Systematic Review on the Prevalence of FASD

ABSTRACT

Background

Fetal alcohol spectrum disorders (FASD) constitutes a national public health problem with serious education, social and economic implications for society as those affected suffer a lifelong disability and may need lifelong support. An understanding of the epidemiological aspects of FASD may provide essential knowledge to map the burden of the condition in a variety of settings and populations.

Objectives

To conduct a systematic review and meta-analysis of the existing research-based evidence on the prevalence of FASD in a variety of settings (community, schools, foster care system, correctional systems and specialized care).

Methods

Electronic searches in biomedical electronic databases were conducted from database inception to December 2012. In addition, reference lists of reviews and retrieved articles, scientific meeting proceedings, government documents, theses and dissertations were sought to identify additional studies. Included in the review were primary studies assessing the prevalence of FASD, fetal alcohol syndrome (FAS), partial fetal alcohol syndrome (pFAS), alcohol-related neurodevelopmental disorders (ARND) or alcohol-related birth defects (ARBD) in children, youth or adult populations in communities, schools, foster care or correctional systems. Studies must have reported numeric data to enable the calculation of prevalence rates for the conditions of interest. Whenever possible (i.e., in absence of statistical heterogeneity across the studies), meta-analyses of the prevalence of FASD were conducted separately for each FASD category (i.e., FAS, pFAS, ARND, ARBD, and FASD-overall, including composite definitions of the condition).

Results

The literature searches identified a total of 1872 citations. After screening and applying the eligibility criteria, 54 unique studies were included in the review. The majority of studies have been conducted between 1980 and 2012, with most of them published in peer-reviewed journals.

The majority of studies on FASD prevalence have been conducted in North America and Europe. Countries that individually accounted for the largest number of studies were the USA (15 studies) and South Africa (12 studies). Nine studies assessing the prevalence of FASD in Canada were identified in this review.
Seven studies evaluated the prevalence of the entire FASD spectrum as a whole, whereas 18 studies evaluated the prevalence of FASD as a composite of certain subtypes (e.g., FAS plus pFAS; FAS plus ARND and ARBD). Among the different FASD subtypes, estimates of FAS prevalence were reported in the vast majority of the studies (46 studies) followed by pFAS (19 studies), ARND (10 studies) and ARBD (four studies) prevalences.

Substantial heterogeneity in FASD prevalence estimates were identified across the studies included in the review. Some of the variations in prevalence across the studies can be attributed to many factors, including differences in the methods of case ascertainment and diagnostic criteria, study participants’ age, and methodological characteristics of the studies, among others. Variation in prevalence are also likely to reflect true variations in different geographic and or sub populations.

Prevalence of FASD in the community. Studies assessing the prevalence of FASD in community and population-based samples reported estimates that ranged from 0.02% to 0.5% which translate to FASD rates of 0.2 to 5 per 1000 population. Prevalence estimates were substantially heterogeneous for FAS (0.0006% to 0.3%), as the studies used different methods for case identification that included birth certificates and medical chart review (which reported the lowest prevalence rates) as well as active case ascertainment methods. Similar heterogeneity was identified for pFAS (0.0006% to 0.3%) and both ARND and ARBD estimates (1.08% and 0.37%).

Prevalence of FASD in schools. Results of this review found wide variations in the rate of overall FASD in studies conducted in school settings, ranging from 0.5% to 10.7%. Meta-analyses of the prevalence of specific FASD subtypes provided more reliable information after controlling for potential sources of heterogeneity. A meta-analysis of FAS studies excluding those conducted in South Africa (which are recognized for reporting systematically higher rates of FASD in a region with one of the highest rates of alcohol consumption per capita in the world) yielded a pooled estimate of 0.36% which translates to a rate of 3.6 per 1000 population. The pooled prevalence of pFAS in school settings was higher after adjusting for inadequate sampling strategies: 2.9%, which translates to a rate of 29 per 1000 population. The pooled prevalence of ARND was calculated in 0.23%, for a rate of 2.3 per 1000 population.

Prevalence of FASD among children in foster care. Prevalence estimates of overall FASD in foster care settings ranged from 30.5% to 52%, which translate to FASD rates of 305 to 520 per 1000 population in foster care settings. For FAS alone, a meta-analysis of studies using formal diagnostic criteria for case identification showed that approximately 21% of children in foster care are likely to have the condition. Prevalence estimates for other subtypes such as pFAS, ARND and ARB were also high, ranging from 2% to 14% depending on the methods of diagnosis and case ascertainment.

Prevalence of FASD in prisons and correctional facilities. Estimates of FASD prevalence in correctional systems were derived from studies conducted in Canada and the USA with numbers ranging between 9.8% and 23.3%. More reliable data using active case ascertainment strategies yielded estimates of 1.04% for FAS, 10% for pFAS and 4.1 to 8.7% for ARND.

Prevalence of FASD in Aboriginal populations. Prevalence estimates of overall FASD in Aboriginal populations varied greatly according to the setting in which the studies were conducted. The majority of studies that assessed FASD prevalence in Aboriginal peoples were conducted in Canada. FASD prevalence estimates were higher among Aboriginal youth in correctional facilities (26.9%) and lower in community samples (0.17%). A pooled estimate of FAS prevalence in Aboriginal peoples was calculated in 0.2% (95% CI: 0.1, 0.3, six studies) for a rate of 2 FAS cases per 1000 population, which is not substantially higher than those identified in community samples of the general population. Estimates from two studies on pFAS in Aboriginal populations ranged from 0.13% to 3.9%. Prevalence of ARND in Aboriginal peoples in one study reported a rate of 0.02% (relative to the total population), which translates to a rate of 0.2 per 1000 live births.

Prevalence of FASD in other specialized settings. Composite estimates of FASD in special education settings ranged from 2.1% to 8.8%. A meta-analysis of the prevalence of FAS among children in special education yielded a pooled FAS prevalence rate of 4.9% (95% CI: 2.5, 7.3), whereas the prevalence of pFAS among children attending special education schools was 5.4%.

Conclusions

FASD prevalence rates have been evaluated in a variety of settings including the community, schools, foster care systems, prisons and correctional systems. The magnitude of FASD prevalence vary according to the setting in which it was evaluated, with higher estimates identified in foster and justice systems compared to those obtained from community and school samples. All of them, however, deserve attention for the planning and organization of prevention strategies. The epidemiology of FASD does not seem to be isolated into a specific region and impacts many communities around the world. There is a need for continued good quality research on the prevalence of FASD to provide a basis for health policy and resource allocation for prevention initiatives and clinical and social services.

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