Interact CardioVasc Thorac Surg 2009;9:827-831. doi:10.1510/icvts.2009.210872
© 2009 European Association of Cardio-Thoracic Surgery
Institutional report - Cardiopulmonary bypass |
Age  75 years is associated with greater resource utilization following coronary artery bypass grafting
Iqbal Toora,
Ameet Bakhaib,
Bruce Keogha,
Miles Curtisa and
John Yapa,*
a The Heart Hospital, University College London Hospitals NHS Foundation Trust, 16–18 Westmoreland Street, London W1G 8PH, UK
b Barnet Hospital, Wellhouse Lane, Barnet, Herts EN5 3DJ, UK
Received 30 April 2009;
received in revised form 5 August 2009;
accepted 10 August 2009
*Corresponding author. Tel.: +44 20 7504 8942; fax: +44 20 7504 8943.
E-mail address: john.yap{at}uclh.nhs.uk (J. Yap).
 |
Abstract
|
|---|
We examined whether complication rates and resource utilization among elderly patients undergoing coronary artery bypass grafting (CABG) differed from their younger counterparts. A retrospective review of prospectively collected data was conducted of 2936 patients undergoing first-time isolated CABG. Demographic and baseline clinical characteristics were collected, and patients grouped according to age into those <75 years (n=2424, younger) and  75 years (n=512, older). Major postoperative complications were recorded and data collected on indicators of resource utilization, which included intensive care unit (ICU) length of stay (LOS), postoperative LOS and total hospital LOS. In comparison with younger patients, older patients were more likely to be female (26.6% vs. 18.1%, P<0.0001) and require an urgent procedure (46.4% vs. 33.3%, P<0.0001). Postoperative complications were significantly higher in elderly patients (43.7% vs. 23.0%; odds ratio (OR)=2.5, 95% confidence interval (CI) [2.0–3.1]; P<0.0001). Older patients incurred longer intensive care stays (2 days interquartile range (IQR) [1–3] vs. 1 day IQR [1–2]; P<0.0001) and a longer postoperative stay (8 days IQR [6–11] vs. 6 days IQR [5–8]; P<0.0001). Multivariate logistic regression analysis showed age 75 years was an independent predictor of postoperative LOS (OR=1.23, 95% CI [0.49–1.96]; P=0.001). Older patients aged 75 years undergoing CABG had significantly higher rates of postoperative complications and greater resource utilization than their younger counterparts.
Key Words: Coronary artery bypass grafting; Elderly; Length of stay
|
1. Introduction
|
|---|
The incidence of coronary artery disease (CAD) continues to increase with age and, as a result, so does the need for revascularization procedures in elderly patients [1]. Elderly patients referred for coronary artery bypass grafting (CABG) commonly have complex CAD and multiple co-morbidities. The rate of in-hospital mortality for elderly patients has continued to decline over the past decade as a result of advances in surgical, anaesthetic techniques and intensive care [2–4]. CABG is considered a safe and efficacious treatment for elderly patients with symptomatic CAD refractory to medical therapy. However, studies have shown that older patients are more likely to suffer postoperative complications with resulting longer postoperative length of stay (LOS) and higher hospital cost [5–8].
CABG is one of the most costly surgical procedures routinely performed. To the best of our knowledge, data on resource utilization and postoperative complications for patients undergoing CABG in the contemporary setting within the UK have not been reported. These data would be important in identifying areas for improvement of postoperative care and indicate the actual level of resources a hospital has to commit for the service provision of CABG. In the UK, a fixed tariff payment is received by National Health Service (NHS) hospitals under the ‘Payment by Result’ scheme [9], for each CABG performed, which is irrespective of a patient's age. We sought to examine whether complication rates and resource utilization among elderly patients undergoing CABG differed from their younger counterparts. This would help identify whether there should be a separate tariff payment for patient's 75 years undergoing CABG.
|
2. Methods
|
|---|
2.1. Study setting
This study was a retrospective, single-centre, cohort study including 2936 consecutive patients undergoing first-time isolated CABG at a tertiary cardiac unit in London, between 1 January 2002 and 31 December 2006. Patients who underwent associated procedures [valve repair or replacement, resection of a ventricular aneurysm with or without remodelling of the left ventricle (LV), or combined carotid artery surgery], ‘redo’ CABG, emergency CABG or off-pump CABG were excluded. For the purpose of this study, all patients aged 75 years were considered to be older and patients <75 years were considered to be younger.
2.2. Baseline characteristics
For each patient, demographic and clinical data were extracted from the CABG database, maintained by designated senior audit officers. Preoperative clinical factors including urgency of procedure (elective, urgent), coronary risk factors [diabetes mellitus, hypertension, hyperlipidaemia, smoking, myocardial infarction (MI), prior percutaneous coronary intervention (PCI)], co-morbidities [heart failure, cerebrovascular accident (CVA), renal failure, peripheral vascular disease (PVD)], coronary disease severity [extent of CAD, severity of left main stem (LMS) disease and LV function] were available. Predicted mortality for patients was determined using the European System for Cardiac Operative Risk Evaluation (EuroSCORE) [10].
2.3. Intra- and postoperative data
Data were collected on procedural details (cardiopulmonary bypass time, cross-clamp time, number of distal coronary grafts, type of conduit used for revascularisation) and postoperative complications [CVA (neurological deficit that persisted at discharge), post-bypass initiation of intra-aortic balloon pump (IABP), re-operation for excessive bleeding, wound infection, pneumonia, new onset renal failure requiring haemodialysis, and new onset atrial fibrillation (AF)]. For each patient, intensive care unit (ICU) LOS, postoperative LOS and total hospital LOS was determined. In-hospital mortality was defined as death during the same hospital admission as the operation, regardless of cause.
2.4. Statistical analysis
Categorical variables are expressed as percent (frequencies), and continuous variables with a non-normal distribution are presented as the median with interquartile range (IQR). Odds ratios (OR) are reported with 95% confidence intervals (CI). For categorical variables, differences between groups were assessed using the Pearson  2-test or two-tailed Fisher's exact test. Continuous variables with a normal distribution were analysed using Student t-test, and variables with a non-normal distribution were analysed using Wilcoxon rank test. Multivariate linear regression, using a stepwise approach including biologically plausible variables, was used to identify independent predictors of postoperative LOS. Variables were entered into the regression model based on univariate association (P<0.1) with the dependent variable. Statistical analysis was completed using SPSS 14.0 (SPSS Inc, Chicago, IL) for Windows. A P 0.05 was considered statistically significant.
|
3. Results
|
|---|
Over the study period, 512 (17.4%) CABG procedures were performed in patients' 75 years. Over time, there was a trend towards a higher proportion of patients 75 years being referred for CABG (2002: 15.2% (101); 2003: 16.5% (95); 2004: 16.1% (91); 2005: 19.6% (114); 2006: 20.1% (111), P=0.09). With an increasing proportion being elective (2002: 51.5% (52); 2003: 52.1% (50); 2004: 50.5% (46); 2005: 54.5% (61); 2006: 59.5% (66), P=0.24). The preoperative clinical characteristics of patients in the two age groups are summarized in Table 1. There was a significantly higher percentage of women in the older age group. Compared with the younger patients, older patients were more likely to undergo urgent CABG surgery (46.4% vs. 33.3%, P<0.0001), have a LMS stenosis 50% (31.1% vs. 22.7%, P<0.0001) and have a history of PVD (14.8% vs. 10.1%, P=0.002). Older patients were less likely to have asymptomatic heart failure NHYA class I (38.7% vs. 43.8%, P=0.04) and were less likely to have an ejection fraction 50% (62.5% vs. 70.8%, P=0.002).
Compared with younger patients, older patients undergoing CABG were less likely to receive left internal mammary artery (LIMA) grafts (81.4% vs. 92.4%, P<0.0001). However, over the study period there was an increase in the number of patient 75 years receiving LIMA grafts (2002: 64.4% (65); 2003: 70.5% (67); 2004: 84.6% (77); 2005: 92.1% (105); 2006: 92.8% (103), P<0.0001). Both age groups had a similar number of vessels bypassed and the total cross-clamp times were comparable (37 min IQR (30–47) vs. 37 min IQR (30–48), P=0.29). There also was no statistically significant difference in the requirement for IABP support following surgery (Table 2).
Postoperative complications are shown in Table 3. The incidence of CVA, new onset AF and new onset renal failure requiring haemodialysis was significantly higher in patients 75 years. Patients 75 years were more likely to return to the operating room (any cause) and in particular for the exploration of postoperative bleeding. The most common postoperative complication in both age groups was new onset of AF. Overall, the rate of postoperative complications was substantially higher in elderly patients compared to their younger counterparts (43.7% vs. 23.0%; OR=2.5, 95% CI [2.0–3.1]; P<0.0001) (Table 3).
The in-hospital mortality rate for the study population was 1.5% (45). Over the study period, there was a significant decrease in risk of in-hospital mortality during each consecutive year (OR=[–0.004], 95% CI ([–0.007]–[–0.001]); P=0.01), whilst the complexity of patients as measured by the EuroSCORE actually significantly increased annually (OR=0.078, 95% CI (0.018–0.14), P=0.01). When patients were separated by urgency of procedure the risk of in-hospital mortality for urgent procedures remained higher in the older age group (7.1% (17) vs. 1.1% (9), P<0.0001), but the difference between the age groups was reduced in those undergoing elective CABG (2.2% (6) vs. 0.8% (13), P=0.04). Independent predictor of in-hospital mortality included the year of surgery, age, history of hypertension, myocardial infraction, PVD, renal impairment, prior PCI, postoperative complications, and IABP following surgery (Table 4).
Postoperative LOS (8 days IQR [6–11] vs. 6 days IQR [5–8], P<0.0001) and total hospital LOS (10 days IQR [8–15] vs. 8 days IQR [7–11], P<0.0001) were significantly longer for older patients (Table 5). The total hospital LOS for elderly patients experiencing one or more postoperative complications (excluding mortality) following CABG was substantially longer than that of patients <75 years (12 days IQR [9–18] vs. 8 days IQR [7–11], P<0.0001). After controlling for baseline clinical characteristics, intraoperative variables and postoperative complications, age 75 years (OR=1.23, 95% CI (0.49–1.96), P=0.001) was an independent predictor of postoperative LOS (Table 6).
|
4. Discussion
|
|---|
Our study examined clinical outcome, complication rates and resource utilization for patients <75 and 75 years old, over a 5-year study period in a UK cardiothoracic centre. We found that patients 75 years old had a higher rate of postoperative complications, longer postoperative LOS and higher mortality rates. Patients 75 years old were 15 years older than their younger counterparts and were more likely to be referred for urgent CABG and have a greater number of co-morbidities.
In-hospital mortality rates for both age groups were similar to those reported in previous studies [3, 11]. Age was confirmed as an independent predictor of in-hospital mortality. However, hypertension which does not feature in the EuroSCORE calculation was also an independent predictor of in-hospital mortality [10]. Separating patients by urgency of CABG showed that the risk of in-hospital mortality for urgent procedures remained higher in the older age group, but the difference between the age groups was markedly reduced in those undergoing elective CABG.
The median postoperative LOS for patients 75 years was two days longer than their younger counterparts. After controlling for baseline clinical characteristics and postoperative complications, we found age 75 years to be an independent predictor of postoperative LOS. Previous studies have also shown older patients to have a longer postoperative and total hospital LOS [3, 11]. Over the past decade, postoperative LOS has been reported as being on average 2–3 days longer in older patients undergoing CABG [2, 11, 12]. Several studies have shown that age is an independent predictor of delayed extubation following CABG and consequently older patients have longer ICU LOS [2, 3, 13]. We also found that patients 75 years old were ventilated for longer periods and spent significantly longer time on the ICU. A number of other factors may contribute towards older patients having a longer postoperative recovery period. Elderly patients had more than a two-fold increase in postoperative complication rate compared with their younger counterparts.
Over the past decade, there have been changes in the clinical characteristics of patients undergoing CABG. It is now more common for older patients with multiple co-morbidities to be considered for CABG. This will need to be matched by an increased input of resources for the delivery of postoperative care, in order to meet the needs of the increasing complexity of patients undergoing CABG.
Our study has several key limitations as it is a single centre study and several surgeons have participated for differing periods. Given that we are a tertiary referral centre we often repatriate patients for further convalescence to their local hospitals. Older patients are more likely to be repatriated, however, despite this they had a longer duration of stay with us, making our estimates conservative regarding their increased total resource use.
|
5. Conclusion
|
|---|
Age 75 years was an independent predictor of postoperative LOS following CABG. Postoperative complications are both significantly higher in older patients than their younger counterparts and associated with a substantially longer postoperative LOS. In order to provide adequate funding for cardiothoracic centres, which are now increasingly performing CABG for elderly patients, there is a case for a separate tariff payment for patients 75 years.
|
References
|
|---|
- Menotti A, Lanti M, Puddu PE, Kromhout D. Coronary heart disease incidence in northern and southern European populations: a reanalysis of the seven countries study for a European coronary risk chart. Heart 2000;84:238–244.[Abstract/Free Full Text]
- Scott BH, Seifert FC, Grimson R, Glass PS. Octogenarians undergoing coronary artery bypass graft surgery: resource utilization, postoperative mortality, and morbidity. J Cardiothorac Vasc Anesth 2005;19:583–588.[CrossRef][Medline]
- Hirose H, Amano A, Yoshida S, Takahashi A, Nagano N, Kohmoto T. Coronary artery bypass grafting in the elderly. Chest 2000;117:1262–1270.[Abstract/Free Full Text]
- Baskett R, Buth K, Ghali W, Norris C, Maas T, Maitland A, Ross D, Forgie R, Hirsch G. Outcomes in octogenarians undergoing coronary artery bypass grafting. Can Med Assoc J 2005;172:1183–1186.[Abstract/Free Full Text]
- Avery GJ 2nd, Ley SJ, Hill JD, Hershon JJ, Dick SE. Cardiac surgery in the octogenarian: evaluation of risk, cost, and outcome. Ann Thorac Surg 2001;71:591–596.[Abstract/Free Full Text]
- Rady MY, Ryan T, Starr NJ. Perioperative determinants of morbidity and mortality in elderly patients undergoing cardiac surgery. Crit Care Med 1998;26:225–235.[CrossRef][Medline]
- Piccione W Jr. Cardiac surgery in the elderly: what have we learned. Crit Care Med 1998;26:196–197.[CrossRef][Medline]
- Keogh B, Kinsman R. Fifth National Adult Cardiac Surgical Database Report 2003: improving outcomes for patients. Reading: Dendrite Clinical Systems; 2004.
- Department of Health. Reforming NHS financial flows: introducing payment by results. London: Department of Health; 2002.
- Nashef SA, Roques F, Michel P, Gauducheau E, Lemeshow S, Salamon R. European system for cardiac operative risk evaluation (EuroSCORE). Eur J Cardiothorac Surg 1999;16:9–13.[Abstract/Free Full Text]
- Chee JH, Filion KB, Haider S, Pilote L, Eisenberg MJ. Impact of age on hospital course and cost of coronary artery bypass grafting. Am J Cardiol 2004;93:768–771.[CrossRef][Medline]
- Nallamothu BK, Saint S, Eagle KA, Langa KM, Fendrick AM, Hogikyan RV, Kelley K, Ramsey SD. Coronary artery bypass grafting in octogenarians: clinical and economic outcomes at community-based healthcare facilities. Am J Manag Care 2002;8:749–755.[Medline]
- Wong DT, Cheng DC, Kustra R, Tibshirani R, Karski J, Carroll-Munro J, Sandler A. Risk factors of delayed extubation, prolonged length of stay in the intensive care unit, and mortality in patients undergoing coronary artery bypass graft with fast-track cardiac anesthesia: a new cardiac risk score. Anesthesiology 1999;91:936–944.[CrossRef][Medline]
|
|
Top
Abstract
1. Introduction
