Predicting outcomes of acute myocardial infarction using administrative data: Is depression associated with survival

Study objectives. This dissertation investigated three main issues: Determination of the most appropriate risk-adjustment method to control for comorbidity when predicting mortality following acute myocardial infarction (AMI); whether depression following AMI is associated with important prognostic factors such as comorbidities; and whether early- and late-onset incident depression following AMI affect short- and long-term survival and health services use.; Methods. Data. The British Columbia (BC) Linked Health Database, which includes all hospitalizations, drug prescriptions, physician visits and deaths in BC. Participants A cohort of 4874 individuals aged 66 years and over who had an AMI in 1994 or 1995. Analysis. Risk-adjustment methods were compared using the C-statistic; Chi-square and Kruskal-Wallis analyses were used for testing associations between depression and prognostic factors; logistic regression analyses were used to measure the relationship between depression and health services use; Kaplan Meier and Cox regression analyses were used for determining the effect of depression on survival following AMI.; Main findings. A risk-adjustment method developed specifically for predicting mortality following AMI (the Ontario AMI predictive rule) was found to be a more appropriate method than more general methods of predicting mortality (e.g., the Charlson Index). Depression following AMI was associated with an increase in comorbidity. Both early- and late-onset incident depression following AMI significantly increased short- and long-term mortality, and is one of the strongest predictors of mortality following AMI in older adults. Depression was not found to be associated with increased health services use.; Conclusions and significance. This was the first study to investigate the impact of depression following AMI using administrative data. Early- and late-onset depression following AMI significantly affects survival, however it does not affect health services use. In contrast to previous research, in this study incident rather than prevalent depression was measured as well as depression occurring up to 5 years following AMI, and not only at the time of or shortly after the index hospitalization. The relationship between depression and comorbidity was investigated which has not been previously done. Future research should focus on determining effective treatments for individuals with depression following AMI.