Estimating the Prevalence of Fetal Alcohol Syndrome: A Summary

Article excerpt

Since the late 1970s, many studies have reported on the prevalence of fetal alcohol syndrome (FAS), alcohol-related birth defects (ARBD), and alcohol-related neurodevelopmental disorders (ARND). The three main types of research methods used in these studies are passive surveillance, clinic-based studies, and active case ascertainment. This article describes each of these methods, including their strengths and weaknesses, and summarizes the estimated prevalence of FAS produced by each of these approaches. The maternal risk factors associated with FAS and other alcohol-related anomalies include advanced maternal age, low socioeconomic status, frequent binge drinking, family and friends with drinking problems, and poor social and psychological indicators. Overall, the available literature points to a prevalence rate of FAS of 0.5 to 2 cases per 1,000 births in the United States during the 1980s and 1990s. KEY WORDS: fetal alcohol syndrome; prevalence; epidemiological indicators; alcoholrelated neurodevelopmental disorder; birth defects; statistical estimation; data collection; clinical aspects; population dynamics; risk factors; research in practice; research quality

Establishing the prevalence1 and other epidemiological characteristics of fetal alcohol syndrome (FAS), alcohol-related birth defects (ARBD), and alcohol-related neurodevelopmental disorder (ARND)2 has been a difficult challenge ever since Jones and colleagues (Jones and Smith 1973; Jones et al. 1973) described the first cases of FAS. Researchers have been constantly challenged by issues related to case finding, sampling, diagnostic criteria, and the coordination of interdisciplinary activities. Although the diagnostic features of FAS are generally well established, the specific assessment techniques used to make the definitive diagnosis are still matters of debate. Furthermore, the criteria for ARBD and ARND (formerly referred to as fetal alcohol effects [FAE]) remain even more in question today (Stratton et al. 1996; Aase 1994; Aase et al. 1995; Astley and Clarren 2000). Because of questions of assessment methods and difficulties associated with access to cases, studies that have attempted to determine the prevalence of FAS, ARBD, and ARND are limited in number, vary widely in their methodology, and may leave the typical reader puzzled about the true pattern and the frequency of occurrence of these disorders.

This article will summarize the common methods used to study the prevalence and other epidemiological characteristics of FAS in the United States and review both similar and unique findings that have emerged in the literature from other countries. For each method, we present a survey of the studies conducted and summarize the research findings. We will highlight the biases, strengths, weaknesses, and key findings produced by each approach, and discuss the different populations studied.

THREE COMMON APPROACHES TO THE EPIDEMIOLOGICAL STUDY OF FAS

Researchers used three main approaches to study the prevalence and patterns of occurrence of FAS, ARBD, and ARND: passive systems, clinic-based studies, and active case ascertainment approaches. Of these three approaches, clinic-based studies are the most common, followed by passive systems, and then active case ascertainment. Passive systems are generally the least expensive, followed by clinic-based studies; active case ascertainment studies are frequently the most costly and time intensive (Stratton et al. 1996).

Passive Surveillance Systems

Researchers using passive systems to study FAS epidemiology use existing record collections in a particular geographical catchment area (e.g., a town or state). Researchers must first establish the criteria for defining a diagnosis of FAS, ARBD, or ARND, and then a team of reviewers looks for documented or probable cases of children born with FAS and diagnosed in a particular time period. Three types of records are generally reviewed: birth certificates, special registries for children with developmental disabilities or birth defects, and/or the medical charts of hospitals and physicians. …