Appendectomy and asthma: a search for an association in older subjects

Introduction: Studies have shown an association between appendicitis and immune mediated diseases such as ulcerative colitis and multiple sclerosis. Asthma, like the diseases mentioned, is also an immune mediated disease, and hence could possibly be linked to acute appendicitis. In this study, we aim to explore the association between asthma and appendicitis, using appendectomy as a marker for appendicitis.

Individuals 40 years and older with asthma were recruited from an online patient database from UiTM Medical Centers at Selayang and Sungai Buloh. The subjects were interviewed face to face or by telephone. Patients with a history of appendectomy were identified and prevalence of appendectomy was then compared to that of controls of similar age group. The diagnostic criteria from National Asthma Education and Prevention Programme were used to identify individuals suffering from asthma. Controls were sampled from the general population. From both control and asthma groups we excluded persons who knew that their appendix had been histologically normal, and those who had undergone appendectomy as part of some other procedure. Individuals suffering from respiratory diseases other than asthma were also excluded, to prevent confusion of diagnosis.

Twenty-five of the 235 asthma patients had a history of appendectomy (10.6%). Of 1245 controls, 70 had a history of appendectomy, giving an overall prevalence of 6.3%. Gender did not vary in the appendectomy/ no appendectomy groups. Malay subjects had a lower prevalence of appendectomy (3.6%), while Indian subjects had the highest prevalence (13.5%). After partialing out the effects of ethnicity by logistic regression, the adjusted odds ratio between asthma and control subjects was 2.040 (95% CI: 1.216 – 3.420, p = 0.007). This shows a statistically significant association between asthma and appendectomy in this population.

A positive association exists between asthma and appendectomy in a population of subjects 40 years and older. This association is similar to that seen with multiple sclerosis but is the opposite to that seen with ulcerative colitis. The cause of this association needs study, particularly the possibility that an altered microflora has a role to play in mediating both conditions.