Fetal Alcohol Disorders Much More Common Than Prior Estimates

Norra MacReady

February 06, 2018

The prevalence of fetal alcohol spectrum disorders (FASD) may be much higher than previously thought, according to a new analysis published online today in JAMA.

In the United States, the commonly accepted prevalence estimate for FASD, including fetal alcohol syndrome, partial fetal alcohol syndrome, and alcohol-related neurodevelopmental disorder, is 10 per 1000 children, or 1%, the authors write.

However, in the current study, conducted in four US communities, prevalence ranged from 1.1% to 5.0%, using a conservative estimation approach, and as high as 3% to 10% when a less conservative approach was used.

In absolute terms, the authors diagnosed FASD in 222 children in the current study among 6054 who were screened for growth, development, or both. Yet only 2 of those participants had received a previous FASD diagnosis.

In comparison, in 2012, the Centers for Disease Control and Prevention estimated the prevalence of autism spectrum disorders at 14.6 per 1000 children, or about 1.5%, the authors note.

The results "are consistent with mounting evidence that harmful fetal alcohol exposure is common in the United States today and highlight the public health burden due to [FASD]," they warn. The authors caution that these findings may not be generalizable to all communities, although the study sample represented a diverse population.

In an accompanying editorial, Shannon Lange, MPH, from the Institute for Mental Health Policy Research at the Centre for Addiction and Mental Health in Toronto, Ontario, Canada, and colleagues state that fetal alcohol effects "must be recognized globally as a public health problem." The findings of this study imply that "many cases are either missed or misdiagnosed; additional supports should be made available for affected children and adults; surveillance systems for affected children and for prenatal alcohol exposure are needed; and improved prevention efforts targeting prenatal alcohol use are clearly required."

Multiple Sites, Methods Used

For the analysis, Dr. May and colleagues conducted a cross-sectional study of first-graders in public and private elementary schools in four communities across the United States, located in the Midwest, the Rocky Mountain area, the Southeast, and the Pacific Southwest. The children were recruited across two academic years between November 15, 2010, and July 12, 2016, yielding a total of 8 independent samples.

The authors employed two methods to estimate FASD prevalence. The first, and most conservative, approach estimated minimum prevalence and 95% confidence intervals (CIs), "using the total number of children classified within the FASD continuum for a given sample as the numerator and the total number of eligible children at that site for that year as the denominator," they explain. The second, less conservative, approach involved use of a weighting technique to estimate prevalence and 95% CIs.

Three sampling methods were used at the different sites to identify students who might have FASD. Children might be selected for further examination based on a height, weight, and head circumference at the 25th percentile or less or because they were randomly chosen to participate. "Assessment tools were selected for the 4 domains germane to the spectrum of FASD: growth, dysmorphology, neurodevelopment, and prenatal alcohol exposure," the authors write.

On the basis of the initial assessment findings or the sampling method, children then went on for further evaluation consisting of more extensive cognitive, academic, and behavioral testing, supplemented with maternal or other collaborative interviews, including questions about maternal alcohol use during pregnancy. These findings were then reviewed and diagnoses assigned in case conferences by two research teams using a common set of standards.

Of 13,146 children in all the participating classrooms, 2962 were evaluated for FASD in the case conferences, and of those children, "27 met criteria for fetal alcohol syndrome, 104 met criteria for partial fetal alcohol syndrome, and 91 met criteria for alcohol-related neurodevelopmental disorder," the authors write. However, only 2 of those children had already been classified with an FASD, "although many parents and guardians were aware of the learning and behavioral challenges facing their children."

Using conservative methods of estimation, the prevalence of FASD ranged from a low of 11.3 (95% CI, 7.8 - 15.8) per 1000 children in one Midwestern sample to a high of 50.0 (95% CI, 39.9 - 61.7) per 1000 children in one Rocky Mountain sample.

With the less conservative, weighted approach, prevalence ranged from 31.1 (95% CI, 16.1 - 54.0) per 1000 children in one Southeastern sample to 98.5 (95% CI, 57.5 - 139.5) per 1000 in one Rocky Mountain sample. Prevalence was higher in the weighted sample, the authors explain, "due to the use of denominators restricted to those children who had received a full evaluation."

The authors conclude, "These findings may represent more accurate US prevalence estimates than previous studies, but may not be generalizable to all communities."

In their editorial, Lange and colleagues point out that "these new estimates are up to 10 times higher than those previously reported using similar methods from 2 single-site studies, and up to 5 times higher than a recent meta-analysis of 6 studies from the United States with a pooled prevalence of 2%."

The finding that only two of 222 children had already been diagnosed with FASD indicates that "a universal diagnostic approach needs to be accepted or developed," the editorialists add. "Ideally, novel and reliable biomarkers for detecting fetal alcohol effects will be identified, which could have significant implications for intervention and therapeutic services."

What is more, the findings demonstrate the need for comprehensive surveillance systems internationally to monitor for the prevalence of FASD and for alcohol use by pregnant women. In the United States, the high prevalence of these disorders "suggests better education of girls and women of childbearing age about the detrimental consequences of alcohol use during pregnancy on the fetus is needed," they conclude.

One study author reported grant support from the National Institute on Alcohol Abuse and Alcoholism and personal fees and honorarium from the Alcohol Center for grant reviews. The authors and editorialists have disclosed no relevant financial relationships.

JAMA. 2018;319:474-482, 448-449. Article

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