Many efforts are underway to develop chronic disease management programs, but the majority of them focus on single chronic diseases and do not recognize the presence of co-morbidity (suffering from more than one condition) for many individuals with chronic disease. (University of British Columbia)

Identifying preventable risk factors may allow clinicians to decrease these unfortunate events. In order to perform appropriate statistical analyses, measures of important environmental exposures are needed because these are known to substantially increase exacerbation risk, including co-morbidity, medication use, tobacco smoking history and smoking status. (BioMed Central Ltd)

While the data in some areas of co-morbidity are stronger than in others, relatively little is known about the risk factors that increase the probability of co-morbidity or the protective factors that decrease its probability. (National Institute of Mental Health )