Article
Long-Term Mortality After Pneumonia in Cardiac Surgery Patients: A PropensityMatched Analysis
Journal of Intensive Care Medicine 1-7 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/0885066614523918 jic.sagepub.com
J. Iban˜ez, MD, PhD1, M. Riera, MD, PhD1, R. Amezaga, MD1, J. Herrero, MD1, A. Colomar, MD1, C. Campillo-Artero, MD, PhD1, J. I. Saez de Ibarra, MD2, and O. Bonnin, MD2
Abstract Background: The role that intensive care unit (ICU)-acquired pneumonia plays in the long-term outcomes of cardiac surgery patients is not well known. This study examined the association of pneumonia with in-hospital mortality and long-term mortality after adult cardiac surgery. Methods: A total of 2750 patients admitted to our ICU after cardiac surgery from January 2003 to December 2009 are the basis for this observational study. Patients who developed ICU-acquired pneumonia were matched with patients without it in a 1:2 ratio. The matching criteria were age, urgent or scheduled surgery, surgical procedure, and the propensity score for pneumonia. Multiple regression analysis was used to find predictors of hospital mortality. The relationship between pneumonia and long-term survival was analyzed with Kaplan-Meier survival estimates and a risk-adjusted Cox proportional regression model for patients discharged alive from hospital. Results: Pneumonia was diagnosed in 32 (1.2%) patients and there were 19 cases per 1000 days of mechanical ventilation. Patients with pneumonia had a significantly higher hospital mortality rate (28% vs 6.2%, P ¼ .003) and a higher mortality at the end of follow-up (53% vs 19%, P < .0001) than those without it. Regression analysis showed that pneumonia was a strong predictor of hospital mortality. Five-year survival was as follows: pneumonia, 62%; control, 81%; and cohort patients, 91%. The Cox model showed that, after adjusting for confounding factors, patients with pneumonia (hazard ratio ¼ 3.96, 95% confidence interval [CI]: 1.41-11.14) had poorer long-term survival. Conclusion: Pneumonia remains a serious complication in patients operated for cardiac surgery and is associated with increased hospital mortality and reduced long-term survival. Keywords lung infection, outcomes, postoperative care, statistic propensity matching, surgery complications
Pneumonia develops in 1.2% to 9.7% of patients who undergo major cardiac surgery and is associated with severe outcomes during hospital stay1-5 and increased health care costs.6 However, knowledge about the effects of hospital-acquired pneumonia (HAP) on the outcome of cardiac surgery patients after hospital discharge is scant. Few available studies7-9 reporting the long-term outcome of intensive care unit (ICU) patients who develop ventilator-associated pneumonia (VAP) show a high mortality rate, prolonged period of mechanical ventilation and hospitalization, and increased medical costs. Interpretation of the results of studies is limited by the heterogeneous cohorts of patients included and because patients with VAP frequently have underlying disease that leads to poor long-term outcome of death even if VAP did not occur. Several studies on the effects of community-acquired pneumonia (CAP) after hospital discharge have clearly demonstrated that it is also associated with long-term mortality.10,11 The claim that comorbid conditions preceding pneumonia explain such increased long-term mortality is contentious.12
However, it has been stated that severe cardiac complications that develop after discharge are responsible for such bad outcomes in patients with CAP.13 The purpose of this study was to determine the effects of ICU-acquired pneumonia on hospital and long-term mortality in adult patients undergoing cardiac surgery.
1 Intensive Care Unit, Son Espases University Hospital, Palma de Mallorca, Balearic Islands, Spain 2 Cardiac Surgery Department, Son Espases University Hospital, Palma de Mallorca, Balearic Islands, Spain
Received July 28, 2013, and in revised form November 13, 2013. Accepted for publication December 9, 2013. Corresponding Author: Maria Riera, Intensive Care Unit, Son Espases University Hospital, Carretera de Valldemossa 79, 07120 Palma de Mallorca, Balearic Islands, Spain. Email: [email protected]
Downloaded from jic.sagepub.com at Bobst Library, New York University on November 16, 2015
2
Journal of Intensive Care Medicine
Materials and Methods Patients
Microbiology
Between January 2003 and December 2009, all patients who underwent major cardiac surgery in our hospital and were admitted to the cardiac surgery ICU were prospectively enrolled in a clinical registry. Our hospital is a 900-bed general hospital serving as a cardiac surgery referral center for a population of 1 000 000 inhabitants. The local institutional review board approved the study and waived the requirement for informed consent. We studied adult patients (age > 17 years) operated under extracorporeal circulation (ECC) or surgical revascularization without ECC and who stayed in the ICU at least for 48 hours. Cardiac transplantation is not performed in our hospital. Exclusion criteria were the presence of pneumonia or tracheobronchitis up to 15 days before cardiac surgery. The population and data collection methods have been previously described in detail.14 Briefly, clinical preoperative morbidities, operative, and postoperative data were prospectively recorded according to a preestablished protocol by a cardiac surgeon and an intensivist. The surgical risk was evaluated by the logistic European System for cardiac operative risk evaluation (EuroSCORE). Preoperative anemia was defined as hemoglobin
Long-Term Mortality After Pneumonia in Cardiac Surgery Patients: A PropensityMatched Analysis
Journal of Intensive Care Medicine 1-7 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/0885066614523918 jic.sagepub.com
J. Iban˜ez, MD, PhD1, M. Riera, MD, PhD1, R. Amezaga, MD1, J. Herrero, MD1, A. Colomar, MD1, C. Campillo-Artero, MD, PhD1, J. I. Saez de Ibarra, MD2, and O. Bonnin, MD2
Abstract Background: The role that intensive care unit (ICU)-acquired pneumonia plays in the long-term outcomes of cardiac surgery patients is not well known. This study examined the association of pneumonia with in-hospital mortality and long-term mortality after adult cardiac surgery. Methods: A total of 2750 patients admitted to our ICU after cardiac surgery from January 2003 to December 2009 are the basis for this observational study. Patients who developed ICU-acquired pneumonia were matched with patients without it in a 1:2 ratio. The matching criteria were age, urgent or scheduled surgery, surgical procedure, and the propensity score for pneumonia. Multiple regression analysis was used to find predictors of hospital mortality. The relationship between pneumonia and long-term survival was analyzed with Kaplan-Meier survival estimates and a risk-adjusted Cox proportional regression model for patients discharged alive from hospital. Results: Pneumonia was diagnosed in 32 (1.2%) patients and there were 19 cases per 1000 days of mechanical ventilation. Patients with pneumonia had a significantly higher hospital mortality rate (28% vs 6.2%, P ¼ .003) and a higher mortality at the end of follow-up (53% vs 19%, P < .0001) than those without it. Regression analysis showed that pneumonia was a strong predictor of hospital mortality. Five-year survival was as follows: pneumonia, 62%; control, 81%; and cohort patients, 91%. The Cox model showed that, after adjusting for confounding factors, patients with pneumonia (hazard ratio ¼ 3.96, 95% confidence interval [CI]: 1.41-11.14) had poorer long-term survival. Conclusion: Pneumonia remains a serious complication in patients operated for cardiac surgery and is associated with increased hospital mortality and reduced long-term survival. Keywords lung infection, outcomes, postoperative care, statistic propensity matching, surgery complications
Pneumonia develops in 1.2% to 9.7% of patients who undergo major cardiac surgery and is associated with severe outcomes during hospital stay1-5 and increased health care costs.6 However, knowledge about the effects of hospital-acquired pneumonia (HAP) on the outcome of cardiac surgery patients after hospital discharge is scant. Few available studies7-9 reporting the long-term outcome of intensive care unit (ICU) patients who develop ventilator-associated pneumonia (VAP) show a high mortality rate, prolonged period of mechanical ventilation and hospitalization, and increased medical costs. Interpretation of the results of studies is limited by the heterogeneous cohorts of patients included and because patients with VAP frequently have underlying disease that leads to poor long-term outcome of death even if VAP did not occur. Several studies on the effects of community-acquired pneumonia (CAP) after hospital discharge have clearly demonstrated that it is also associated with long-term mortality.10,11 The claim that comorbid conditions preceding pneumonia explain such increased long-term mortality is contentious.12
However, it has been stated that severe cardiac complications that develop after discharge are responsible for such bad outcomes in patients with CAP.13 The purpose of this study was to determine the effects of ICU-acquired pneumonia on hospital and long-term mortality in adult patients undergoing cardiac surgery.
1 Intensive Care Unit, Son Espases University Hospital, Palma de Mallorca, Balearic Islands, Spain 2 Cardiac Surgery Department, Son Espases University Hospital, Palma de Mallorca, Balearic Islands, Spain
Received July 28, 2013, and in revised form November 13, 2013. Accepted for publication December 9, 2013. Corresponding Author: Maria Riera, Intensive Care Unit, Son Espases University Hospital, Carretera de Valldemossa 79, 07120 Palma de Mallorca, Balearic Islands, Spain. Email: [email protected]
Downloaded from jic.sagepub.com at Bobst Library, New York University on November 16, 2015
2
Journal of Intensive Care Medicine
Materials and Methods Patients
Microbiology
Between January 2003 and December 2009, all patients who underwent major cardiac surgery in our hospital and were admitted to the cardiac surgery ICU were prospectively enrolled in a clinical registry. Our hospital is a 900-bed general hospital serving as a cardiac surgery referral center for a population of 1 000 000 inhabitants. The local institutional review board approved the study and waived the requirement for informed consent. We studied adult patients (age > 17 years) operated under extracorporeal circulation (ECC) or surgical revascularization without ECC and who stayed in the ICU at least for 48 hours. Cardiac transplantation is not performed in our hospital. Exclusion criteria were the presence of pneumonia or tracheobronchitis up to 15 days before cardiac surgery. The population and data collection methods have been previously described in detail.14 Briefly, clinical preoperative morbidities, operative, and postoperative data were prospectively recorded according to a preestablished protocol by a cardiac surgeon and an intensivist. The surgical risk was evaluated by the logistic European System for cardiac operative risk evaluation (EuroSCORE). Preoperative anemia was defined as hemoglobin
