This line is the one that interests me,
Over one year we conducted a case-control study in which the case patients were 235 persons with head injuries received while bicycling, who sought emergency care at one of five hospitals.
How many people did not go to hospital because a helmet helped prevent injury?
.......and failed to give figures of other head injury admissions!
Thornhill in Glasgow showed that when you look at ALL admissions cyclists don't even figure as a significant group