Appendicectomy, like smoking, is known to influence the clinical behavior of ulcerative colitis. However, in patients with coexistent primary sclerosing cholangitis (PSC), the phenotype of their disease already differs from those patients with ulcerative colitis (UC) alone.
Researchers have therefore examined the interaction of appendicectomy and PSC on the epidemiology and clinical course of ulcerative colitis, to see what further differences may be observed.
Patients from the Brisbane IBS Research Group database were used to carry out the study, with controls taken from the Australian twin registry.
A total of 78 PSC-inflammatory bowel disease (PSC-IBD) patients, 12 pure PSC patients, and 294 UC patients were matched with 1466 controls by sex and birth cohort that comprised randomly selected twins from each twin pair.
Investigations were then carried out into the effects of appendicectomy, smoking, or PSC on various clinical factors.
These were onset of disease, disease extent, disease severity (as identified by immunosuppression-colectomy or liver transplant) and disease related complications. Disease related complications were classed as high grade dysplasia, colorectal cancer, or cholangiocarcinoma.
All investigations were analyzed using univariate and multiple logistic regression analyses.
The researchers found that PSC-IBD patients suffered from more extensive colitis that did UC patients, but required less immunosuppression, a finding which was independent of disease extent.
Furthermore, such patients had an increased likelihood of having high grade dysplasia or colorectal cancer than did UC patients.
| Appendicectomy can influence ulcerative colitis
In the PSC groups there was no difference in appendicectomy rates when compared with the control group.
This contrasted dramatically with the UC patients, who were four times less likely to have undergone appendicectomy than were subjects from the control group.
When examining the affect of appendicectomy, there appeared to be an approximate five year delay in the onset of intestinal (PSC-IBD or UC) or hepatic (PSC) disease in those patients who had undergone prior appendicectomy. This finding was independent of smoking.
However, appendicectomy did not independently alter the extent or severity of disease in PSC.
This was not the case in UC, where prior appendicectomy was associated with more extensive disease but with a lesser requirement for immunosuppression or colectomy for the treatment of colitis.
Non-statistically significant trends for high grade dysplasia or colorectal cancer were identified with appendicectomy in both PSC-IBD and UC. Despite the lack of statistical significance, colorectal cancer appeared more frequent with appendicectomy in a meta-analysis of the available UC data from this and another Australian study.
The researchers conclude that unlike UC, appendicectomy did not significantly influence the prevalence of the PSC groups, or the extent of colitis in PSC-IBD. However, as with UC, appendicectomy did appear to delay their onset.
They add that extensive milder colitis, which is characteristic of PSC-IBD, relates to other poorly understood factors.
Further prospective studies, they say, are required to determine any influence of appendicectomy on the extent of colitis in IBD and an associated dysplasia or colorectal cancer.