Early Diagnosis Improves Survival of Neonates With SCID

Neil Osterweil

January 27, 2011

January 27, 2011 — A diagnosis of severe combined immunodeficiency (SCID) at birth, followed by a hematopoietic stem cell transplant (HSCT), significantly improves an affected child's chance of survival compared with siblings with SCID diagnosed later in life, say investigators in the United Kingdom in a report published online today in Blood.

A retrospective review of data from 2 UK transplant centers shows that the transplant-related mortality rate of children diagnosed with SCID at birth was 8.5% compared with 38.7% for siblings or relatives with a late diagnosis of SCID. Overall survival was 90% vs 40%, respectively, report Lucinda Brown, RN and clinical nurse specialist, from the Department of Clinical Immunology at Great Ormond Street Hospital in London, United Kingdom, and colleagues.

"This report shows that in comparison to the presenting sibling, SCID babies diagnosed at birth have a significantly decreased number of infections, are transplanted earlier and have a dramatically improved survival outcome after HSCT regardless of the donor match, conditioning regime and SCID type," the researchers write.

The findings suggest that screening for SCID could help protect infants from fatal respiratory infections and allow for early transplant, the authors say.

The investigators looked at 2 cohorts of children with SCID: a sibling cohort of 60 who were diagnosed at their births from 1982 to 2010 because of a diagnosis of SCID in a sibling or other family member, and a proband cohort of 48 family members, primarily siblings, who presented with SCID from 1979 through 2009.

The median age at diagnosis was the day of birth (range, 0 - 29 days) for the sibling cohort compared with 143.5 days (range, 1 - 455 days) for the proband cohort (P < .001).

The authors found that 17 (35.4%) of 48 patients in the proband group died before allogeneic transplant, and that infection was the cause of death among all cases for which data were available. In contrast, only 1 of 60 children in the sibling cohort died — the family had refused transplant, and the child died from an infection.

Twelve (38.7%) of the 31 probands who went on to HSCT died from transplant-related causes vs 5 (8.5%) of 59 children in the sibling cohort who underwent either HSCT or gene-replacement therapy. One child in the sibling group received gene-replacement therapy rather than HSCT. The difference in transplant survival rate between probands and siblings was significant (P < .001).

When the authors looked at transplant-related factors, they found that 5 of 11 probands who received HSCT with an unconditioned regimen died compared with only 10% of siblings (P < .05). In addition, 2 of 7 probands who received reduced-intensity transplants died compared with none of 20 siblings who received the same type of regimen (P < .05). A higher percentage of probands who underwent myeloabaltive regimens died, but this difference was not statistically significant.

"These data show that the improved survival is a result of improved survival both before and after HSCT[,] and after HSCT is seen irrespective of donor choice, conditioning regime used or underlying diagnosis. It is highly likely that the improved survival relates to the ability to make an early diagnosis, thereby protecting infants from infection and secondary organ damage and improving nutritional status, and therefore allowing an improved ability to withstand HSCT," the authors write.

The authors have disclosed no relevant financial relationships.

Blood. Published online January 27, 2011.

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