In their article, "Long-term Outcome After Severe Brain Injury in Preschoolers Is Worse Than Expected,"1 Koskiniemi et al are to be congratulated for their extraordinarily long-term follow-up of a sample of head-injured children. They report that functional outcome in adults who had sustained head injuries as children is "worse than expected." The title implies a comparison group, but the article reports outcomes only for children with head injuries who were subsequently referred for rehabilitation. Selection of only these individuals for follow-up would bias the sample toward those with poor outcomes. We therefore wonder if "worse than expected" outcomes are a result of selection bias, failing to account for other children who sustained head injuries of similar severity during the study period and who fully recovered with no rehabilitation referral.
Koskiniemi et al further report that "The final outcome (of traumatic brain injuries [TBIs]) was worse in the children who