Chest Radiographs for Distinguishing ADA-SCID from Other Forms of SCID

J Clin Immunol 2020 Feb;40(2):259-266. doi: 10.1007/s10875-019-00733-1.

PMID: 31858364

Martijn V Verhagen, Valentina Trevisan, John Adu

Highlights: Radiological features such as scapular spurring, scapular squaring and costochondral cupping can reliably differentiate between ADA-SCID and other forms of SCID.

Abstract

Purpose: Early separation of adenosine deaminase deficient severe combined immunodeficiency (ADA-SCID) from other kinds of SCID may allow for the implementation of suitable therapy measures aimed at metabolic detoxification and improved outcomes. Our hypothesis was that radiographic markers such as inferior scapular angle squaring and spurring, as well as costochondral cupping, may distinguish ADA-SCID from other types of SCID.

Methods: Chest radiographs of children with ADA-SCID taken at clinical presentation between 2000 and 2017 were retrospectively included if the radiological characteristics were assessable. For comparison, random chest radiographs of children with various types of SCID were included. Three pediatric radiologists (2 senior, 1 junior) evaluated the radiographs for particular radiological findings and diagnosed them (ADA-SCID or non-ADA-SCID). A ROC curve was used to determine the best test performance threshold.

Results: Thirty-six ADA-SCID patients and twenty-five non-ADA-SCID patients were included in the study (median age 3.8 months). The optimal test performance threshold was at approximately < 7 months old: 91.7% sensitivity, 80.7% specificity, k = 0.709 interreader agreement, and AUC 0.862. Scapular squaring, scapular spur, and costochondral cupping all had positive likelihood ratios of 4.0, 54.6, and 7.8, respectively. The test was valid when performed by both senior and junior pediatric radiologists.

Conclusion: Scapular spurring, scapular squaring, and costochondral cupping are radiological characteristics that can consistently distinguish ADA-SCID from other forms of SCID. This is true for children under the age of seven months, and it is confirmed by both senior and young pediatric radiologists.

Keywords: ADA-SCID, ERT, HSCT, SCID, diagnosis, radiograph