Table 2.

Quality improvement procedures undertaken in Wisconsin to improve CF newborn screening

The IRT assay was changed from a radiometric to a fluorescent dissociation enhanced lanthanide fluorescence immunoassay method

A “floating” IRT referral level for DNA testing was introduced to minimize seasonal effects on measured IRT levels

The IRT referral level for DNA testing was decreased from the 98.5th to the 94th percentile; this was later revised up to the 96th percentile to minimize carrier detection

DNA testing was performed 3 days per week (increased from 1 day per week previously)

DNA detection changed from F508del only to routine screening for the American College of Medical Genetics (ACMG) 25 CF transmembrane conductance regulator (CFTR) mutations using a strip detection system (CF-Gold LAp, Roche Molecular Biochemicals) in March, 2002. When R117H is detected, re ex testing for the polythymidine tract in intron 8 (5T, 7T, and 9T) is performed. In July 2008, the screening changed to the ACMG 23 CFTR mutations using the Invader® Assay (Hologic Inc.)

Infants with IRT levels higher than the 99.9th percentile but without detectable CFTR mutations are reported as “possible” abnormal. Sweat testing is recommended when there are symptoms or a positive family history.

As a quality control measure, the Wisconsin State Newborn Screening lab routinely analyzes specimens with abnormal results in a blinded fashion to ensure repeatability of results

The Wisconsin State Newborn Screening lab implemented a formal process to follow up on all abnormal results to maximize the likelihood that a follow up sweat test would be performed

Primary care providers are notified by phone by the Wisconsin State Newborn Screening lab when two disease-causing mutations are identified

Sweat tests are scheduled as soon as possible, as long as the infant weighs at least 2.95 kilograms.

In 2005, sweat tests were made available at an affiliate CF Centre to decrease the distance some patients had to travel