Alaska Birth Defects Registry Condition Report
Fetal Alcohol Syndrome (FAS)
Alaska, 2007-2016
Background
Fetal alcohol syndrome (FAS) falls on the most severe end of the fetal alcohol spectrum disorders (FASD), which are a group of conditions that can occur in a child whose mother drank alcohol during pregnancy.[1] Specifically, alcohol is a teratogen that causes developmental malformations in a fetus.[2] The effects of FASD can include physical abnormalities as well as problems with behavior and learning. Usually the symptoms of FAS are more severe as children often have growth and central nervous system (CNS) problems in addition to problems with learning, memory, communication, vision, and/or hearing. This can affect a child’s ability to relate to their peers and succeed in school.[1]
Diagnosing FAS is made difficult by the lack of medical diagnostic tests and shared symptoms with other disorders, such as ADHD (attention-deficit/hyperactivity disorder). However, doctors can look for things like abnormal facial features, lower-than-average height and weight, CNS problems, and prenatal alcohol exposure.[1]
There is no cure for FAS, but early intervention treatment, like behavior therapy and parent training, can improve a children’s development and reduce the effects of FAS.
No known amount of alcohol is safe during pregnancy, including the early stages of pregnancy when a woman may not be aware that she is pregnant.[2,3] In order to prevent FAS, sexually active women of reproductive age should: 1) avoid alcohol while trying to become pregnant and during pregnancy and 2) avoid becoming pregnant if they use alcohol.
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 ABDR program methodology and lack of standardized diagnostic criteria for the entire spectrum disorder (FASD) limits the ABDR program to estimating FAS prevalence only. The Registry derived an informative prior by calculating a weighted confirmation probability of FAS by estimating the proportion diagnosed with FAS by FASD diagnostic clinics, and the proportion reported to ABDR and reviewed and specified through historical medical records review and case abstraction. Based on the probability of being reported for FAS to ABDR before age 3 years, the informative prior is used to establish the probability of FAS given being reported. A pseudo or proxy is derived to estimate the probability of FAS given not being reported among those reported/detected by ABDR three years of age or greater. Utilizing these three probabilities, the prevalence of FAS is estimated, and accounts for classification and detection variation and is believed to be the most accurate estimation of FAS in Alaska. See Defect prevalence calculation.
For explanations of table columns see Column descriptions.
Prevalence
The prevalence of FAS is estimated to be between 0.3-1.5 out of every 1,000 live births in the United States based on data from children born during 1995-1997.[4]
In Alaska, during 2007-2016, the prevalence of FAS was 1.7 per 1,000 live births.| Reports | Defects | Births | Prevalence (95% CI) | |
|---|---|---|---|---|
| Total | 572 | 189.4 | 113183 | 1.7 (1.4, 1.9) |
| Notes: 95% CI = 95% Confidence Interval | ||||
Trend
Prevalence per 1,000 births of FAS during 2007-2016 by three-year moving averages, with 95% confidence interval band and Poisson estimated fitted line.
| Reports | Defects | Births | Prevalence (95% CI) | Predicted Prevalence† | |
|---|---|---|---|---|---|
| 2007-2009 | 58.7 | 19.3 | 11262.0 | 1.7 (1.1, 2.6) | 1.6 |
| 2008-2010 | 53.0 | 18.0 | 11404.3 | 1.6 (1.0, 2.4) | 1.6 |
| 2009-2011 | 50.0 | 17.3 | 11404.7 | 1.5 (0.9, 2.4) | 1.6 |
| 2010-2012 | 54.7 | 18.4 | 11354.0 | 1.6 (1.0, 2.5) | 1.6 |
| 2011-2013 | 60.0 | 19.6 | 11348.7 | 1.7 (1.1, 2.6) | 1.6 |
| 2012-2014 | 59.0 | 19.4 | 11334.3 | 1.7 (1.0, 2.6) | 1.6 |
| 2013-2015 | 54.7 | 18.4 | 11377.0 | 1.6 (1.0, 2.5) | 1.7 |
| 2014-2016 | 56.0 | 18.7 | 11295.0 | 1.7 (1.0, 2.5) | 1.7 |
|
Notes: Each row is based on three-year moving averages; Prevalence reported per 1,000 live births; 95% CI=95% Confidence Interval † Estimated rate based on Poisson model |
|||||
| Estimate | Std. Error | t value | Pr(>|t|) |
|---|---|---|---|
| 0.00331 | 0.00722 | 0.45861 | 0.66266 |
Regional Distribution
Distribution of FAS 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 | 156 | 59.6 | 46323 | 1.3 (1.0, 1.6) |
| Gulf Coast | 66 | 18.8 | 7048 | 2.7 (1.6, 4.0) |
| Interior | 121 | 38.3 | 20523 | 1.9 (1.4, 2.5) |
| Mat-Su | 24 | 12.5 | 13587 | 0.9 (0.5, 1.5) |
| Northern | 87 | 24.0 | 7812 | 3.1 (2.0, 4.4) |
| Southeast | 45 | 13.9 | 7012 | 2.0 (1.1, 3.2) |
| Southwest | 73 | 22.3 | 10878 | 2.1 (1.3, 3.1) |
| Notes:Prevalence reported per 1,000 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 FAS. 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 | 260 | 87.9 | 54900 | 1.6 (1.3, 2.0) |
| Male | 312 | 101.6 | 58283 | 1.7 (1.4, 2.1) |
| Birth weight (grams) | ||||
| <2500 | 156 | 39.1 | 6582 | 6.0 (4.3, 8.1) |
| 2500+ | 414 | 149.7 | 106420 | 1.4 (1.2, 1.6) |
| Maternal age | ||||
| 12-19 | 50 | 15.9 | 8664 | 1.8 (1.1, 2.9) |
| 20-24 | 154 | 51.1 | 30607 | 1.7 (1.3, 2.2) |
| 25-29 | 176 | 58.1 | 34376 | 1.7 (1.3, 2.2) |
| 30-34 | 107 | 37.6 | 25418 | 1.5 (1.1, 2.0) |
| 35-39 | 67 | 21.2 | 11311 | 1.9 (1.2, 2.8) |
| 40+ | 18 | 5.6 | 2778 | 2.0 (0.8, 4.2) |
| Maternal race | ||||
| Alaska Native/American Indian | 378 | 101.5 | 28829 | 3.5 (2.9, 4.3) |
| Asian/Pacific Islander | 14 | 8.7 | 10598 | 0.8 (0.4, 1.5) |
| Black | 17 | 6.3 | 4581 | 1.4 (0.6, 2.9) |
| White | 155 | 70.4 | 67675 | 1.0 (0.8, 1.3) |
| Maternal education (years) | ||||
| <12 | 180 | 46.9 | 10904 | 4.3 (3.2, 5.6) |
| 12 | 252 | 78.4 | 40057 | 2.0 (1.6, 2.4) |
| 12+ | 107 | 54.9 | 58944 | 0.9 (0.7, 1.2) |
| Marital status | ||||
| Married | 104 | 60.8 | 71658 | 0.8 (0.7, 1.1) |
| Unmarried | 451 | 124.5 | 41006 | 3.0 (2.5, 3.6) |
| Maternal smoking use | ||||
| Reported smoking | 343 | 86.7 | 15727 | 5.5 (4.4, 6.8) |
| Reported not smoking | 203 | 95.8 | 95579 | 1.0 (0.8, 1.2) |
| Medicaid (mother or child) | ||||
| Medicaid | 529 | 150.8 | 57258 | 2.6 (2.2, 3.1) |
| non-Medicaid | 43 | 38.6 | 55806 | 0.7 (0.5, 0.9) |
| Father on birth certificate | ||||
| None | 114 | 29 | 5634 | 5.2 (3.6, 7.4) |
| Present | 458 | 160.4 | 107549 | 1.5 (1.3, 1.7) |
| Notes: Prevalence reported per 1,000 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:
\[PPV (Positive Predictive Value) = p(defect|report)\] \[NPV (Negative Predictive Value) = p(\overline{defect}|\overline{report})\]
\[p(defect) \approx [p(report)\cdot PPV]+[p(\overline{report})\cdot (1-NPV)]\]
PPV and NPV estimates for FAS are derived by utilizing informative information regarding confirmed classification of FAS through FASD diagnostic teams and historical ABDR abstraction and confirmations utalizing the CDC criteria. The probability of FAS given being reported for an ICD code reflective of alcohol affected births to ABDR was independently calculated for those reported before age 3 and among those reported age 3 or greater. For both, cases seen by a FASD diagnostic clinic were evaluated as truth, with all other reported cases weighted accordingly to derived FAS confirmation probabilities.
FAS confirmation
FAS total = Average[p(4-digit FAS diagnosis by FASD diagnostic clinics),p(4-digit FAS diagnosis by FASD diagnostic clinics among those reported with a FASD code), mean(FAS case confirmation through ABDR abstractions, where suspected cases estimated between 1.0 and 0.25 truth)]
FAS <3 years = [(FASD reported to ABDR <3*(mean(FAS total, <3 4-digit confirmation)))+(4-digit confirmation total)]/FASD reported to ABDR < 3
FAS 3+ years = [(FASD reported to ABDR 3+*(mean(FAS total, 3+ 4-digit confirmation)))+(4-digit confirmation total)]/FASD reported to ABDR 3+
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] Centers for Disease Control and Prevention. Facts about FASDs, https://www.cdc.gov/ncbddd/fasd/facts.html; 2017 [accessed 11.09.2017]
[2] Association of Reproductive Health Professionals. Facts about Fetal Alcohol Spectrum Disorders (FASDs), http://www.arhp.org/uploadDocs/FASDs.pdf; 2014 [accessed 11.16.2017]
[3] American College of Obstetricians and Gynecologists. Fetal Alcohol Spectrum Disorder (FASD); 2017 [accessed 11.16.2017]
[4] Centers for Disease Control and Prevention. Fetal Alcohol Syndrome — Alaska, Arizona, Colorado, and New York, 1995–1997. MMWR 2002;51(20); 433-5. Available at: https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5120a2.htm
Resources
Centers for Disease control and Prevention
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: Fetal Alcohol Syndrome (FAS), Alaska, 2007-2016. Updated July 23, 2020. Available at: http://rpubs.com/AK_ABDR/FAS07_16.
Contact
Alaska Birth Defects Registry (ABDR)
3601 C Street, Suite 358
Anchorage, AK 99503
(907) 269-3400 phone
(907) 754-3529 fax
Email: hssbirthdefreg@alaska.gov
ABDR Website: http://dhss.alaska.gov/dph/wcfh/Pages/mchepi/abdr
Updated: July 23, 2020
Code source: R:\ABDR\Analysis_New\ABDR_CASECONF\cond_reports\Published_reports\FAS07_16.Rmd
