Cystic Fibrosis Screen Positive, Inconclusive Diagnosis (CFSPID): A new designation and management recommendations for infants with an inconclusive diagnosis following newborn screening

Background: Newborn screening (NBS) for cystic fibrosis (CF) results in the recognition of a number of infants with a positive NBS result, but an inconclusive diagnosis. Varied practice exists with respect to the management of these infants.

Methods: A Delphi consensus approach was used to determine agreement on statements generated by a core group of specialists. A designation (naming) exercise was required after Round 1 and further expert opinion was sought to guide that process. After Round 2, a sensitivity analysis was undertaken to assess the impact of attrition on subsequent agreement levels.

Results: Infants were divided into group A (normal sweat chloride and two CFTR mutations, at least one of which has unclear phenotypic consequences) and group B (intermediate sweat chloride and one or no CFTR mutations). 32 statements were produced for Round 1 and 24 achieved consensus. After Round 1, a designation exercise was undertaken and the term "CF Screen Positive, Inconclusive Diagnosis (CFSPID)" was suggested for Round 2. Agreement was achieved for this statement and for all other statements aside from the need for routine respiratory culture, on which there was divided opinion. The core group advocated local practice for this issue. A sensitivity analysis demonstrated that consensus for Round 2 was achieved by change in opinion rather than attrition.

Conclusion: We have generated a new designation and statements to guide the management of infants with CFSPID through a robust international Delphi process. These statements will be a valuable tool for CF teams and will improve the consistency of management of these infants.