Response to Astley’s Letter to the Editor

Editors of Alcohol: Experimental and Clinical Research

Thank you for the opportunity to respond to Dr. Astley’s Letter to the Editor concerning our recent paper (Coles, Gailey, Mulle, Kable, Lynch & Jones, 2016). As we stated in that paper, the study’s purpose was to examine the methods used in the diagnosis of Fetal Alcohol Spectrum Disorders (FASD) as a way of understanding the extent to which these methods were consistent with one another and to suggest areas in which further research on diagnostic methods would be profitable. We undertook the study as we felt that there is a need for a clear and consistent method for diagnosis of FASD that is widely “accessible” to clinicians. It is important to understand that there was no intention of criticizing any system or of selecting any as the more reliable as we do not believe that the current state of the field allows such a decision.

Dr. Astley raised two points in her letter. Both result from specific methodological choices that we felt were required due to limitations created by the methods specified by the systems themselves and by the nature of this clinical data. The first issue was that in sorting cases into diagnostic categories, we did not use the same criteria for pFAS that the 4-Digit Code recommends (Astley, 2004). To allow consistency in the comparison of systems, we defined the categories of FASD used in the paper according the methods suggested by the Institute of Medicine (IOM; Stratton, et al, 1996). The 4-Digit Code does not define their results in the same way and this method results in 22 categories. We used the 4-Digit code instructions to create these 22 categories. Then, In order to make the comparisons in the paper, we collapsed these 22 categories into those 4 defined by the IOM and used by the other systems. We regret that Dr. Astley does not agree with our methods for doing this. However, we believed that the purpose of the analysis was best served by this approach.

Dr. Astley’s second question concerns the norms used for palpebral fissure length (PFL). Although Dr. Astley recommends the use of the Iosub, et al (1985) data as norms for African-Americans, after careful consideration of that study, we did not feel that we could follow that suggestion based on our understanding of their validity. Because, the 4-Digit diagnostic guide, (Astley, 2004), states first, that “Normal PFL charts adjusted for race should be used if available and confirmed valid” and later, that “Other valid growth charts may be used”, we chose to use the Scandinavian (Stromland, et al., 1999) norms. We invite those concerned about this issue to review the Iosub, et al. (1985) paper themselves and make their own judgement of this question.

In summary, this was a complex analysis that required us to make a number of methodological decisions in order to map the abstracted clinical data on to the requirements of the 5 diagnostic systems that were compared. We understand that there may be disagreements about our choices and we were happy to discuss these and the reasons for our decisions. We hope that future discussions of these data can focus on ways in which the field can improve validity and consistency in the diagnosis of FASD across the many different sites in which such diagnoses occur.