Craniosynostosis
Alaska, 2016-2021
Background
Craniosynostosis is a condition in which the bones of a newborn’s skull fuse prematurely before the brain is fully formed. With Cranisosynotsis, one or more fibrous joints between the bones of a newborn’s skull (cranial sutures) close prematurely. As the baby’s brain grows, the skull can become misshapen. Typically, the sutures remain flexible, allowing a baby’s skull to expand as the brain grows. Craniosynostosis usually involves premature fusion of a single cranial suture, but in some cases, multiple sutures can be affected.The cause of craniosynostosis is often unknown, but sometimes, it’s related to specific genetic disorders or syndromes (Apert syndrome, Pfeiffer syndrome, or Crouzon syndrome).1,2 The diagnosis of craniosynostosis typically requires an evaluation by a pediatric neurosurgeon or a specialist in plastic and reconstructive surgery, which may include imaging, physical examination, and genetic testing. 3 Surgery is the primary treatment for correcting the head shape and creating room for the brain to grow properly. The type of surgery will depend on the condition and whether there’s an underlying genetic syndrome. Sometimes, more than one surgery is required. Mild cases of craniosynostosis may not need treatment or only a specially molded helmet to help reshape the head.Without treatment, craniosynostosis may cause developmental delays, cognitive impairments, vision problems, seizures, headaches, and a misshapen skull. However, the risk for these complications is small with treatment, and most newborns with craniosynostosis live typical healthy lives.2
Epidemiology
Alaska Birth Defects Registry (ABDR) records birth defects reported by healthcare providers using International Classification of Disease (ICD) billing codes. However, relying on these ICD codes alone can result in misclassifying diagnosed conditions.
The estimates in this report are derived by conducting a 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 then used to estimate the prevalence of the diagnosed defect among Alaskan residents. See Defect prevalence calculation.
For explanations of table columns see Column descriptions.
Prevalence
It is estimated that about 1 in every 2,500 babies is born with craniosynostosis in the United States.1
In Alaska, during 2007-2021, the prevalence of Craniosynostosis was 4.7 per 10,000 live births.| Reports | Defects | Births | Prevalence (95% CI) |
|---|---|---|---|
| 216 | 76.2 | 162989 | 4.7 (3.7, 5.8) |
| Notes: 95% CI = 95% Confidence Interval | |||
Trend
Prevalence per 10,000 births of Craniosynostosis during 2007-2021 by three-year moving averages, with 95% confidence interval band and Poisson estimated fitted line.| Estimate | Std. Error | t value | Pr(>|t|) |
|---|---|---|---|
| 0.28689 | 0.03934 | 7.29245 | 0.00001 |
Regional Distribution
Distribution of Craniosynostosis in Alaska 2016-2021 by Public Health Region of maternal residence at the time of birth. A description of regional breakdowns can be found here. Data suppressed for number of reports < 6.
Demographics
Craniosynostosis may occur in some subgroups more often than others. This section provides the descriptive epidemiology of specified maternal, birth, and child characteristics identified from the birth certificate.
Accompanying Diagnoses
The ten diagnoses most commonly associated with Craniosynostosis in Alaska, 2016-2021.
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 number of reports diagnosed defects based on medical record review and case confirmation.
Births: The number of live births among Alaskan residents 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).
Odds Ratio: The odds ratio is a measure of association. Here, we used the odds ratio to measure the association of a condition and its prevalence within the seven public health regions of the state. All odds ratios are calculated by comparing each public health region to the rest of the state. The higher the odds ratio, the higher the association.
P-value: The P-value is a statistical test that aims to calculate the probability a result occurs at random (due to chance). Here, we calculate p-values to help understand the association between the condition and the seven public health regions of the state. The lower the p-value, the less likely the differences in public health regions are due to chance.
Predicted prevalence: The predicted prevalence is a metric calculated by a quasi-poisson regression model fit to the individual yearly prevalence estimates. Here, we use the quasi-poisson regression model to test the statistical significance of a trend in overdispersed count data for our condition of interest.
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). Defect prevalence estimates are more accurate estimates of the actual diagnosed prevalence of birth defects compared to the reported prevalence estimates in Alaska. The registry obtains reports from medical providers using International Classification of Disease (ICD) codes extracted from individual systems, which, when aggregated, may not reflect true diagnostics. Readers should use caution when interpreting and comparing the reported prevalence estimates with national estimates.
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 prevalence of birth defects compared to the reported prevalence 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. Birth Defects, Available from: www.cdc.gov Retrieved 14 November 2024
[2] Mayo Clinic: Diseases & Conditions - Craniosynostosis. Available from: https://www.mayoclinic.org/diseases-conditions/craniosynostosis/symptoms-causes/syc-20354513 Retrieved 14 November 2024
[3] Cincinnati Children’s Health Library: Craniosynostosis Available from: https://www.cincinnatichildrens.org/health/c/craniosynostosis Retrieved 14 November 2024
Suggested Citation
State of Alaska Department of Health, Division of Public Health, Section of Women’s, Children’s, and Family Health. Alaska Birth Defects Registry Condition Report: Craniosynostosis, Alaska, 2007-2021. Updated December 10, 2024. Available at: http://rpubs.com/AK_ABDR/Craniosynostosis.
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: December 10, 2024
Code source:
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