To the Editor.—

The long-term effect of elevated total serum bilirubin (TSB) levels on neurologic outcome remains controversial. In 1993 we reported an analysis of data from the US Collaborative Perinatal Project, a cohort study of infants born 1959–1966 that included neurologic examinations at age 7 on 33 272 children. We found a statistically significant association between TSB level ≥20 mg/dL and “abnormal or suspicious” neurologic examination (22.4% vs 15.1%; P < .001), but no significant association between peak TSB level ≥20 mg/dL (342 μmol/L) and “abnormal” neurologic examinations (4.5% vs 3.8%; P = .66) at age 7 years.

Brown and Johnson and Johnson and Bhutani have speculated that the reason we found no association between TSB ≥20 mg/dL and definite neurologic abnormalities is that abnormalities were prevented by exchange transfusions, done in 53% of the infants with TSB ≥20 mg/dL. To examine this possibility,...

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