Rebound bilirubin: on what should the decision to recommence phototherapy be based?

I read with great interest the recent paper by Kaplan et al about post‐phototherapy bilirubin rebound. The incidence of significant rebound bilirubin was reported as 13.3% (30/226); the large number of neonates who rebounded (26/30) were among those in whom phototherapy had been commenced ⩽72 hours.¹ We have conducted a similar study with a total of 375 newborns; the proportion of neonates with significant rebound bilirubin who required phototherapy was 5.1% (19/375); 16 of 19 were from the birth hospitalisation group (⩽48 hours).² The key factor to take into consideration (which is not standard and limits the value of evaluation of studies for meta‐analysis or comparison), is the definition of rebound bilirubin level that may be presumed for reinstitution of phototherapy. Kaplan et al recommenced phototherapy at bilirubin values >256 μmol/l; their decision to reinstitute phototherapy was influenced by the presence of risk factors for hyperbilirubinaemia.¹ In our study, we used charts which were recommended by the American Academy of Pediatrics³ as in their study, but recommenced phototherapy if the rebound bilirubin level was above the value which was appropriate for the patient's age and risk factors. This is of importance as the accepted level for reinstitution of phototherapy cannot be assumed to be similar for birth hospitalisation or readmission groups, depending on the age of the patients. This difference may explain the higher incidence rate reported by Kaplan et al than in the other large series.²,⁴ If a standard design is used for reinstitution of phototherapy, routine measurement of bilirubin levels after termination of phototherapy in infants, regardless of low birth weight, prematurity, and positive direct Coombs' test result, may not be required, as it was in our study.