Clinical and economic impact of diabetes following coronary artery bypass

Effects of hospital-acquired conditions on length of stay for patients with diabetes

BACKGROUND

Inpatients with diabetes have longer length of stays (LOS). Understanding patterns of in-hospital complications between patients with diabetes and others may reveal measures to improve patient welfare and minimise LOS.

AIM

This study evaluates the rates and types of hospital-acquired conditions among patients with and without diabetes and assesses any effects on LOS.

METHODS

A total of 47 615 admission episodes from The Northern Hospital over 12 months was reviewed. Episodes were divided into four groups: (i) patients without diabetes; (ii) patients with diabetes without end-organ sequelae (EOS); (iii) patients with diabetes with EOS; and (iv) a subset of non-diabetic patients with a Charlson Co-morbidity score ≥1 (comparison group). The Classification of Hospital Acquired Diagnoses (CHADx) was applied to the groups to compare rates and types of inpatient complications. Linear regression was used to analyse the impact of the number of CHADx on LOS.

RESULTS

Almost 30% of admissions of patients with diabetes and EOS had at least one CHADx, compared with 13% for non-diabetes patients and 17% for the comparison group. The types of CHADx experienced by diabetes patients with EOS were similar to the comparison group. However, rates were 10 times higher. Linear regression demonstrated diabetes patients with EOS have increased LOS and each CHADx per episode has a larger effect on LOS.

CONCLUSION

We demonstrate that diabetes patients have consistently higher rates of CHADx and longer LOS than similar patients with complex and chronic conditions. This provides a foundation for future studies to investigate preventative practices for this high-risk patient population.

Coronary artery bypass grafting in diabetics: A growing health care cost crisis

OBJECTIVES

To determine 4-decade temporal trends in the prevalence of diabetes and cardiovascular risk factors among patients undergoing coronary artery bypass grafting (CABG) and to compare in-hospital outcomes, resource utilization, and long-term survival after CABG in diabetics versus nondiabetics.

METHODS

From January 1972 to January 2011, 10,362 pharmacologically treated diabetics and 45,139 nondiabetics underwent first-time CABG. Median follow-up was 12 years. Direct technical cost data were available from 2003 onward (n = 4679). Propensity matching by diabetes status was used for outcome comparisons. Endpoints were in-hospital adverse events, resource utilization, and long-term survival.

RESULTS

Diabetics undergoing CABG increased from 7% in the 1970s to 37% in the 2000s. Their outcomes were worse, with more (P < .05) in-hospital deaths (2.0% vs 1.3%), deep sternal wound infections (2.3% vs 1.2%), strokes (2.2% vs 1.4%), renal failure (4.0% vs 1.3%), and prolonged postoperative hospital stay (9.6% vs 6.0%); and their hospital costs were 9% greater (95% confidence interval 7%-11%). Survival after CABG among diabetics versus nondiabetics at 1, 5, 10, and 20 years was also worse: 94% versus 94%, 80% versus 84%, 56% versus 66%, and 20% versus 32%, respectively. Propensity-matched patients incurred similar costs, but the prevalence of postoperative deep sternal wound infections and stroke, as well as long-term survival, remained worse in diabetics.

CONCLUSIONS

Diabetes is both a marker for high-risk, resource-intensive, and expensive care after CABG and an independent risk factor for reduced long-term survival. These issues, coupled with the increasing proportion of patients needing CABG who have diabetes, are a growing challenge in reining in health care costs.

Similar outcome in insulin-dependent and noninsulin-dependent diabetic patients after off-pump coronary artery bypass grafting with multiple skeletonized arterial conduits

BACKGROUND

We were interested in whether current multiarterial off-pump coronary artery bypass graft surgery can improve the clinical outcome for insulin-dependent diabetes mellitus patients.

METHODS

Between January 2002 and December 2013, 1,064 consecutive patients underwent isolated off-pump coronary artery bypass surgery at our hospital; 551 of these patients had diabetes. Of these 551 patients, 166 had insulin-dependent diabetes (IDM) and the remaining 385 had noninsulin-dependent diabetes (NIDM). The propensity score was calculated to achieve one-to-two matching sets (IDM 143 versus NIDM 286).

RESULTS

Ten patients (3.5%) in the NIDM group and 2 patients (1.4%) in the IDM group died in hospital (p = 0.18). Insulin dependency was not an independent risk factor for any early death or major complications. Follow-up was complete for 96.5% of the patients, with a mean follow-up of 4.6 ± 3.8 years. Overall survival rate at 10 years was 76.3% for the NIDM group and 73.1% for the IDM group (p = 0.79). The rate of 10-year actuarial freedom from major adverse cardiac events was 89.6% in the NIDM group and 86.3% in the IDM group (p = 0.72). Multivariate Cox proportional hazard regression analysis revealed that female sex, congestive heart failure, previous myocardial infarction, lower ejection fraction, and at least one major complication were independent risk factors for combined cardiac events. Insulin dependency did not affect any outcome in the long term.

CONCLUSIONS

Early and long-term outcomes after off-pump skeletonized multiarterial coronary artery bypass graft surgery were similar among the IDM and NIDM patients.

How important is glycemic control during coronary artery bypass?

In summary, poor perioperative glycemic control in patients undergoing CABG is associated with increased morbidity and mortality. Maintaining serum glucose less than or equal to 180 mg/dL in patients with diabetes during CABG reduces morbidity and mortality, lowers the incidence of wound infections, reduces hospital length of stay, and enhances long-term survival. In nondiabetic patients undergoing CABG surgery, maintaining serum glucose less than 180 mg/dL has also resulted in improved perioperative outcomes. More aggressive glycemic control (80-120 mg/dL) provides no added improvement in CABG patients with less than or equal to 3 days of ICU care in the absence of ventilatory support or multiorgan failure. Although the precise value for achieving glycemic control in the perioperative period is the subject of much debate, the benefits of perioperative glycemic control with continuous insulin infusions in patients undergoing CABG is no longer debatable.

Mortality in diabetic patients undergoing non-cardiac surgery: a 7-year follow-up study

BACKGROUND

The prognosis of diabetic patients after non-cardiac surgery remains controversial. This study was designed to compare the long-term mortality between diabetic and non-diabetic control patients undergoing non-cardiac surgery and to evaluate the possible risk factors.

METHODS

We investigated 274 consecutive diabetic patients and 282 non-diabetic control patients who underwent non-cardiac surgery within 1 year in a tertiary care hospital in Finland. The control group was matched for the same type of operations. Patients were followed for up to 7 years on average. The main outcome measure was mortality within 7 years.

RESULTS

Mortality both in the short-term postoperatively (< or =21 days) and in the long-term (up to 87 (1/2) months) was significantly higher in the diabetic patients compared with the non-diabetic group: 3.5 vs. 0% (P<0.05) and 37.2 vs. 15% (P<0.00001), respectively. The major causes of death among diabetic subjects were diseases of the cardiovascular system (56.8%) compared with non-diabetic patients (18.6%), P<0.0001. We found that diabetes mellitus per se is not a risk factor for post-operative mortality but a combination of variables had a significant effect on both short- and long-term mortality.

CONCLUSION

Diabetic patients undergoing non-cardiac surgery had a significantly higher incidence of short-term post-operative and long-term mortality compared with non-diabetic subjects. We propose a model of predictors of death among diabetic individuals undergoing non-cardiac surgery within a 7-year follow-up. The majority of deaths were associated with cardiovascular diseases.

The diabetic disadvantage: historical outcomes measures in diabetic patients undergoing cardiac surgery -- the pre-intravenous insulin era

Seven percent of the United States population is diabetic. However, diabetics are two to five times more likely to develop cardiovascular disease and therefore populate 30% of open heart procedures in this country. In addition, it has been well documented that diabetic cardiac surgery patients are further disadvantaged with worse outcomes following those procedures. This has been termed the "Diabetic Disadvantage." To benchmark these specific disadvantages, we evaluated the short- and long-term outcomes for diabetics and nondiabetics undergoing coronary artery bypass graft (CABG), CABG/valve, and aortic or mitral valve replacement surgery before the broader acceptance and use of intravenous insulin infusions in this patient population in 2001. All such patient records (n = 1,369,961) from the Society of Thoracic Surgeons national database operated on between 1990 and 2000 were assessed for short-term outcomes. Ten-year survival was evaluated among 36,835 patients from the Northern New England Cardiovascular Disease Study Group longitudinal registry. The diabetic population was found to have higher rates of 30-day mortality, deep sternal wound infection, stroke, and longer length of stay than the nondiabetic population. In addition, diabetic patients had approximately two-fold worse 10-year survival. All differences were statistically significant (P < 0.001). In summary, The Diabetic Disadvantage in the pre-intravenous insulin era is characterized by worse short- and long-term outcomes for diabetic patients undergoing cardiac surgery in the United States and Canada.

Cost analysis of aprotinin for coronary artery bypass patients: analysis of the randomized trials

BACKGROUND

The full kallikrein-inhibiting dose of aprotinin has been shown to reduce blood loss, transfusion requirements, and the systemic inflammatory response associated with cardiopulmonary bypass graft surgery (CABG). A half-dose regimen, although having a reduced delivery cost, inhibits plasmin and fibrinolysis without substantially effecting kallikrein-mediated inflammation associated with bypass surgery. The differing pharmacologic effects of the two regimens impact the decision-making process. The current study assessed the medical cost offset of full-dose and half-dose aprotinin from short- and long-term perspectives to provide a rational decision-making framework for clinicians.

METHODS

To estimate CABG admission costs, resource utilization and clinical data from aprotinin clinical trials were combined with unit costs estimated from a Duke University-based cost model. Lifetime medical costs of stroke and acute myocardial infarction were based on previous research.

RESULTS

Relative to placebo, the differences in total perioperative cost for primary CABG patients receiving full-dose or half-dose aprotinin were not significant. When lifetime medical costs of complications were considered, total costs in full-dose and half-dose aprotinin-treated patients were not different relative to that of placebo. Total perioperative cost was significantly lower for repeat CABG patients treated with aprotinin, with savings of $2,058 for full-dose and $2,122 for half-dose patients when compared with placebo. Taking lifetime costs of stroke and acute myocardial infarction into consideration, the cost savings estimates were $6,044 for full-dose patients and $4,483 for half-dose patients, due to substantially higher lifetime stroke costs incurred by the placebo patients.

CONCLUSIONS

Using this cost model, use of full-dose and half-dose aprotinin in primary CABG patients was cost neutral during hospital admission, whereas both dosing regimens were significantly cost saving in reoperative CABG patients. Additional lifetime cost savings were realized relative to placebo due to reduced complication costs, particularly with the full-dose regimen. As the full kallikrein-inhibiting dose of aprotinin has been shown to be safe and effective, the current results support its use in both primary and repeat CABG surgery. No demonstrable economic advantage was observed with the half-dose aprotinin regimen.

Coronary Artery Bypass Surgery in Diabetic Patients

BACKGROUND

Cardiovascular disease is a major cause of morbidity and mortality in patients with diabetes. This study examines the impact of diabetes on mortality and morbidity following coronary artery bypass surgery.

METHODS

We retrospectively analyzed 590 consecutive patients after coronary artery bypass grafting in 1998. Reoperations and combined procedures were excluded. A total of 137 diabetic (23.2%) and 453 nondiabetic patients were evaluated. Among the diabetics, 53 were treated with insulin and 84 were non-insulin-dependent. Diabetics suffered more frequently from hypertension, peripheral vascular disease, and more often had an increased body mass index (BMI).

RESULTS

There was no significant difference in mortality and major complications among insulin-dependent diabetics, non-insulin-dependent diabetics, and nondiabetic patients. Diabetics suffered more often from superficial sternal wound infection and had a higher incidence of superficial wound infections at the vein harvest site.

CONCLUSION

The present study suggests that diabetes increases the risk of superficial wound infections after coronary artery bypass grafting. But diabetics do not necessarily have an increased risk of major complications and mortality.

Coronary artery bypass grafting in type II diabetic patients: a comparison between insulin-dependent and non-insulin-dependent patients at short- and mid-term follow-up

BACKGROUND

Diabetes is a well-established risk factor for coronary artery disease, and it is associated with an increased rate of early and late adverse events after myocardial revascularization by coronary artery bypass grafting.

METHODS

A prospective follow-up study was done to evaluate the short-term and mid-term outcomes of type II diabetic patients who had coronary artery bypass grafting at our institution between 1996 and May 1999. A total of 200 patients, 100 insulin-dependent diabetic patients (group I) and 100 non-insulin-dependent diabetic patients (group II), met the inclusion criteria of the study and were included in the clinical follow-up study.

RESULTS

The characteristics of the patients of the two groups were similar for baseline clinical angiographic and operative characteristics. In particular, no significant differences in cardiopulmonary bypass and aortic cross-clamping times were noted between the two groups. The number grafts per patient was similar between the two groups. There were no in-hospital deaths, but postoperative complications were different among the two series. In fact, 33% of patients in group I had at least one major complication compared with 20% in group II (p = 0.037). The cumulative number of complications was 148 in group I and 69 in group II, and the mean number of complications per patient was 4.5 and 3.5 in groups I and II, respectively. The major differences in perioperative complication rates were found in the need for prolonged (> 24 hours) ventilation, occurrence of respiratory or renal insufficiency, and mediastinitis. The mean length of stay in the intensive care unit and for total hospitalization were longer in group I than group II (4.3 +/- 2.8 days versus 2.8 +/- 2.7 days [p = 0.010] and 11.1 +/- 2.2 days versus 7.2 +/- 2.4 group II [p < 0.05], respectively). At long-term follow-up, group I patients had a significantly higher mortality rate (29% versus 10%, p < 0.001). Moreover, overall late cardiac and noncardiac complication rates were significantly higher in group I than II (37% versus 22%, p = 0.02). In the multivariate analysis including several preoperative and operative variables, treatment by insulin, advanced age (> 75 years), left ventricular dysfunction (left ventricular ejection fraction < 35%), and complex lesions at coronary angiography (American Heart Association lesion classification type C lesion) were found as independent predictors of increased mortality.

CONCLUSIONS

Our data show that patients with insulin-dependent type II diabetes who had coronary artery bypass grafting have a significantly higher rate of major postoperative complications with an extremely unfavorable short- and long-term prognosis. Diabetic patients on insulin treatment should be considered high-risk candidates for coronary artery bypass grafting and require intense perioperative and long-term monitoring. Further studies will be necessary to investigate whether such conclusions may be appropriate for newer surgical strategies such as off-pump operation.

Increased hospital expenditures in diabetic patients hospitalized for cardiovascular diseases

OBJECTIVES

To measure the impact of diabetes on hospital resource use and expenditures in patients hospitalized for cardiovascular diseases (CVD).

RESEARCH DESIGN AND METHODS

We conducted an observational study of 4865 hospitalizations for CVD over 2 years (January 1998 to December 1999). Information with respect of the presence of diabetes mellitus, length of stay, readmissions, mortality, and costs were obtained through retrospective chart review.

RESULTS

Diabetic patients accounted for 35.1% of hospital admissions (1706 admissions), 40.8% of hospital stays (23,309 days), and 39% of direct medical cost (5,735,884 euros). On average, diabetic patients had longer hospital stay (13.6+/-13.2 vs. 10.7+/-11.2 days; P<.001) and direct in-patient cost (3438+/-4308 vs. 2513+/-3384 euros; P<.001) and experienced more readmissions (relative risk: 1.67; 95% CI: 1.45-1.91) compared with nondiabetic patients. However, despite the hospital mortality rate being higher in nondiabetic patients (6.3% vs. 5.8%), these results were not statistically significant (relative risk: 1.09; 95% CI: 0.86-1.40).

CONCLUSIONS

Diabetic patients hospitalized for CVD have longer hospital stay, greater risk of short-term readmission, and are more costly than nondiabetic patients. However, in-hospital mortality risk in patients hospitalized by CVD is no greater in diabetic than in nondiabetics.

Percutaneous coronary intervention versus coronary bypass graft surgery for diabetic patients with unstable angina and risk factors for adverse outcomes with bypass: outcome of diabetic patients in the AWESOME randomized trial and registry

OBJECTIVES

This study compared survival after percutaneous coronary intervention (PCI) with survival after coronary artery bypass graft surgery (CABG) among diabetics in the Veterans Affairs AWESOME (Angina With Extremely Serious Operative Mortality Evaluation) study randomized trial and registry of high-risk patients.

BACKGROUND

Previous studies indicate that CABG may be superior to PCI for diabetics, but no comparisons have been made for diabetics at high risk for surgery.

METHODS

Over five years (1995 to 2000), 2,431 patients with medically refractory myocardial ischemia and at least one of five risk factors (prior CABG, myocardial infarction within seven days, left ventricular ejection fraction <0.35, age >70 years, or an intra-aortic balloon being required to stabilize) were identified. A total of 781 were acceptable for CABG and PCI, and 454 consented to be randomized. The 1,650 patients not acceptable for both CABG and PCI constitute the physician-directed registry, and the 327 who were acceptable but refused to be randomized constitute the patient-choice registry. Diabetes prevalence was 32% (144) among randomized patients, 27% (89) in the patient-choice registry, and 32% (525) in the physician-directed registry. The CABG and PCI survival rates were compared using Kaplan-Meier curves and log-rank tests.

RESULTS

The respective CABG and PCI 36-month survival rates for diabetic patients were 72% and 81% for randomized patients, 85% and 89% for patient-choice registry patients, and 73% and 71% for the physician-directed registry patients. None of the differences was statistically significant.

CONCLUSIONS

We conclude that PCI is a relatively safe alternative to CABG for diabetic patients with medically refractory unstable angina who are at high risk for CABG.

Diabetes mellitus increases short-term mortality and morbidity in patients undergoing coronary artery bypass graft surgery

OBJECTIVES

The aim of this study was to determine the impact of diabetes mellitus (DM) on short-term mortality and morbidity in patients undergoing coronary artery bypass surgery (CABG).

BACKGROUND

Diabetes mellitus is present in approximately 20% to 30% of patients undergoing CABG, and the impact of diabetes on short-term outcome is unclear.

METHODS

We performed a retrospective cohort study in 434 hospitals from North America. The study population included 146,786 patients undergoing CABG during 1997: 41,663 patients with DM and 105,123 without DM. The primary outcome was 30-day mortality. Secondary outcomes were in-hospital morbidity, infections and composite outcomes of mortality or morbidity and mortality or infection.

RESULTS

The 30-day mortality was 3.7% in patients with DM and 2.7% in those without DM; the unadjusted odds ratio was 1.40 (95% confidence interval [CI], 1.31 to 1.49). After adjusting for other baseline risk factors, the overall adjusted odds ratio for diabetics was 1.23 (95% CI, 1.15 to 1.32). Patients treated with oral hypoglycemic medications had adjusted odds ratio 1.13; 95% CI, 1.04 to 1.23, whereas those on insulin had an adjusted odds ratio 1.39; 95% CI, 1.27 to 1.52. Morbidity, infections and the composite outcomes occurred more commonly in diabetic patients and were associated with an adjusted risk about 35% higher in diabetics than nondiabetics, particularly among insulin-treated diabetics (adjusted risk between 1.5 to 1.61).

CONCLUSIONS

Diabetes mellitus is an important risk factor for mortality and morbidity among those undergoing CABG. Research is needed to determine if good control of glucose levels during the perioperative time period improves outcome.

Nonrandom selection and the attributable cost of surgical-site infections

OBJECTIVE

To study the extent to which selection bias poses problems for estimating the attributable cost of deep chest surgical-site infection (SSI) following coronary artery bypass graft (CABG) surgery.

DESIGN

Reanalysis of a prospective case-control study.

SETTING

A large, Midwestern community medical center.

PATIENTS

Cases were all patients who had an SSI (N = 41) following CABG and CABG and valve surgery between April 1996 and March 1998. Controls were every tenth uninfected patient (N = 160).

METHODS

Estimates of the attributable cost of deep chest SSI were computed using unmatched comparison, matched comparison, linear regression, and Heckman's two-stage approach.

RESULTS

The attributable cost of deep chest SSI was estimated to be $20,012 by unmatched comparison, $19,579 by matched comparison, $20,103 by linear regression, and $14,211 by Heckman's two-stage method. Controlling for selection bias substantially reduced the cost estimate, but the coefficient capturing selection bias was not statistically significant.

CONCLUSIONS

Deep chest SSI significantly increases the cost of care for patients who undergo CABG surgery. Unmatched comparison, matched comparison, and linear regression estimated the attributable cost to be approximately $20,000. Although controlling for selection bias with Heckman's two-stage method resulted in a substantially smaller estimate, the coefficient for selection bias was not statistically significant, suggesting that the estimates derived from the other models should be acceptable. However, the magnitude of the difference between the models shows that the effect of selection bias can be substantial. Some exploration for selection bias is recommended when estimating the attributable cost of SSIs.

Factors predicting prolonged length of stay after carotid endarterectomy

BACKGROUND

Over the last several years, implementation of critical pathways in patients undergoing carotid endarterectomy has decreased postoperative length of stay significantly. Discharge the day after surgery has become commonplace in many centers, including our own. Unfortunately, managed care may interpret this refinement as a standard of care and limit reimbursement or even disallow admissions extending beyond 1 day. We therefore examined our carotid registry to identify risk factors associated with postoperative length of stay exceeding 1 day.

METHODS

We retrospectively reviewed all patients undergoing carotid endarterectomy at our academic center from May 1996 through April 1999. Combined procedures and patients undergoing subsequent noncarotid-related procedures on those admissions were excluded. The charts were inspected for atherosclerosis risk factors, including sex and age, specific attending surgeon, side of the surgery, use of intravenous vasoactive drugs, actual preoperative blood pressure, and presence of neurologic symptoms or postoperative complications. Multiple regression analysis was performed on all collected variables. Statistical significance was inferred for P less than.05.

RESULTS

A total of 188 patients met the study criteria and had complete, retrievable medical records. A mean postoperative length of stay of 1.65 +/- 0.08 days and a mean total length of stay of 2.17 +/- 0.14 days were observed. Fifty-seven percent of patients went home the day after surgery. There was a 1.6% stroke-mortality rate. Significant predictors of a prolonged stay, listed in order of decreasing importance on the basis of their calculated contribution to prolonging the postoperative length of stay, are as follows (P value; beta coefficient): postoperative complications (<.0001; 1.03), age > 79 years (.008; 0.547), diabetes mellitus (.011; 0.407), female sex (.007; 0.398), and intravenous vasodilator requirement (. 035; 0.382). Other atherosclerosis risk factors, prior neurologic symptoms, the postoperative use of vasopressors, and reoperative surgery did not contribute to extended length of stay.

CONCLUSIONS

Discharge on the first postoperative day is feasible in many, but not all, patients undergoing carotid endarterectomy. Our data help define subsets of patients at risk for prolonged postoperative stay. Targeting these subsets for preoperative medical and social interventions may allow safe early discharge more frequently.