Background

A cleft lip is congenital condition when a baby’s lip does not form properly during early pregnancy [1]. Cleft lip occurs when the lip does not come together during development, separating the lip either on one side (unilateral) or on both sides (bilateral) [2]. Cleft palate occurs when the roof of the mouth fails to join together resulting in an opening in either the front of the palate, the back of the palate, or both [1]. The lip and palate develop separately during pregnancy, therefore, a baby can have either cleft lip, cleft palate, or both cleft lip and cleft palate [2]. Orofacial clefts are one of the most common birth defects in the United States [2, 3]. While the exact cause for most cases of orofacial clefts is unknown. It is believed that a combination of environmental factors, mothers behaviors during early pregnancy (what she eats/drinks and medicine consumed), and genetic factors may contribute to orofacial clefts [1, 2].

Methodology

The 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 a complete explanation of the methodology used for generating estimates.

While this report provides the most precise estimates, caution should be used in interpreting prevalence estimates based on conditions with <30 annual reports, as they are potentially vulnerable to large year-to-year variation.

For explanations of table columns see column descriptions.

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

According to the 2019 annual report released by the National Birth Defects Prevention Network (NBDPN), the prevalence of cleft lip from 2010-2014 was was 3.56 (95% CI 3.39–3.74) per 10,000 live births.[3]

In Alaska, during 2007-2021, the prevalence of cleft lip was 4.1 per 10,000 live births.
Reports Defects Births Prevalence (95% CI)
158 66.3 162989 4.1 (3.2, 5.2)
Notes: 95% CI = 95% Confidence Interval

Trend

Prevalence per 10,000 births of Cleft Lip during 2007-2021 by five-year moving averages, with 95% confidence interval band and Poisson estimated fitted line.
Trend tests with a p-value of 0.05 or lower detect a statistically significant increase or decrease in the number of live births with Cleft Lip during 2007-2021. See p-value estimate
Estimate Std. Error t value Pr(>|t|)
-0.02235 0.01541 -1.44984 0.18104
Notes: 95% CI = 95% Confidence Interval

Regional Distribution

Distribution of Cleft Lip 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.

Demographics

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

Accompanying Diagnoses

The ten diagnoses most commonalty associated with Cleft Lip.

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:

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

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

For cleft conditions, many cases were determined to be a different cleft defect than what was reported. Therefore, an additional intra-conditional probability was calculated and applied to the prevalence estimates. This probability accounts for the misclassified cleft conditions that were reported. In addition, a number of individuals were reported for more than one, or all three possible cleft conditions. For these individuals a separate PPV and NPV was calculated and applied.

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 Facts about Cleft Lip and Cleft Palate | CDC. (2017). Centers for Disease Control and Prevention. Retrieved 22 March 2019, from https://www.cdc.gov/ncbddd/birthdefects/cleftlip.html

2 Introduction to Cleft & Craniofacial Conditions - ACPA Family Services. (2019). Cleftline.org. Retrieved 22 March 2019, from https://cleftline.org/family-resources/introduction-to-cleft-craniofacial-conditions/

3 Mai CT, Isenburg JL, Canfield MA, Meyer RE, Correa A, Alverson CJ, Lupo PJ, Riehle‐Colarusso T, Cho SJ, Aggarwal D, Kirby RS. National population‐based estimates for major birth defects, 2010–2014. Birth Defects Research. 2019; 111(18): 1420-1435

Authorship

Maternal and Child Health (MCH) senior epidemiologist Dr. Jared Parrish, PhD conceived of the presented analysis. Alaska Birth Defects Registry program manager and epidemiologist Chris Barnett, MS MPH and Dr. Jared Parrish, PhD developed the theory and performed the computations. Research analysts Monica Mills and Jordyn Lord managed data collection and storage. All authors discussed the results and contributed to the final report.

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: Cleft Conditions, Alaska, 2007-2021. Updated April 11, 2024. Available at: http://rpubs.com/AK_ABDR/cleft_Conds

Contact

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

Updated: April 11, 2024
Code source: R:\ABDR\Analysis_New\ABDR_CASECONF\cond_reports\Published_reports\Targets_publications\cleft_lip_tar.Rmd