National Drug Strategy
National Drug Strategy

Intergovernmental committee on Drugs working party on Fetal Alcohol Spectrum Disorders

Monograph

Fetal Alcohol Spectrum Disorders in Australia: An Update

June 2012

5.1 Challenges in monitoring the incidence and prevalence of FASD

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A number of challenges exist in monitoring rates of Fetal Alcohol Spectrum Disorders (FASD). The diagnosis of FASD requires recognition of children at risk, knowledge of the diagnostic criteria and confirmation of the diagnosis. Even the diagnosis of Fetal Alcohol Syndrome (FAS), the most visible condition in the spectrum in which there are characteristic facial features, is often missed. Facial abnormalities may not be recognised at birth, are most distinct in early childhood and may become less obvious in adolescents and adults. By definition, children with ARND or ARBD do not have all the characteristic facial features of FAS, making diagnosis more difficult than FAS. Furthermore, the behavioural and developmental problems associated with these diagnoses may not manifest until primary school age. Because data on maternal alcohol consumption during pregnancy are not routinely collected in Australia, there is the added difficulty of linking prenatal alcohol exposure with symptoms of ARND in the clinical setting or establishing a causal relationship. There are documented barriers to health professionals making the diagnosis of FAS, including lack of knowledge of the diagnostic criteria and reluctance to make the diagnosis of FAS/D for fear of stigmatising the mother, child and/or family (Payne et al. 2005; Elliott et al. 2006). Health professionals also express lack of confidence to manage with a child with FAS; lack of knowledge about where to refer children for confirmation of the diagnosis and management; and lack of proof of effective interventions (Payne et al. 2005; Elliott et al. 2006). Given these difficulties, it is important to use multiple datasets to provide more robust prevalence data wherever possible. To make a diagnosis of FASD, all children require a full developmental, physical, neuropsychological, language, hearing and visual assessment to identify their strengths and functional problems and inform referral for specialised intervention.

There are a number of ways in which the incidence and prevalence of FASD can be monitored. May and Gossage identified three main methods that have been used to determine the prevalence of FAS, Alcohol-Related Birth Defects (ARBD) and Alcohol-Related Neurodevelopmental Disorder (ARND): clinic-based studies (the most common method); passive systems; and active case ascertainment (May and Gossage 2001).

Clinic-Based Studies

Clinic-based studies are generally conducted in prenatal clinics of large hospitals where information is collected from pregnant women about their alcohol use. This may involve use of standard screening instruments and collection of biological specimens during pregnancy and some studies collect data at multiple time points. There are numerous standardised measures of alcohol use and evidence suggests the T-ACE (Tolerance, Annoyed, Cut Down, Eye Opener) (Sokol et al. 1989) and the TWEAK (Tolerance, Worry, Eye Opener, Amnesia, Cut Down) (Russell 1994) are most successful in identifying alcohol dependent women who may benefit from alcohol treatment interventions during pregnancy (Sokol et al. 1989; Russell 1994; Chudley et al. 2005). The AUDIT (Alcohol Use Disorders Identification Test), was not specifically developed to screen for drinking in pregnancy but includes questions related to frequency, quantity and binge drinking (Saunders et al. 1993). The AUDIT-C (a shorter version of the AUDIT that includes the three consumption questions) has been validated in pregnant women in the US but not in Australia (Dawson et al. 2005).

A recent systematic review of prenatal screening instruments to identify high risk drinking in pregnancy estimated that the TWEAK, T-ACE and AUDIT-C had the highest sensitivity in detecting risky drinking (Burns et al. 2010). The higher sensitivity comes at a cost of lower specificity (i.e. more false positives), indicating that for every woman identified correctly, as many as three women could be identified as drinking at risky levels when they are not. As these screening tools focus on high alcohol intake they may miss women drinking at low to moderate risk levels. It can, however, be argued it is more important to detect risky drinkers in this population. A recent Australian study recommended use of validated instruments such as the AUDIT-C as a rapid screening in clinical practice to assist with assessment and
management of alcohol consumption during pregnancy (Muggli et al. 2010).

Clinic-based studies have many advantages. Detailed maternal history data are collected (this can be done prospectively) and it is possible to study a large number of pregnancies involving various levels of alcohol exposure. However, there are also disadvantages. Firstly, women at highest risk for FAS children are less likely to attend prenatal clinics regularly, and many do not attend at all, making access to the very highest risk cases less likely. Secondly, many clinic-based studies have been carried out in publicly funded hospitals and clinics where disadvantaged populations pre-dominate. These studies may therefore overestimate the prevalence of FAS associated with disadvantage. Thirdly, since FAS is not generally diagnosed at birth, but between the ages of three and 12 years, these studies may further
underestimate the prevalence of FAS in studies where women are not followed up long term (May and Gossage 2001).

Passive Surveillance Systems

Some passive surveillance systems use existing record or data collections in a particular geographical area over a particular timeframe. This method involves researchers defining a set of criteria for diagnosis of FAS, ARBD or ARND and then looking for documented or probable cases of children born with the diagnosis. Records reviewed generally include: birth certificates, special registries for children with developmental disabilities or birth defects, and/or the medical charts of hospitals and physicians. Passive surveillance studies often use multiple types of records to identify as many cases as possible, since a case of FAS is often documented in more than one place over time. The major advantage of the passive method is that it uses existing records and it is therefore relatively inexpensive and easier to undertake than more time-intensive methods. The disadvantages are that FAS involves multiple indicators of physiology, development and behaviour, many of which are not obvious, or are at least difficult to identify at particular ages. Consequently the information required to make a diagnosis may not be recorded on these data systems, or may not be identified as related to prenatal alcohol exposure (May and Gossage 2001). Other passive surveillance systems rely on reporting of cases with pre-defined inclusion criteria by particular groups e.g. clinicians or midwives to particular databases e.g. birth defects registers in Australia. Data may be collected prospectively in this way but case ascertainment is lower than with active methods of ascertainment, even if reporting is mandatory.

Active Case Ascertainment Methods

One approach to active case ascertainment is to identify and recruit children with a possible diagnosis of FAS from large populations. Once identified, children are examined to determine the final diagnosis. In some studies, the children’s mothers are also recruited to collect information about maternal behaviour and risk factors. This type of active case ascertainment methods has at least three advantages. Firstly, the primary focus is on finding children with FAS at an age at which an accurate diagnosis can be made by clinical specialists. Secondly, the active and intense methods of recruitment mean a higher possibility of identifying children with FAS. Thirdly, by studying total populations, bias is reduced. Active case ascertainment therefore produces the most complete assessment of the prevalence and characteristics of FAS in a particular population. However, this method of research is very labour intensive, time consuming, and costly. Furthermore, access to particular populations may be selective and, frequently, only high-risk populations where FAS is more common have been studied using these methods. In this situation the prevalence of FAS may be overestimated (May and Gossage 2001). Another approach to active case identification is to target specialist groups, such as paediatricians and geneticists, who are likely to make the diagnosis of FASD and to use a reminder mechanism to prompt central notification of new cases on a regular basis. This method has been used nationally by the APSU to identify cases of FAS seen by paediatricians. This type of system provides timely, detailed, clinical data from which a minimum incidence rate can be estimated in the population of children seen by these health professionals.

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