The relationship between appendectomy and Crohn's disease is controversial.
Dr Morten Frisch and colleagues from Sweden conducted a Swedish-Danish cohort study to assess the risk of developing Crohn's disease after an appendectomy.
The team followed up 709,353 appendectomy patients in Sweden and Denmark for first hospitalizations for Crohn's disease from 1964 to 2004.
Standardized incidence ratios served as relative risks.
|The standardized incidence ratio of developing Crohn's was 1.5|
The team reported there were 1655 Crohn's disease cases during 11 million person-years of follow-up.
The research team found that appendectomy before the age of 10 years was not associated with the risk of Crohn's disease.
The overall standardized incidence ratio of developing Crohn's disease was 1.5, being highest in the first 6 months.
Standardized incidence ratios diminished rapidly thereafter, with the risk of Crohn's disease reaching background levels after 5 to 10 years for Crohn's disease overall.
The team observed that the standardized incidence ratios also reduced for Crohn's ileitis, ileocolonic Crohn's disease, Crohn's colitis and other Crohn's diseases.
A long-term increased risk of Crohn's disease up to 20 years after the appendectomy was seen only in appendectomy patients without appendicitis or mesenteric lymphadenitis.
Dr Frisch's team concluded, "The transient increased risk of Crohn's disease after an appendectomy is probably explained by diagnostic bias."