Charles Oprian

Outcomes 15 years after valve replacement with a mechanical versus a bioprosthetic valve : Final report of the Veterans Affairs randomized trial

OBJECTIVES The goal of this study was to compare long-term survival and valve-related complications between bioprosthetic and mechanical heart valves. BACKGROUND Different heart valves may have different patient outcomes. METHODS Five hundred seventy-five patients undergoing single aortic valve replacement (AVR) or mitral valve replacement (MVR) at 13 VA medical centers were randomized to receive a bioprosthetic or mechanical valve. RESULTS By survival analysis at 15 years, all-cause mortality after AVR was lower with the mechanical valve versus bioprosthesis (66% vs. 79%, p = 0.02) but not after MVR. Primary valve failure occurred mainly in patients <65 years of age (bioprosthesis vs. mechanical, 26% vs. 0%, p < 0.001 for AVR and 44% vs. 4%, p = 0.0001 for MVR), and in patients > or =65 years after AVR, primary valve failure in bioprosthesis versus mechanical valve was 9 +/- 6% versus 0%, p = 0.16. Reoperation was significantly higher for bioprosthetic AVR (p = 0.004). Bleeding occurred more frequently in patients with mechanical valve. There were no statistically significant differences for other complications, including thromboembolism and all valve-related complications between the two randomized groups. CONCLUSIONS At 15 years, patients undergoing AVR had a better survival with a mechanical valve than with a bioprosthetic valve, largely because primary valve failure was virtually absent with mechanical valve. Primary valve failure was greater with bioprosthesis, both for AVR and MVR, and occurred at a much higher rate in those aged <65 years; in those aged > or =65 years, primary valve failure after AVR was not significantly different between bioprosthesis and mechanical valve. Reoperation was more common for AVR with bioprosthesis. Thromboembolism rates were similar in the two valve prostheses, but bleeding was more common with a mechanical valve.

A Comparison of Outcomes in Men 11 Years after Heart-Valve Replacement with a Mechanical Valve or Bioprosthesis

BACKGROUND Mechanical heart valves are durable but thrombogenic, and their use requires that the patient receive anticoagulants. In contrast, bioprosthetic valves are less thrombogenic, but they have limited durability because of tissue deterioration. METHODS To compare the outcomes of patients who receive these two types of valves, we randomly assigned 575 men scheduled to undergo aortic-valve or mitral-valve replacement to receive either a mechanical or a bioprosthetic valve. The primary end points were death from any cause and any valve-related complication. RESULTS During an average follow-up of 11 years, there was no difference between the two groups in the probability of death from any cause (11-year probability for mechanical valves, 0.57; for bioprostheses, 0.62; P = 0.57) or in the probability of any valve-related complication (0.65 and 0.69, respectively; P = 0.39). There was a much higher rate of structural valve failure among patients who received bioprosthetic valves (11-year probability, 0.15 for the aortic valves and 0.36 for the mitral valves) than among those who received mechanical valves (no valve failures; P < 0.001). However, this difference was offset by a higher rate of bleeding complications among patients with mechanical valves than among those with bioprosthetic valves (11-year probability, 0.42 and 0.26, respectively; P < 0.001) and by a greater frequency of peri-prosthetic valvular regurgitation among patients with mechanical mitral valves than among those with mitral bioprostheses (11-year probability, 0.17 and 0.09, respectively; P = 0.05). CONCLUSIONS After 11 years, the rates of survival and freedom from all valve-related complications were similar for patients who received mechanical heart valves and those who received bioprosthetic heart valves. However, structural failure was observed only with the bioprosthetic valves, whereas bleeding complications were more frequent among patients who received mechanical valves.

Risk factors for morbidity and mortality after colectomy for colon cancer

PURPOSE: Comorbid conditions affect the risk of adverse outcomes after surgery, but the magnitude of risk has not previously been quantified using multivariate statistical methods and prospectively collected data. Identifying factors that predict results of surgical procedures would be valuable in assessing the quality of surgical care. This study was performed to define risk factors that predict adverse events after colectomy for cancer in Department of Veterans Affairs Medical Centers. METHODS: The National Veterans Affairs Surgical Quality Improvement Program contains prospectively collected and extensively validated data on more than 415,000 surgical operations. All patients undergoing colectomy for colon cancer from 1991 to 1995 who were registered in the National Veterans Affairs Surgical Quality Improvement Program database were selected for study. Independent variables examined included 68 preoperative and 12 intraoperative clinical risk factors; dependent variables were 21 specific adverse outcomes. Stepwise logistic regression analysis was used to construct models predicting the 30-day mortality rate and 30-day morbidity rates for each of the ten most frequent complications. RESULTS: A total of 5,853 patients were identified; 4,711 (80 percent) underwent resection and primary anastomosis. One or more complications were observed in 1,639 of 5,853 (28 percent) patients. Prolonged ileus (439/5,853; 7.5 percent), pneumonia (364/5,853; 6.2 percent), failure to wean from the ventilator (334/5,853; 5.7 percent), and urinary tract infection (292/5,853; 5 percent) were the most frequent complications. The 30-day mortality rate was 5.7 percent (335/5,853). For most complications, 30-day in-hospital mortality rates were significantly higher for patients with a complication than for those without. Thirty-day mortality rates exceeded 50 percent if postoperative coma, cardiac arrest, a pre-existing vascular graft prosthesis that failed after colectomy, renal failure, pulmonary embolism, or progressive renal insufficiency occurred. Preoperative factors that predicted a high risk of 30-day mortality included ascites, serum sodium >145 mg/dl, “do not resuscitate” status before surgery, American Society of Anesthesiologists classes III and IV OR V, and low serum albumin. CONCLUSIONS: Mortality rates after colectomy in Veterans Affairs hospitals are comparable with those reported in other large studies. Ascites, hypernatremia, do not resuscitate status before surgery, and American Society of Anesthesiologists classes III and IV OR V were strongly predictive of perioperative death. Clinical trials to decrease the complication rate after colectomy for colon cancer should focus on these risk factors.

Prognostic models of thirty-day mortality and morbidity after major pulmonary resection ☆ ☆☆ ★

BACKGROUND A part of the prospective, multi-institutional National Veterans Affairs Surgical Quality Improvement Program was developed to predict 30-day mortality and morbidity for patients undergoing a major pulmonary resection. METHODS Perioperative data were acquired from 194,319 noncardiac surgical operations at 123 Veterans Affairs Medical Centers between October 1, 1991, and August 31, 1995. Current Procedural Terminology code-based analysis was undertaken for major pulmonary resections (lobectomy and pneumonectomy). Preoperative, intraoperative, and outcome variables were collected. The 30-day mortality and morbidity models were developed by means of multivariable stepwise logistic regression with the preoperative and intraoperative variables used as independent predictors of outcome. RESULTS A total of 3516 patients (mean age 64 9 years) underwent either lobectomy (n = 2949) or pneumonectomy (n = 567). Thirty-day mortality was 4.0% for lobectomy (119/2949) and 11.5% for pneumonectomy (65/567). The preoperative predictors of 30-day mortality were albumin, do not resuscitate status, transfusion of more than 4 units, age, disseminated cancer, impaired sensorium, prothrombin time more than 12 seconds, type of operation, and dyspnea. When the intraoperative variables were considered, intraoperative blood loss was added to the preoperative model. In the presence of these intraoperative variables in the model, do not resuscitate status and prothrombin time more than 12 seconds were only marginally significant. Thirty-day morbidity, defined as the presence of 1 or more of the 21 predefined complications, was 23.8% for lobectomy (703/2949) and 25.7% for pneumonectomy (146/567). In multivariable models, independent preoperative predictors (P <.05) of 30-day morbidity were age, weight loss greater than 10% in the 6 months before surgery, history of chronic obstructive pulmonary disease, transfusion of more than 4 units, albumin, hemiplegia, smoking, and dyspnea. When intraoperative variables were added to the preoperative model, the duration of operation time and intraoperative transfusions were included in the model and albumin became marginally significant. CONCLUSIONS This analysis identifies independent patient risk factors that are associated with 30-day mortality and morbidity for patients undergoing a major pulmonary resection. This series provides an initial risk-adjustment model for major pulmonary resections. Future refinements will allow comparative assessment of surgical outcomes and quality of care at many institutions.

Risk Factors for Adverse Outcomes After the Surgical Treatment of Appendicitis in Adults

Objective To define risk factors that predict adverse outcomes after the surgical treatment of appendicitis in Department of Veterans Affairs Medical Centers. Summary Background Data Risk factors for adverse outcomes after the surgical treatment of appendicitis in adults are poorly defined. Accurate presurgical assessment of the risk of perioperative complications and death is important in planning surgical therapy. Methods The VA National Surgical Quality Improvement Program contains prospectively collected and extensively validated data on ∼1,000,000 major surgical operations. All patients undergoing surgical intervention for appendicitis from 1991 to 1999 registered in this database were selected for study. Independent variables examined included 68 putative preoperative risk factors and 12 intraoperative process measures. Dependent variables were 21 specific adverse outcomes, including death. Stepwise logistic regression analysis was used to construct models predicting 30-day morbidity rate and the 30-day postoperative mortality rate. Results There were 4163 patients identified. The mean age was 50 years; 96% were male. Sixteen percent of patients had 1 or more complications after surgical intervention. Prolonged ileus, failure to wean from the ventilator, pneumonia, and both superficial and deep wound infection were the most frequently reported complications, accounting for the majority of the morbidity. The 30-day mortality rate was 1.8% (74 deaths). For >50% of the complications reported, the 30-day mortality rates were significantly higher (P < 0.01) for patients with complications than for those without. Thirty-day mortality rates for several complications exceeded 30%, including cardiac arrest, coma >24 hours, myocardial infarction, acute renal failure, bleeding requiring >4 units of red cells, and systemic sepsis. Four preoperative factors predicted a high risk of 30-day mortality in the logistic regression analysis: “completely dependent” functional status, bleeding disorder, steroid usage, and current pneumonia. “Threat to life” or “moribund” American Society of Anesthesiologists classification and more than a 10% weight loss in the 6 months before surgery were associated with a high risk of complications. Conclusions Morbidity and mortality rates after the surgical treatment of appendicitis in VA hospitals are comparable with those reported in other large series. Most postsurgical complications are associated with an increased 30-day mortality rate. The models presented here are the most robust available in predicting 30-day morbidity and mortality for VA patients with appendicitis. Furthermore, they provide a starting point for the design of similar models to evaluate non-VA patients with appendicitis using the data the National Surgical Quality Improvement Program is currently gathering from private hospitals.

Comparison of outcome after valve replacement with a bioprosthesis versus a mechanical prosthesis: Initial 5 year results of a randomized trial

The Veterans Administration Cooperative Study on Valvular Heart Disease was organized to compare survival and incidence of valve-related complications between patients receiving a bioprosthesis (the Hancock porcine heterograft) and a mechanical prosthesis (the Björk-Shiley spherical disc valve). Five hundred seventy-five patients undergoing single aortic or mitral valve replacement were randomized at surgery to one of the two valve types. At an average follow-up of 5 years (range 3 to 8) there are no statistically significant differences in survival between patients with the two valve types in the aortic valve replacement group. There is a statistically nonsignificant trend toward improved survival in patients undergoing mitral valve replacement with a bioprosthesis compared with a mechanical prosthesis (5 year survival probability was 0.70 +/- 0.05 and 0.58 +/- 0.06, respectively). Fatal and nonfatal valve-related complications occurred significantly less frequently in patients with a bioprosthesis compared with a mechanical prosthesis for both mitral and aortic valve replacement. Five year complication-free probability was 0.67 +/- 0.05 and 0.45 +/- 0.06, respectively, for patients with mitral valve replacement and 0.63 +/- 0.04 and 0.53 +/- 0.04, respectively, for those with aortic valve replacement. The difference in overall complication rates was largely due to the increased number of clinically significant but nonfatal bleeding episodes in patients receiving a mechanical prosthesis. Adjustment for differences in baseline characteristics between patients receiving a mitral mechanical prosthesis and a mitral bioprosthesis reduced the statistical significance of the difference in both mortality and complications.