The Effects of Pre-operative Depression and/or Anxiety on Length of Stay of Cardiac Surgical Patients
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Background: Previous literature has found mixed results concerning the relationship between depression, and anxiety, and length of hospital stay among cardiac surgical patients. Given the high prevalence of these psychiatric illnesses and cardiovascular disease in Canada, a better understanding of the relationship between these variables has the potential to influence medical and psychiatric outcomes for countless individuals. Objectives: The objectives of this manuscript style thesis are to (a) describe the prevalence of mild and moderate-to-severe symptoms of depression and anxiety disorders in a sample of cardiac patients (Manuscript 1) and (b) analyze the effects of these symptoms on post-operative length of stay while controlling for potential confounding variables (Manuscript 2). Methods: This secondary analysis used data collected from a consecutive series of consenting patients attending Foothills Hospital Pre-operative Assessment Clinic (August 1998-March 2002). Patients completed the Zung Self-Rating Depression and Anxiety scales, and a questionnaire assessing potential confounders. Manuscript 1: Prevalence values and 95% intervals were calculated for mild and moderate-to-severe depression and anxiety while logistic regression was used to determine predictors of these conditions. Manuscript 2: The relationship between symptoms of depression, anxiety and length of stay was analyzed using multiple linear regression. Results: Manuscript 1: We estimated that moderate-to-severe symptoms of depression and anxiety were present in 10.66% and 3.42%, respectively. Mild depression (21.90%) and anxiety (32.89%) were also present. Common predictors of both conditions included sex, general health, and a recent myocardial infarction. Depression was further associated with co-morbid illness, as was type of surgery with anxiety. Manuscript 2: Patients with depression experienced a significant increase in length of stay compared to mentally healthy patients. Age, general health, type of surgery and education also predicted hospital stay, while anxiety did not. Conclusions: Manuscript 1: The prevalence of depression and anxiety in our sample demonstrates the need to address the burden of psychiatric illness in this population. Predictors of these disorders may assist in determining risk groups that would benefit most from psychiatric testing and interventions. Manuscript 2: The elevated length of stay observed among patients with depression supports the implementation of screening and treatment in this population.