriptions.

Prevalence

Transportation of the great arteries occurs in about 2.9 out of every 10,000 live births in the United States. This results in about 1,153 babies diagnosed with Transportation of the great arteries nationally each year.[1]

In Alaska, during 2007-2017, the prevalence of Transportation of the great arteries was 2.4 per 10,000 live births.
Reports Defects Births Prevalence (95% CI)
Total 47 29.5 123630 2.4 (1.6, 3.4)
Notes: 95% CI = 95% Confidence Interval

Trend

Prevalence per 10,000 births of Transportation of the great arteries during 2007-2017 by five-year moving averages, with 95% confidence interval band and Poisson estimated fitted line.
Reports Defects Births Prevalence (95% CI) Predicted Prevalence†
2007-2011 5.3 3.3 11404.7 2.9 (0.9, 7.2) 3.3
2008-2012 6.0 3.7 11354.0 3.3 (1.1, 8.2) 2.9
2009-2013 5.0 3.1 11349.0 2.7 (0.9, 7.3) 2.5
2010-2014 4.0 2.5 11334.7 2.2 (0.7, 6.8) 2.2
2011-2015 3.3 2.1 11377.3 1.8 (0.5, 5.8) 2.0
2012-2016 3.3 2.1 11295.0 1.9 (0.5, 5.9) 1.7
2013-2017 2.3 1.5 10979.7 1.4 (0.2, 5.1) 1.5
Notes: Each row is based on five-year moving averages; Prevalence reported per 10,000 live births; 95% CI=95% Confidence Interval

† Estimated rate based on Poisson model
The p-value test for trend detected a significant decrease in the number of live births with Transportation of the great arteries during 2007-2017. See p-value estimate
Estimate Std. Error t value Pr(>|t|)
-0.12935 0.02141 -6.04081 0.00179

Regional Distribution

Distribution of Transportation of the great arteries in Alaska by Public Health Region of maternal residence at the time of birth. A description of regional breakdowns can be found here. Data suppressed for # of reports < 6.
Reports Defects Births Prevalence (95% CI)
Anchorage 16 10.1 50455 2 (1.1, 3.6)
Gulf Coast - - 7725 -
Interior 11 6.9 22487 3.1 (1.3, 5.8)
Mat-Su 6 3.8 14937 2.5 (0.7, 5.9)
Northern 6 3.7 8520 4.4 (1.3, 10.3)
Southeast - - 7625 -
Southwest - - 11881 -
Notes:Prevalence reported per 10,000 live births; Data suppressed for # of reports < 6; 95% CI = 95% Confidence Interval

Demographics

Some subgroups may be more at risk for having a baby with Transportation of the great arteries. This section provides the descriptive epidemiology of specified maternal, birth, and child characteristics identified from the birth certificate.

Reports Defects Births Prevalence (95% CI)
Sex
  Female 20 12.6 59998 2.1 (1.1, 3.5)
  Male 27 16.9 63632 2.7 (1.6, 4.1)
Birth weight (grams)
  <2500 9 5.5 7231 7.6 (3.0, 16.1)
  2500+ 38 24 116215 2.1 (1.4, 3.1)
Maternal age
  12-19 - - 9156 -
  20-24 15 9.4 32872 2.9 (1.5, 5.2)
  25-29 14 8.8 37743 2.3 (1.1, 4.2)
  30-34 11 6.9 28152 2.5 (1.0, 4.6)
  35-39 - - 12614 -
  40+ - - 3064 -
Maternal race
  Alaska Native/American Indian 16 10 31560 3.2 (1.5, 5.4)
  Asian/Pacific Islander - - 11810 -
  Black - - 5081 -
  White 25 15.8 73595 2.1 (1.2, 3.4)
Maternal education (years)
  <12 - - 11929 -
  12 - - 43162 3.3 (2.0, 5.4)
  12+ - - 65105 1.5 (0.7, 2.6)
Marital status
  Married 23 14.6 78396 1.9 (1.1, 3.0)
  Unmarried 24 14.9 44625 3.4 (1.9, 5.3)
Maternal smoking use
  Reported smoking 10 6.2 16817 3.7 (1.7, 7.8)
  Reported not smoking 35 22.1 104707 2.1 (1.4, 3.2)
Medicaid (mother or child)
  Medicaid 37 23 62666 3.7 (2.3, 5.3)
  non-Medicaid 9 6 60839 1.0 (0.4, 1.9)
Father on birth certificate
  None 9 5.5 6328 8.7 (3.5, 18.4)
  Present 38 24 117302 2.0 (1.4, 3.0)
Notes: Prevalence reported per 10,000 live births; Data suppressed for # of reports < 6; 95% CI = 95% Confidence Interval

Technical notes

Column descriptions

# Reports: Unless otherwise noted, the number of unique reports of the defect received by ABDR during the specified birth year(s). Each report represents a unique child with the specified defect.

# Defects: The estimated true number of reports that are diagnosed defects based on medical record review and case confirmation.

# Births: The number of live births among Alaskan residents that occurred in Alaska during the specified birth year(s).

Prevalence (95% CI): The estimated diagnosed prevalence of the condition and corresponding 95% Confidence Interval. (For information on how the defect prevalence was estimated see below).

Defect prevalence calculation

The estimated defect prevalence was 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 prevalance of birth defects compared to the reported prevalance 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.

See Data analysis methods for more information.

P-value estimate

To evaluate the trend over time and account for under/over-dispersion we constructed a quasi-Poisson regression model. This model assumes the variance is a linear function of the mean and models the estimated number of annual defects by year with a natural log (ln) offset of the annual births. P-values < 0.05 are considered significant, which indicates that the predicted slope is significantly different from a slope of zero.

Data suppression

For region and demographic data tables, values are suppressed based on the number of reports received during the observation period. Counts less than 6 are suppressed (as indicated by ‘-’ in the table). For regions or demographics with only one cell count suppressed a second is suppressed to eliminate the ability to back-calculate the estimate.

References

[1] Congenital Heart Defects- Facts about dextro-Transposition of the Great Arteries (d-TGA)- (CDC). (2020). Retrieved 29 January 2021, from https://www.cdc.gov/ncbddd/heartdefects/d-tga.html

[2] transposition of the great arteries. (2018). Retrieved 29 January 2021, from https://www.mayoclinic.org/diseases-conditions/transposition-of-the-great-arteries/symptoms-causes/syc-20350589

[3] Transposition of the Great Arteries. (2021). Retrieved 29 January 2021, from https://www.chop.edu/conditions-diseases/transposition-great-arteries

[4] Transposition of the Great Arteries (TGA) | Symptoms & Causes. (2021). Retrieved 29 January 2021, from https://www.childrenshospital.org/conditions-and-treatments/conditions/t/transposition-of-the-great-arteries/symptoms-and-causes

Suggested Citation

State of Alaska Department of Health and Social Services, Division of Public Health, Section of Women’s, Children’s, and Family Health. Alaska Birth Defects Registry Condition Report: Transposition of the Great Arteries, Alaska, 2007-2017. Updated July 22, 2020. Available at: http://rpubs.com/AK_ABDR/TGA/07_17.

Contact

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

Updated: May 22, 2021
Contributed by: Dr. James Christiansen, MD
Code source: R:\ABDR\Analysis_New\ABDR_CASECONF\cond_reports\Published_reports\TGA07_17.Rmd