The usefulness of CRP and I/T ratio in early diagnosis of infections in Asian newborns.

The greatest challenge in neonatal infection is to correctly identify an infected neonate and not to overtreat those who are not. We studied 80 Asian neonates suspected of sepsis. C-Reactive Protein (CRP), Total White Cell Count (TW) and Immature to Total Neutrophil Ratio (I/T ratio) were evaluated in terms of their specificity, sensitivity, positive and negative predictive values. CRP was measured quantitatively by Fluorescence Polarisation Immunoassay Technology (FPIT). There were 36 positive cases (positive blood culture or Chest Radiography [CXR] showed pulmonary infiltrates). Using the FPIT, CRP in 98% of clinically healthy individuals is (less than or equal to) 1.0mg%. When CRP is less than or equal to 1.0mg% is taken as norm, its specificity range from 0.84-0.91 and its sensitivity from 0.22-0.50. However, CRP may be marginally raised in conditions of stress like birth asphyxia and fetal distress. Thus when CRP less than or equal to 1.5mg% is considered as norm, its specificity range from 0.93-1.00 and its sensitivity from 0.14-0.33. The positive predictive value range from 71%-100% and the negative predictive value from 57%-63%. The normal I/T ratio is less than 0.2. The specificity of I/T range from 0.75-0.91 and the sensitivity range from 0.22-0.47. The positive and negative predictive values range from 60%-76% and 58%-66% respectively. Hence CRP is very specific especially when it is less than 1.5mg% but not as sensitive. I/T although less specific is also more specific than sensitive. Combining CRP and I/T as a marker of sepsis only increases its specificity (range 93%-100%) but not its sensitivity (range 16%-45%).(ABSTRACT TRUNCATED AT 250 WORDS)