ABSTRACT
There are various reasons for considering multiple disease distributions. First, the common etiology links could be thought to exist between the diseases and in the spatial patterning of the diseases. Second, disease progression could be represented by the separate diseases. Third, it could be that the links between diseases are to be explored and as yet unknown. An example of the first situation would be examination of diseases commonly affected by air pollution, such as respiratory cancer, bronchitis, asthma. This chapter focuses on the association between asthma incidence and that of chronic obstructive pulmonary disease (COPD) and angina. Both asthma and COPD are respiratory diseases, while angina is a coronary artery condition. It is possible to consider a truly multivariate model for the effects between the diseases. Such a model assumes a multivariate distribution for the underlying disease variation. It also provides for an inter-disease correlation, which is a summary measure of similarity between the diseases.
