Prevalence of appendectomy in Japanese families.

We investigated the prevalence of appendectomy in Japan to determine the tendency of familial aggregation on appendicitis using a large scale study. A total of 517 Japanese women (aged 20 to 45 years) served as the subjects and were questioned regarding their family history of appendectomy due to appendicitis. We compared the prevalence of appendectomy in children (subjects+their siblings) of three groups of families: (i) both parents affected; (ii) one parent affected; (iii) no parents affected. The differences between groups were statistically significant using contingency table and Chi-squared test. Our results suggest that about 40% of children with both parents affected, and about 20% of children with one parent affected may develop the disorder during childhood. This study may provide useful information in the nature of the development of appendicitis.