Table 2

Performance indicators of the UK NBS protocol for CF in the West Midlands

Performance indicator*Sensitivity† (%)Specificity (%)PPV‡ (%)CF:carrier§CF:CFSPID
97.1>99.966.71.2:18.1:1
  • *Performance indicators were chosen in line with published consensus document.16

  • †Babies with meconium ileus were not included as false negatives in the sensitivity calculation.

  • ‡Infants designated as CFSPID were included as false positives in the PPV calculation.

  • §Refers to individuals identified as a ‘probable carrier’ via the NBS protocol and those diagnosed as a carrier at the CF centres after being referred as ‘CF suspected’.

  • CF, cystic fibrosis; CFSPID, CF screen positive, inconclusive diagnosis; NBS, newborn bloodspot screening; PPV, positive predictive value.