Fetal alcohol spectrum disorders likely to be vastly underdiagnosed in US

1. A multisite, cross-sectional study found a large mismatch between previously diagnosed fetal alcohol spectrum disorders and the actual prevalence of cases identified.

Evidence Rating Level: 2 (Good)

Study Rundown: Fetal alcohol spectrum disorders (FASD) are the leading cause of preventable intellectual disability. Despite how common FASD is in the US population, previous estimates of prevalence have been very inaccurate and often are hard to generalize, as they tend to be done at only one site. In this cross-sectional study, the prevalence of FASD were estimated at four distant sites within the US. Though there was some regional variation, the prevalence of FASD was estimated to be between 1.1 to 5%. Strikingly, only about 1% of FASD cases identified by the team of experts was previously diagnosed, though parents and guardians were generally aware of the behavioral abnormalities their children exhibited.

Due to the rigorous design, this study is likely to be the most accurate in terms of prevalence estimates for FASD. However, the consent rate to be screened was just under 60%, indicating an important source of potential bias. In addition, it is not clear how generalizable the prevalence estimates are from these four sites to other locations in the US, even within the same region. Finally, the rate of undiagnosed FASD cases in this study was much higher than other studies, though the use of active case ascertainment in this study suggests that the undiagnosed rate may be higher than previously perceived.

Click to read the study, published in JAMA

Relevant Reading: Misdiagnosis and Missed Diagnoses in Foster and Adopted Children With Prenatal Alcohol Exposure

In-Depth [cross-sectional cohort]: A total of 13 146 children (consent rates were 36.9 to 92.5%, depending on site; mean 59.9%) were recruited from four distinct locations in the US: a Midwest town, a Rocky-Mountain town, a Southeast town, and a Pacific Southwest city. Active case ascertainment, a common methodology, a single classification system, and expert in-person evaluations were used. Conservative FASD prevalence estimates ranged from 11.3 (CI₉₅ 7.8 to 15.8) to 50.0 (CI₉₅ 39.9 to 61.7) cases per 1000 people. Weighted prevalence estimates ranged from 31.1 (CI₉₅ 16.1 to 54.0) to 98.5 (CI₉₅ 57.5 to 139.5) cases per 1000 people. Only 2 of the 222 cases of FASD were diagnosed prior to this study.

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