Age at appendicectomy

Summary: Bivariate survival data: twin age-at-appendicectomy from questionnaire survey of adult members of the Australian NHMRC Twin Registry.

In the period from November 1980 to March 1982 a questionnaire was mailed to the 5967 pairs of twins over the age of eighteen years registered with the Australian Council Twin Registry by Drs Nick Martin and John Mathews. Of this group, 3808 twin pairs returned completed questionnaires (a pairwise response rate of 64% - Table 13.1)

Included on the questionnaire was an item on whether twins had undergone surgery, including age at operation. The data set under discussion consists of the response to the sub-item on appendicectomy. A number of cases were suspected to be prophylactic appendicectomies because they occurred in the same year as other procedures such as cholecystectomay and hysterectomy. These have been excluded. Nevertheless, since we are unaware of the operative findings, a large number of unnecessary appendicectomies are undoubtedly included in the data. These might be expected to occur more frequently in females, because women are more likely to suffer abdominal pain due to a variety of causes.

The original citation for these data is:

Duffy DL, Martin NG, Mathews JD (1990). Appendectomy in Australian twins [Letter]. American Journal of Human Genetics; 47(3): 590-592.

See also:

Dabrowska DM, Duffy DL, Zhang ZD (1999). Hazard and density estimation from bivariate censored data. Journal of Nonparametric Statistics 10: 67-93.
Fan J, Hsu L, Prentice R (2000). Dependence estimation over a finite bivariate failure time region. Lifetime Data Analysis 6: 343-355.
Kooperberg C (1998). Bivariate density estimation with an application to survival analysis. Journal of Computational and Graphical Statistics, 7 322-341.
Prentice RL, Hsu L (1997). Regression on hazard ratios and cross ratios in multivariate failure time analysis. Biometrika 35: 25-39.

We have also published analyses incorporating additional information on covariates such as cigarette smoking:

Oldmeadow C, Wood I, Mengersen K, Visscher PM, Martin NG, Duffy DL (2008). Investigation of the relationship between smoking and appendicitis in Australian twins. Ann Epidemiol. 18: 631-636.

And also incorporated genetic linkage information into the model:

Oldmeadow C, Mengersen K, Martin N, Duffy DL (2009). Heritability and linkage analysis of appendicitis utilizing age at onset. Twin Res Hum Genet. 2009 Apr;12(2):150-7.