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Risk factors affecting adverse outcomes of cardiac surgery in patients aged 70 years and older.

BACKGROUND
The elderly segment of the population in Taiwan is increasing rapidly. According to the latest information from the Directorate-General of Budget, Accounting and Statistics, Executive Yuan, Taiwan, 1,553,367 civilians of the total population of 22,879,510 (6.8%) are seventy years old and older in 2007. The proportion of high-risk patients has increased dramatically owing to a greater number of elderly patients and increased number of average patients with heart diseases presenting for cardiac surgery. We analyzed the preoperative risk factors for in-hospital mortality, morbidity and the likelihood of prolonged intensive care unit (ICU) stay in elderly patients after cardiac surgery.


METHODS
We retrospectively studied 952 adult patients who received cardiac surgery during a three-year period (from August 1, 2004 to December 31, 2006) at Taichung Veterans General Hospital. Patients were divided into a control group and a study group. The study group (n=395) exclusively consisted of patients aged seventy or over while the rest of the patients under study served as reference group (n=557). Continuous variables were compared using Student's t test, and categorical variables were compared using Pearson chi-square test. Variables associated with in-hospital mortality, major morbidity and prolonged ICU stay in univariate analysis with P < 0.05 were entered into multivariate analysis using logistic regression with a stepwise forward selection procedure to determine independent variables and identify variables associated with major adverse outcomes.


RESULTS
Fifty-six (14.2%) patients died during their hospitalization in the study group and 46 (8.3%) in the reference group. Major mortality in the study group was 58.0% versus 39.7% in the reference group. The patients of the study group spent more days in the ICU than did patients of the reference group (8.7 +/- 12.0 versus 6.1 +/- 10.0 days, P < 0.05). In addition, 114 (28.9%) patients of the study group and 85 (15.3%) of the reference group spent more than 7 days in the ICU. Using multiple logistic regression analysis, risk factors affecting in-hospital mortality in the study group include impairment of renal function, reoperation, congestive heart failure (CHF), catastrophic event. Impaired renal function, complexity of surgical procedure, CHF, chronic obstructive pulmonary disease (COPD) and catastrophic state were significant factors affecting morbidity in the study group. CHF, COPD and catastrophic event contributed to prolonged ICU stay in the study group.


CONCLUSIONS
The perioperative risk of cardiac surgery increases in older patient groups, and some risk factors have different influences on mortality, morbidity and ICU stay. Risk assessment in older cardiosurgical patients with convenient risk factors helps the clinicians to apply rational and cost-effective treatment strategies into practice.