[CIS PIDD] [cis-pidd] Follow-up of abnormal NBS for SCID in preterm infants

[Monica Lawrence]

The state of Virginia implemented newborn screening for SCID on June 4th.  In these early weeks, we are seeing a lot of abnormal screens even in term infants, which is likely due to assay cut-offs that need to be adjusted; the state lab is aware of this issue and working to do this.  In addition, we are seeing a lot of abnormal screens in preterm infants, as would be expected based on the published experiences out of several other states, including CA and WI.   The rate of abnormal screens is on the order of 7-8 per day from what the state lab has told me; we were expecting 20-30 abnormal screens per YEAR.  

I am hoping for the advice of others in states who have already implemented NBS, as we work to develop our institution-specific protocol for follow-up of abnormal newborn screens for SCID in preterm infants.  Specifically, I am hoping for your answers to the following questions.  

1 -  I am aware of the published guidance about repeating the TREC assay every 1-2 weeks until normal or until 37 wks GA (whichever comes first), followed at that time by flow cytometry if persistently abnormal (or sooner if clinically there are worrisome signs for SCID). Is it the practice at your programs to screen with (a) just a repeat TREC or (b) the whole NBS panel every 1-2 wks until 37 wks GA or until normal?  The issue with doing a repeat TREC alone is that it will be done at a different reference lab and so the values cannot be cross-compared directly with those generated by the state lab, and is an additional cost to the patient/hospital.  The issue with doing the whole NBS panel again is that, while free of charge to the patient/hospital and allowing for longitudinal analysis, there is the possibility of then having other abnormal screens be generated which require follow-up with potentially expensive tests (e.g. amino acid abnormalities).

2 - Our NICU team is questioning the utility of getting the repeat tests every 1-2 weeks in preterm infants (which if abnormal, will be attributed to being preterm most likely) vs simply waiting to repeat at 37 wks?  This becomes an issue particularly when a baby is VERY pre-term (e.g. 24 wks)

Thanks very much for sharing your experiences.

Monica


Monica G. Lawrence, MD
Assistant Professor of Medicine and Pediatrics
Division of Asthma,Allergy & Immunology
University of Virginia
PO Box 801355
Charlottesville, VA 22908
434-243-6811
ml4nz at virginia.edu








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