FAS Surveillance: The Numbers Game

In a recent government publication (MMWR weekly, May 24, 2002/51(20);433-5), the Centers for Disease Control and Prevention issued a report on their 5-year FASSnet surveillance project in four states (Alaska, Arizona, Colorado, and New York). This report states that the over-all prevalence rate for FAS in these four states from 1995-1997 was between 0.3 to 0.4 per 1,000 live births. The report from FASSnet (Arizona's CDC team) indicates that the prevalence of FAS in the state of Arizona in 1998 was .13 per 1,000 live births.

There are two reasons for the wide variation in numbers among the different studies that have been conducted. One is the difference in qualifying criteria to be met in order to be counted, and the other is the method of counting. For those who would like an in-depth explanation, I highly recommend reading the Institute of Medicine's 1996 Report to Congress and Phil May's article on prevalence. These two documents describe the different methods of surveillance and their drawbacks.

I participated on the workgroup for the project in Arizona, and I believe that the numbers reflect only data derived from examining medical records like the Arizona Birth Defects Registry. (Doctors are not currently required to report FAS or suspected FAS in the Birth Defects Registry.) In order to qualify and be counted in the CDC surveillance study, these cases must meet strict criteria developed to ensure uniformity. The surveillance numbers are good for tracking trends, but do not reflect actual numbers of children who are adversely affected.

The CDC uses diagnostic criteria defined in the Institute of Medicine's 1996 report to congress. The IOM report's executive summary states the following: "Although passive surveillance is relatively inexpensive, it is notoriously inaccurate; given that FAS is a complex diagnosis, it may go unrecognized at birth. Thus, registry-based estimates of FAS prevalence can be expected to be gross underestimates."

I think it is important to mention another fact that is stated in the IOM report: "Many prenatally-exposed individuals do not receive correct diagnosis or treatment for their alcohol-related disabilities." Most of the families who receive support and information from the FAS Community Resource Center are caring for children who do not have a formal diagnosis, and only one of those individuals who has a diagnosis of FAS was diagnosed before age 3. That individual is my son John, and the only reason he received a diagnosis at birth was because he happens to be at the far end of the FAS spectrum with just about every possible symptom, and the doctors at the Denver hospital where he was born were recently trained in FAS.

Most doctors cannot recognize FAS, most doctors don't know how to diagnose FAS, and most doctors do not ask their pregnant patients about alcohol use. And most cases of FAS are not recognized until the child enters school and the neurological dysfunction becomes more obvious. So you can see how the surveillance figures based on medical records of infants and toddlers under the age of five will not reflect actual numbers. As for the full spectrum of FAS disorders, we don't really know how many children are adversely affected enough to be counted because there is no system developed to determine this number. Streissguth's studies probably come closest to determining the prevalence of all FAS disorders on the spectrum of ARND, and her studies indicate the number to be approximately 1 in 100 live births. (Teratology 1997 Nov;56(5):317-26). Here are the figures cited by SAMHSA (the National Clearninghouse on Alcohol): "The incidence of Fetal Alcohol Syndrome (FAS) has been estimated at 1 to 3 per 1000 live births. Fetal Alcohol Spectrum Disorders (FASD) (which include FAS) are estimated to occur in about 1 in 100 births."

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Institute of Medicine Chapter 5: Epidemiology and Surveillance
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