Is the enemy from within?1, 2

Abstract

Andersson et al. conducted a population-based case-control study to assess the relationship between appendectomy and the development of ulcerative colitis (UC). All patients in Sweden with hospital discharge diagnoses that included appendectomies between 1964 and 1993 were identified from the national Inpatient Register. Only those who were younger than 50 at the time of surgery were included. Patients were divided into groups according to their discharge diagnoses, which included perforated appendicitis, nonperforated appendicitis, nonspecific abdominal pain, and mesenteric lymphadenitis. Community controls without histories of appendectomies were matched in a 1:1 fashion based on age, sex, and township of residence. Patients were excluded if they had diagnoses of UC at or before appendectomies, UC was diagnosed within 1 yr after the appendectomy, or there was less than 1 yr of follow-up.