In the last epidemiological study of appendicitis in Scotland (Bisset AF. Appendicectomy in Scotland: a 20-year epidemiological comparison. J Public Health. 1997 Jun 1;19(2):213-8), 1522 appendicectomies in 1993 were performed in children aged 0-15 years old. This suggests that a 10 year cohort should be more than adequate to detect a clinically significant difference in length of stay.