The effect of comorbidity on injury outcomes: developing and validating ICD-10 based injury comorbidity indices

Comorbidities are ‘other’ chronic diseases/conditions that exist alongside a ‘main’ disease or injury of concern. Pre-existing comorbidities are known to be associated with outcomes such as mortality, hospital-burden and in-hospital complications. This thesis derives a suite of outcome- and injury-specific comorbidity indices. The associations between comorbidities and outcomes vary depending on the outcome and the study population. Therefore, the newly derived indices are recommended for injury outcomes research compared to the frequently used existing comorbidity indices, which are not specific to each outcome and derived for general medical patients that include injury and non-injury patients.