Tetralogy of Fallot
Alaska, 2007-2017
Background
Tetralogy of Fallot (TOF) is a birth defect of the heart consisting of four components. These include: 1) a hole between the two ventricles (ventricular septal defect), 2) a narrowed pulmonary valve and pulmonary artery, 3) an enlarged aorta which overrides the ventricular septum, and 4) an abnormally thickened wall of the right ventricle (hypertrophy). [1] Due to the obstruction of pulmonary blood flow, TOF may present with cyanosis (blue skin tone), respiratory distress, poor weight gain, and a heart murmur. [2] If the degree of obstruction is mild, cyanosis may be mild or absent and might escape detection. Tetralogy of Fallot can be diagnosed during pregnancy by fetal ultrasound (echocardiogram) or after birth using a variety of tests such as pulse oximetry, chest x-ray, cardiac catheterization, electrocardiogram and echocardiogram. [3] Tetralogy of Fallot may be associated with a genetic defect 22q11 deletion. (ref) Maternal pregestational diabetes is a modifiable risk factor for TOF. (ref) Treatment for this defect can include interventional catheterization or surgical procedures to widen the pulmonary artery to improve pulmonary blood flow and closing the hole between the ventricles with a patch. [4] Because an infant with Tetralogy of Fallot 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
Tetralogy of Fallot occurs in about 4 out of every 10,000 live births in the United States. This results in about 1,660 babies diagnosed with Tetralogy of Fallot nationally each year.[1]
In Alaska, during 2007-2017, the prevalence of Tetralogy of Fallot was 3.1 per 10,000 live births.| Reports | Defects | Births | Prevalence (95% CI) | |
|---|---|---|---|---|
| Total | 61 | 38.6 | 123630 | 3.1 (2.2, 4.2) |
| Notes: 95% CI = 95% Confidence Interval | ||||
Trend
Prevalence per 10,000 births of Tetralogy of Fallot 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 | 8.0 | 5.1 | 11404.7 | 4.4 (1.8, 9.8) | 5.0 |
| 2008-2012 | 7.0 | 4.4 | 11354.0 | 3.9 (1.5, 8.9) | 4.3 |
| 2009-2013 | 8.0 | 5.1 | 11349.0 | 4.4 (1.8, 9.8) | 3.7 |
| 2010-2014 | 6.3 | 4.0 | 11334.7 | 3.5 (1.3, 8.6) | 3.2 |
| 2011-2015 | 6.0 | 3.8 | 11377.3 | 3.3 (1.2, 8.0) | 2.7 |
| 2012-2016 | 4.0 | 2.5 | 11295.0 | 2.2 (0.6, 6.3) | 2.4 |
| 2013-2017 | 2.3 | 1.5 | 10979.7 | 1.3 (0.2, 5.1) | 2.0 |
|
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 |
|||||
| Estimate | Std. Error | t value | Pr(>|t|) |
|---|---|---|---|
| -0.14852 | 0.03819 | -3.88889 | 0.01154 |
Regional Distribution
Distribution of Tetralogy of Fallot 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 | 20 | 12.6 | 50455 | 2.5 (1.4, 4.2) |
| Gulf Coast | - | - | 7725 | - |
| Interior | 15 | 9.5 | 22487 | 4.2 (2.1, 7.6) |
| Mat-Su | - | - | 14937 | - |
| Northern | 7 | 4.4 | 8520 | 5.2 (1.9, 12) |
| Southeast | - | - | 7625 | - |
| Southwest | 10 | 6.3 | 11881 | 5.3 (2.4, 11) |
| 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 Tetralogy of Fallot. 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 | 29 | 18.3 | 59998 | 3.1 (1.9, 4.7) |
| Male | 32 | 20.2 | 63632 | 3.2 (2.0, 4.8) |
| Birth weight (grams) | ||||
| <2500 | 22 | 13.9 | 7231 | 19.2 (10.6, 30.7) |
| 2500+ | 39 | 24.7 | 116215 | 2.1 (1.4, 3.1) |
| Maternal age | ||||
| 12-19 | - | - | 9156 | - |
| 20-24 | 19 | 12 | 32872 | 3.6 (2.1, 6.4) |
| 25-29 | 20 | 12.6 | 37743 | 3.4 (1.8, 5.6) |
| 30-34 | 10 | 6.3 | 28152 | 2.2 (1.0, 4.6) |
| 35-39 | 6 | 3.8 | 12614 | 3.0 (0.9, 7.0) |
| 40+ | - | - | 3064 | - |
| Maternal race | ||||
| Alaska Native/American Indian | 23 | 14.5 | 31560 | 4.6 (2.7, 7.4) |
| Asian/Pacific Islander | - | - | 11810 | - |
| Black | - | - | 5081 | - |
| White | 31 | 19.6 | 73595 | 2.7 (1.7, 4.0) |
| Maternal education (years) | ||||
| <12 | 9 | 5.7 | 11929 | 4.8 (1.9, 9.8) |
| 12 | 25 | 15.8 | 43162 | 3.7 (2.1, 5.7) |
| 12+ | 24 | 15.2 | 65105 | 2.3 (1.4, 3.8) |
| Marital status | ||||
| Married | 35 | 22.1 | 78396 | 2.8 (1.9, 4.2) |
| Unmarried | 26 | 16.4 | 44625 | 3.7 (2.2, 5.8) |
| Maternal smoking use | ||||
| Reported smoking | 16 | 10.1 | 16817 | 6.0 (3.3, 10.9) |
| Reported not smoking | 45 | 28.5 | 104707 | 2.7 (1.9, 3.9) |
| Medicaid (mother or child) | ||||
| Medicaid | 45 | 28.5 | 62666 | 4.5 (3.1, 6.5) |
| non-Medicaid | 16 | 10.1 | 60839 | 1.7 (0.9, 3.0) |
| Father on birth certificate | ||||
| None | 6 | 3.8 | 6328 | 6.0 (1.7, 13.8) |
| Present | 55 | 34.8 | 117302 | 3.0 (2.1, 4.0) |
| 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 Tetralogy of Fallot (CDC). (2020). Retrieved 01 February 2021, from https://www.cdc.gov/ncbddd/heartdefects/tetralogyoffallot.html
[2] Tetralogy of Fallot. (2018). Retrieved 01 February 2021, from https://www.mayoclinic.org/diseases-conditions/tetralogy-of-fallot/symptoms-causes/syc-20353477
[3] Tetralogy of Fallot (TOF). (2021). Retrieved 01 February 2021, from https://www.chop.edu/conditions-diseases/tetralogy-fallot
[4] Tetralogy of Fallot. (2021). Retrieved 01 February 2021, from https://www.mottchildren.org/conditions-treatments/ped-heart/conditions/tetralogy-fallot
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: Tetralogy of Fallot, Alaska, 2007-2017. Updated June 22, 2021. Available at: http://rpubs.com/AK_ABDR/Tetralogy of Fallot/07_17.
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: June 22, 2021
Code source: R:\ABDR\Analysis_New\ABDR_CASECONF\cond_reports\Published_reports\TOF07_17.Rmd
