No resurgence of kernicterus

Increased serum bilirubin, clinically manifest as jaundice, is very common during the first week of life, affecting around 60 % of full-term babies and 85 % of babies born prematurely. For the vast majority this neonatal jaundice is a mild transitory phenomenon with no long-term consequences. The greatest fear associated with neonatal jaundice is kernicterus. 

This condition (alternative name chronic bilirubin encephalopathy) is the result of the toxic effect of bilirubin deposition in brain cells, and only occurs if serum bilirubin rises to extremely high levels (>400-500 mmol/L). Kernicterus can be fatal; all survivors suffer permanent neurological deficit of variable effect and severity. 

Timely phototherapy guided by serum bilirubin monitoring prevents kernicterus so that it is a rare condition - but just how rare? There is a perception, reflected in the literature, that there was a resurgence of kernicterus during the 1990s following virtual eradication of the condition during the late 1970s and early 1980s after development of protocols for prevention of hemolytic disease of the newborn, once a major cause of kernicterus. 

Concerns about this presumed resurgence spawned a recent plethora of fresh national and local guidelines aimed at improving the effectiveness of neonatal jaundice monitoring. According to the authors of a recent Californian study, the evidence base for the supposed increased incidence of kernicterus during the 1990s is insubstantial. 

The results of their study now challenge the received wisdom. Their analysis of data from the Californian Department of Developmental Services revealed 25 cases of physician-diagnosed kernicterus for the period 1988-1997, show an annual overall incidence of 0.44 per 100,000 live births in California. There was no significant trend over the 10 years. 

This data from California is supplemented with analysis of national mortality statistics. For the period 1979-2006, a total of 31 kernicterus-related deaths were recorded throughout the US. Here again there was no significant time trend. The dual results of the study argue against the notion that there was a resurgence of kernicterus during the 1990s. 

Kernicterus has remained a very rare condition, affecting around close to four babies per million live births each year, over the past 25 years. The study also confirms the previous finding that there is a male preponderance of 3:1 among both incident cases of kernicterus and kernicterus-related deaths.