A database of incident reports from the Ontario School Board
Insurance Exchange was used to identify all injury events occurring
at TDSB schools between January 1998 and December 2002
inclusive. Information in the database is provided by school staff
whenever an incident occurs in the school during school hours.
The threshold for completing a report is “whenever medical or
dental attention is required,” and this includes injuries attended
to by teachers or school staff, as well as those in which the child
went home or to a health facility. We included all injuries to children
4–11 years of age that occurred within the school playground.
Research assistants, blinded to the study purpose and
date of injury (i.e., before or after equipment removal), coded all
playground incidents on the basis of written descriptions from
the database. Injuries where equipment was explicitly mentioned
in the written description were flagged as “equipment related”
for subanalysis.
Expected post-intervention injury rates in the intervention
schools were calculated by multiplying the pre-intervention rates
in intervention schools by the ratio of post-intervention to preintervention
rates in the nonintervention schools. The proportion
of injuries prevented (etiological fractions)14 were calculated by
subtracting observed from expected rates and expressing the result
as a percentage of the expected rate. The analysis was repeated for
the subset of injuries flagged as equipment related.