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Results for “Propensity Score”

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PubMed2004

Operative mortality after conventional versus coronary revascularization without cardiopulmonary bypass.

OBJECTIVE: Off-pump coronary artery bypass (CABG) is a safe revascularization option with comparable or superior results to the conventional on-pump CABG. However, comparative analysis of the type of surgical approach on the mortality rate is largely unknown. This study sought to investigate whether CABG without cardiopulmonary bypass (off-pump CABG) is associated with lower operative mortality than the conventional on-cardiopulmonary bypass (on-pump) approach. METHODS: From October 1998 to June 2001, off-pump CABG was performed on 2477 patients and on-pump CABG was performed on 3077 patients. The patients undergoing off-pump CABG were randomly matched to on-pump patients via propensity score. Seventy-four percent of the off-pump CABG patients were matched with on-pump patients via propensity scores. A logistic regression model was used to test the difference in the postoperative mortality rate between off-pump CABG and on-pump CABG, controlling the correlation between matched sets. A multiple logistic regression model predicting the risk of mortality adjusted by risk factors of mortality and operation type was computed. RESULTS: Results from the general estimating equation showed that patients who had on-pump CABG were 1.6 (95% confidence intervals (CI)=1.2-2.0, P<0.01) times more likely to die during the first 30 days after surgery than patients who had off-pump CABG. Independent predictors of 30-day mortality identified from the multiple logistic model included on-pump CABG (versus off-pump CABG), advanced age, female gender, carotid artery disease, chronic renal failure, depressed ejection fraction, reoperative CABG, preoperative intraaortic balloon counterpulsation, and recent myocardial infarction. CONCLUSION: Excellent clinical results and a lower operative mortality rate can be achieved with the off-pump CABG technique compared with the conventional on-pump approach.

Aged↗

PubMed2006

The valve of choice in elderly patients and its influence on quality of life: a long-term comparative study.

BACKGROUND AND AIM OF THE STUDY: Mechanical heart valves are preferred for younger patients in order to avoid valve structural deterioration, but bioprosthetic valves are favored for older patients to avoid long-term anticoagulation. With increasing patient longevity, controversy persists regarding the valve of choice in the 65- to 75-year-old population. With improving patient survival, long-term quality of life (QOL) is a critical element in helping to resolve this controversy. METHODS: A retrospective analysis was conducted of 1,104 consecutive patients, aged 65-75 years, who underwent valve replacement between July 1976 and December 1999. Valves implanted were either a Carpentier-Edwards (CE) porcine bioprosthesis (596 patients) or a St. Jude Medical (SJM) mechanical valve (508 patients), with and without concomitant coronary artery bypass grafting. QOL was assessed using the Short Form (SF-36) Health Survey for both groups at the time of follow up, which was 98.2% complete. Comparable patient groups were analyzed within quintiles by propensity score analysis. RESULTS: Operative mortality was 9.4% (n = 56) for CE patients, and 5.3% (n = 27) for SJM patients (p = 0.014). Propensity score analysis revealed no significant difference in operative mortality between groups in any of the five quintiles. Actuarial survival for hospital survivors favored SJM patients (p = 0.005). However, when compared within quintiles, there was no significant difference between groups. QOL summary scores were significantly higher for physical health (p = 0.007) for SJM patients, but similar between valve groups for mental health. Comparison within quintiles revealed no significant difference between the groups in either area. CONCLUSION: When comparing the outcomes of mechanical versus bioprosthetic valve replacement, considerable care must be exercised to ensure the clinically relevant similarity of groups. When evaluating comparable patient groups, there was no advantage in either survival or QOL for patients aged 65-75 years receiving a CE or SJM valve.

Aged↗

PubMed2005

Costs associated with the management of overactive bladder and related comorbidities.

STUDY OBJECTIVE: To evaluate the clinical and economic impact of overactive bladder (OAB) on the management of related comorbidities in a managed care population. DESIGN: Retrospective analysis of a claims database. SETTING: A large managed care organization in the United States. PATIENTS: A total of 11,556 patients with OAB who were aged 18 years or older and 11,556 control subjects without OAB who were matched on propensity score. MEASUREMENTS AND MAIN RESULTS: Patients and controls were identified from July 1-December 31, 2001, and followed for 360 days. The propensity score for matching controls was estimated based on patient demographics and diagnosis of important clinical conditions during a 180-day preindex period. Medical claims were examined for any diagnosis of the studied comorbidities. Submitted medical charges for claims with a primary or secondary diagnosis of the studied comorbidities were analyzed. Prevalence and medical charges for depression, skin infections, and vulvovaginitis were compared between patients with OAB and control subjects by using chi2 and t tests. Prevalence and medical charges for falls and fractures, urinary tract infections (UTIs), and any comorbidity were compared by using logistic regression and general linear modeling, to adjust for additional confounders not included in the matching process. Prevalence of all comorbid conditions was significantly higher (p<0.0001) for patients with OAB than for control subjects: falls and fractures, 25.3% versus 16.1%; depression, 10.5% versus 4.9%; UTIs, 28.0% versus 8.4%; skin infections, 3.9% versus 2.3%; vulvovaginitis, 4.7% versus 1.8%; any of these comorbidities, 52.1% versus 27.9%. Mean annual medical charges were significantly higher for patients than for controls for all comorbidities: falls and fractures, $934 versus $598 (p<0.0001); depression, $93 versus $23 (p<0.0001); UTIs, $603 versus $176 (p<0.0001); skin infections, $67 versus $10 (p=0.002); vulvovaginitis, $11 versus $3 (p<0.0001); any comorbidity, $1689 versus $829 (p<0.0001). CONCLUSION: This study quantifies the increased prevalence of and additional medical costs associated with related comorbidities in patients with OAB, emphasizing that the economic and clinical impact of OAB extends beyond the disease itself. Thus, management of patients with OAB should be of greater focus with both clinicians and health care payers.

Aged↗

PubMed2006

Preservation of pleural integrity in patients undergoing coronary artery bypass grafting: effect on postoperative bleeding and respiratory function.

OBJECTIVE: The purpose of this study was to evaluate the influence of preserved integrity of pleura on postoperative bleeding and respiratory function in patients undergoing coronary artery bypass grafting (CABG). METHODS AND RESULTS: Seventy-two CABG patients who received pedunculated IMA graft without opening the pleura (group of intact pleura, group IP) between July 2002 and September 2004 were matched to 72 CABG patients who received pedunculated IMA graft with opened pleura (group of opened pleura, group OP). To match the patients with IP and unique patients with OP, logistic regression was used to develop a propensity score. The C statistic for this model was 0.79. Patients with IP were matched to unique patients with OP with an identical 5-digit propensity score. If this could not be done, we proceeded to a 4-, 3-, 2-, or 1-digit match. Patients characteristics were well matched. There were no differences in preoperative and peroperative variables between the groups. The incidence of postoperative pleural effusion and thoracentesis were significantly lower in group IP than group OP (pleural effusion in 15.2 versus 30.5%; p = 0.029, thoracentesis in 5.5 versus 18.5%; p = 0.036). Other pulmonary complications such as prolonged ventilation, reintubation, pneumothorax, atelectasis, diaphragmatic paralysis were similar in both groups. Patients with IP had significantly lower blood loss (520 versus 870 ml; p < 0.001) and whole blood unit transfusion (26.3 versus 41.6%, p = 0.036). Also, intensive care unit and hospital stay were similar in both groups. CONCLUSIONS: Meticulous internal mammary artery harvesting and preservation of the pleural integrity significantly reduces postoperative bleeding and pleural effusion.

Chi-Square Distribution↗

PubMed2006

Microvolt T-wave alternans identifies patients with ischemic cardiomyopathy who benefit from implantable cardioverter-defibrillator therapy.

OBJECTIVES: This study sought to assess whether implantable cardioverter-defibrillators (ICDs) have different mortality benefits among patients with ischemic cardiomyopathy who screen negative and non-negative (positive and indeterminate) for microvolt T-wave alternans (MTWA). BACKGROUND: Microvolt T-wave alternans has been proposed as an effective tool for risk stratification. However, no studies have examined whether ICD benefits differ by MTWA group. METHODS: We developed a prospective cohort of 768 patients with ischemic cardiomyopathy (left ventricular ejection fraction < or =35%) and no prior sustained ventricular arrhythmia, of which 392 (51%) received ICDs. The mean follow-up time was 27 +/- 12 months. Propensity scores for ICD implantation based on the variables most likely to influence defibrillator implantation were developed for each MTWA cohort. Multivariable Cox analyses that controlled for propensity score, demographics, and clinical variables evaluated the degree to which ICDs decreased mortality risk for each MTWA group. RESULTS: We identified 514 (67%) patients with a non-negative MTWA test result. After multivariable adjustment, ICDs were associated with lower all-cause mortality in MTWA-non-negative patients (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.27 to 0.76, p = 0.003) but not in MTWA-negative patients (HR 0.85, 95% CI 0.33 to 2.20, p = 0.73) (for interaction, p = 0.04), with the mortality benefit in MTWA-non-negative patients largely mediated through arrhythmic mortality reduction (HR 0.30, 95% CI 0.13 to 0.68, p = 0.004). The number needed to treat with an ICD for 2 years to save 1 life was 9 among MTWA-non-negative patients and 76 among MTWA-negative patients. CONCLUSIONS: In patients with ischemic cardiomyopathy and no prior history of ventricular arrhythmia, mortality reduction with ICD implantation differs by MTWA status, with implications for risk stratification and health policy.

Aged↗

PubMed2007

The design versus the analysis of observational studies for causal effects: parallels with the design of randomized trials.

For estimating causal effects of treatments, randomized experiments are generally considered the gold standard. Nevertheless, they are often infeasible to conduct for a variety of reasons, such as ethical concerns, excessive expense, or timeliness. Consequently, much of our knowledge of causal effects must come from non-randomized observational studies. This article will advocate the position that observational studies can and should be designed to approximate randomized experiments as closely as possible. In particular, observational studies should be designed using only background information to create subgroups of similar treated and control units, where 'similar' here refers to their distributions of background variables. Of great importance, this activity should be conducted without any access to any outcome data, thereby assuring the objectivity of the design. In many situations, this objective creation of subgroups of similar treated and control units, which are balanced with respect to covariates, can be accomplished using propensity score methods. The theoretical perspective underlying this position will be presented followed by a particular application in the context of the US tobacco litigation. This application uses propensity score methods to create subgroups of treated units (male current smokers) and control units (male never smokers) who are at least as similar with respect to their distributions of observed background characteristics as if they had been randomized. The collection of these subgroups then 'approximate' a randomized block experiment with respect to the observed covariates.

Biometry↗

PubMed2006

Health outcomes in older men with localized prostate cancer: results from the Prostate Cancer Outcomes Study.

PURPOSE: We compared health-related quality-of-life (HRQOL) outcomes and survival of men with localized prostate cancer who received aggressive treatment with those receiving conservative management. METHODS: We conducted a population-based cohort study of men aged 75 to 84 years when diagnosed with a clinically localized cancer in 1994 or 1995. We used medical record abstractions and patient surveys to obtain clinical and HRQOL data at diagnosis and 24-month follow-up. We used a propensity score method to adjust for baseline differences between men treated with radical prostatectomy or radiation therapy (n = 175) and men who received hormone therapy or no treatment (n = 290). Propensity scores were used in regression analyses comparing HRQOL outcomes between treatment groups. Overall and disease-specific survivals were estimated with multivariate proportional hazards models. RESULTS: At 24 months following diagnosis, aggressively treated men were more likely to report daily urinary leakage (odds ratio [OR] = 2.9, 95% confidence interval [CI] 1.2-7.0) and to be bothered by urinary problems (OR = 5.1, 95% CI, 1.3-9.1) and sexual problems (OR = 2.8, 95% CI, 1.2-6.3). The adjusted disease-specific mortality hazard ratio was 0.43 (95% CI, 0.15, 1.28), favoring aggressive treatment. However, the absolute 5-year disease-specific survival difference was only 6% (98% vs 92%). Over 80% of all deaths were from other causes. CONCLUSIONS: Aggressive treatment was associated with significant decreases in disease-specific HRQOL. However, men who were aggressively treated for localized cancer had a minimally reduced absolute risk of dying from prostate cancer. Physicians and older patients should consider these outcomes in making decisions about screening and treatment.

Age Factors↗

PubMed2003

Effect of preoperative aspirin use in off-pump coronary artery bypass operations.

BACKGROUND: The effect of preoperative aspirin use until the day of operation on mortality rate and bleeding risks in patients who had on-pump coronary artery bypass operation has been well documented. However, the effect of aspirin use in patients undergoing off-pump coronary artery bypass operation (OPCAB) with regard to postoperative blood loss and morbidity has not been studied. We aimed to determine the effects of continuing aspirin therapy preoperatively. METHODS: We performed a retrospective study of 340 patients who had first-time OPCAB between January 1998 and September 2001. A propensity score for receiving aspirin until the day of operation was constructed from core patient characteristics. All aspirin users (n = 170) were matched with unique 170 nonaspirin users by identical propensity score. The primary outcome measures were in-hospital mortality rate and hemorrhage-related outcomes (postoperative blood loss in the intensive care unit, reexploration for bleeding, and blood product requirements). Secondary outcome measures were stroke, myocardial infarction, gastrointestinal bleeding, and sternal wound infections. RESULTS: There were no differences in patient characteristics between aspirin users and nonaspirin users. The average postoperative blood loss (845 mL versus 775 mL; p = 0.157) and the rate of reexploration for bleeding (3.5% versus 3.5%; p > 0.99) were similar in aspirin users and nonaspirin users. We found no significant difference between blood product requirements for the two groups. Similarly, we found no significant difference in the incidence of the secondary outcomes. CONCLUSIONS: Preoperative aspirin did not increase bleeding-related complications, mortality rate, or other morbidities in patients who had off-pump coronary artery operation.

Aged↗

PubMed2006

Screening for multidrug-resistant bacteria as a predictive test for subsequent onset of nosocomial infection.

OBJECTIVE: To investigate whether carriage of multidrug-resistant bacteria is a risk factor for nosocomial infection and whether detection of carriage is predictive of subsequent onset of nosocomial infection. METHODS: In this observational cohort (study period, June 1998 through October 2002), nasal and rectal swab specimens from 412 consecutive patients admitted to the intensive care unit were tested for carriage of multidrug-resistant bacteria. Concomitantly, the bacteria responsible for any subsequent nosocomial infection, the date of infection, and some of the known clinical risk factors for nosocomial infection were noted. These factors were adjusted for potential confounders, using a Cox model stratified on the propensity score of multidrug-resistant bacteria carriage. The diagnostic characteristics of a carriage test, including the positive and negative diagnostic likelihood ratios, were calculated for all strata of the propensity score. RESULTS: Forty-two patients were carrying multidrug-resistant bacteria. Nosocomial infection occurred in 95 patients, of whom 16 (38%) were carriers, and 79 (83%) were noncarriers (P=.01). After adjustment for potential confounders, statistical analysis revealed that carriage remained a risk factor for nosocomial infection (relative risk, 2.08 [95% confidence interval {CI}, 1.13-3.81]). Receipt of antibiotic treatment at the time of intensive care unit admission was found to be protective against nosocomial infection. A positive result of test for detection of carriage seemed to be an efficient predictor of subsequent nosocomial infection (positive diagnostic likelihood ratio, 2.05 [95% CI, 1.15-3.66]), although a negative test result was not a predictor of subsequent nosocomial infection (negative likelihood ratio, 0.91 [95% CI, 0.73-1.11]). CONCLUSION: Carriage proved to be a risk factor for subsequent nosocomial infection. However, the carriage test was useful as a predictive tool only for patients with a positive test result.

Aged↗

PubMed2003

The influence of cardiopulmonary bypass flow characteristics on the clinical outcome of 1820 coronary bypass patients.

OBJECTIVE: To determine whether pulsatile perfusion is clinically beneficial for adult cardiac operations. METHODS: Data concerning consecutive patients undergoing isolated coronary bypass surgery (n=1820) from January 1, 1997 to July 31, 1999 were reviewed. RESULTS: Nine hundred fifteen patients received pulsatile perfusion (PP) while perfusion in the remaining 905 patients was nonpulsatile (NP). Patients in the PP group were older (64.0 +/- 9.2 years versus 63.1 +/- 9.9 years) and experienced more of the following: urgent operations (42.4% versus 38.0%), preoperative intra-aortic balloon pump (4.8% versus 1.8%), preoperative cerebrovascular accidents (CVA; 3.1% versus 1.3%) and renal insufficiency (10.5% versus 7.0%). The PP group had higher incidence of early postoperative mortality (2.6% versus 1.5%), CVA (3.1% versus 1.3%), need for dialysis (3.2% versus 2.2%) and longer hospital stay (9.2 +/- 8.3 days versus 8.5 +/- 5.8 days). The incidence of postoperative myocardial infarction and renal dysfunction was similar in both groups (2.0% versus 2.2% and 3.3% versus 3.9% respectively; not significant). Because of the significant difference in preoperative parameters for the PP and NP groups, the following three statistical techniques were used to isolate the effect of perfusion characteristics on operative outcome: multiple regression, propensity score and risk stratification. Multivariate analysis did not find PP to be protective against mortality, morbidity and mortality, and CVA or for the development of postoperative renal dysfunction. When propensity score analysis was applied, the incidence of cardiac morbidity and mortality was strongly associated with the quintile (first quintile 6.7%, fifth quintile 27.0%, P<0.001). Multivariate analysis including quintiles did not find PP to be an independent predictor for mortality or for morbidity and mortality. Risk stratification was performed for age and for preoperative creatinine clearance levels. In all groups, PP did not seem to reduce the incidence of morbidity, morbidity and mortality, or the development of postoperative renal dysfunction. In patients with preoperative renal dysfunction, mean postoperative creatinine levels and the need for dialysis following surgery were similar in the PP and NP groups. CONCLUSION: Pulsatile flow does not appear to offer any clinical benefit over nonpulsatile flow for cardiac surgery patients.

Aged↗

PubMed2006

Emergency coronary artery bypass graft surgery for acute coronary syndrome: beating heart versus conventional cardioplegic cardiac arrest strategies.

BACKGROUND: Aim of this study was to compare the outcome of beating heart versus conventional coronary artery bypass graft (CABG) strategies in acute coronary syndromes for emergency indications. METHODS AND RESULTS: 638 consecutive patients with acute coronary syndrome (ACS) receiving emergency CABG surgery via midline sternotomy from January 2000 to September 2005 were evaluated. Propensity score analysis was used to predict the probability of undergoing beating heart (BH) (n=240) versus cardioplegic cardiac arrest (CA) (n=398) strategies. Patients presented with stable hemodynamics (n=531) or in cardiogenic shock (CS) (n=107). Hospital and follow-up outcome was compared by propensity score adjusted multiregression analysis. BH included 116 on-pump and 124 off-pump (OPCAB) procedures. There was a propensity to operate CS patients on the beating heart (multivariate odds ratio [OR], 3.8; P=0.001). Under stable hemodynamics significant predictors for BH selection were logEuroSCORE >20% (OR, 2.05), creatinine >1.8 mg/dL (OR, 4.12), complicated percutaneous coronary intervention (OR, 1.88), ejection fraction <30% (OR, 2.64), whereas left main disease (OR, 0.68), circumflex artery (OR, 0.32), and 3-vessel disease (OR, 0.67) indicated preference for cardioplegic arrest. Time from skin incision to culprit lesion revascularization was significantly reduced in BH patients. BH surgery led to a significant benefit in terms of less drainage loss, less transfusion requirement, less inotropic support, shorter ventilation time, lower stroke rate, and shorter intensive care unit stay. In CS, BH was associated with lower incidence of stroke, inotropic support, acute renal failure, new atrial fibrillation and sternal wound healing complications. In CS patients, hospital mortality rate was reduced when using beating heart strategies (P=0.048). Overall survival, major adverse cerebral and cardiovascular event rate, and repeated revascularization was comparable during a 5-year follow-up. CONCLUSIONS: Beating heart strategies are associated with an improved hospital outcome and comparable long-term results for high-risk patients presenting acute coronary syndrome with or without CS.

Adult↗

PubMed2004

Neighbourhood environments and mortality in an elderly cohort: results from the cardiovascular health study.

BACKGROUND: It has been postulated that neighbourhood conditions are related to the health of the elderly population but longitudinal studies are rare and confounding by individual level variables remains a possibility. METHODS: Data were obtained from the cardiovascular health study, a population based study of adults aged 65 years and older. Census block groups were used as proxies for neighbourhoods. A summary score was used to characterise the neighbourhood socioeconomic environment. Information on personal socioeconomic indicators, cardiovascular disease prevalence, and cardiovascular risk factors was obtained from the baseline examination. Proportional hazards regression and propensity score matching were used to control for individual level variables. RESULTS: Over the eight year follow up there were 1346 deaths among the 5074 participants, of which 43% were attributable to cardiovascular disease. Among white participants, living in the most disadvantaged neighbourhood group was associated with higher rates of cardiovascular death, after adjustment for income, education, and occupation (hazard ratio (HR) 1.5, 95% confidence intervals (CI) 1.2 to 1.9). No neighbourhood differences were observed for non-cardiovascular deaths. Estimates for black participants were 1.3 (95% CI 0.7 to 2.3) for cardiovascular deaths and 1.4 (95% CI 0.8 to 2.4) for non-cardiovascular deaths, but sample size was small. In white participants, associations of neighbourhood characteristics with cardiovascular mortality persisted after adjustment for prevalent baseline disease and cardiovascular risk factors. The use of propensity score matching led to similar results (HR for the lowest compared with the highest neighbourhood score group: 1.6 95% CI 1.1 to 2.5, controlling for personal socioeconomic indicators). CONCLUSION: Neighbourhood disadvantage is related to rates of cardiovascular death in elderly white adults.

Black or African American↗

PubMed2004

Impact of preoperative intravenous nitroglycerin on in-hospital outcomes after coronary artery bypass grafting for unstable angina.

BACKGROUND: Intravenous nitroglycerin (NTG) is an effective therapy for unstable angina (UA), but it may induce endothelial dysfunction and impair vascular nitric oxide signaling. We sought to determine whether preoperative intravenous NTG administration alters in-hospital outcomes in patients undergoing coronary artery bypass grafting (CABG) for UA. METHODS AND RESULTS: All in-hospital patients with Canadian Cardiovascular Society class IV angina who had isolated CABG between March 1995 and July 2002 at two Canadian centers were identified (n = 3976). Of these, 2506 were not receiving intravenous NTG and 1470 were receiving intravenous NTG at the time of CABG. Outcomes assessed were in-hospital mortality (IHM), intraoperative or postoperative aortic balloon pump use, perioperative myocardial infarction, prolonged (> or =24 hours) ventilation (p-vent), and a composite outcome, defined as any one or more of the above. Unadjusted IHM (5.9% vs 4.2%, P =.02), p-vent (22.2% vs 10.5%, P =.0001), and composite outcome (26.5% vs 15.2%, P =.0001) were higher in patients receiving intravenous NTG. Logistic regression showed that preoperative intravenous NTG was not an independent predictor of composite outcome (OR, 1.1; P =.49) or IHM (OR, 0.94; P =.69). Propensity score analysis was used to match two subgroups of patients (group 1, intravenous NTG, n = 1176; group 2, no intravenous NTG, n = 1176) on multiple factors. After adjustment with the propensity score, preoperative intravenous NTG use had no significant effect on any of the outcomes assessed. CONCLUSIONS: Despite its potential to induce endothelial dysfunction and impair vascular nitric oxide signaling, preoperative intravenous NTG administration is not associated with altered in-hospital outcomes after CABG for UA.

Aged↗

PubMed2007

Recent metformin ingestion does not increase in-hospital morbidity or mortality after cardiac surgery.

BACKGROUND: Perioperative treatment of type 2 diabetes with metformin, an oral hypoglycemic drug, is thought to increase the risk of life-threatening postoperative lactic acidosis. In contrast, metformin improves serum glucose control and has beneficial cardiovascular effects, which may decrease the risk of adverse outcomes. In this investigation we sought to determine the influence of metformin treatment on mortality and morbidity compared with treatment with other oral hypoglycemic drugs in diabetic patients undergoing cardiac surgery. METHODS: In this retrospective investigation, 1284 diabetic patients, with recent oral hypoglycemic ingestion (presumed to be 8-24 h preoperatively), underwent cardiac surgery from 1994-2004. Propensity scores were calculated from a logistic model which included baseline characteristics and perioperative variables. Four-hundred-forty-three (85%) of the metformin-treated patients were matched on nearest propensity score using greedy matching techniques with 443 nonmetformin-treated patients. Postoperative outcomes were compared between matched metformin- and nonmetformin-treated patients. RESULTS: In-hospital mortality, cardiac, renal, and neurologic morbidities were similar between groups. Metformin-treated patients had less postoperative prolonged tracheal intubation [OR (95% CI), 0.3 (0.1, 0.7), P = 0.003], infection [0.2 (0.1, 0.7), P = 0.007] and overall morbidities [0.4 (0.2, 0.8), P = 0.005]. CONCLUSIONS: These data suggest that recent metformin ingestion is not associated with increased risk of adverse outcome in cardiac surgical patients. Alternatively, metformin treatment may have beneficial effects.

Administration, Oral↗

PubMed2000

Outcomes monitoring and the testing of new psychiatric treatments: work therapy in the treatment of chronic post-traumatic stress disorder.

OBJECTIVE: To evaluate the effectiveness of a work therapy intervention, the Department of Veterans Affairs (VA) Compensated Work Therapy program (CWT), in the treatment of patients suffering from chronic war-related post-traumatic stress disorder (PTSD); and to demonstrate methods for using outcomes monitoring data to screen previously untested treatments. DATA SOURCES/STUDY SETTING: Baseline and four-month follow-up questionnaires administered to 3,076 veterans treated in 52 specialized VA inpatient programs for treatment of PTSD at facilities that also had CWT programs. Altogether 78 (2.5 percent) of these patients participated in CWT during the four months after discharge. STUDY DESIGN: The study used a pre-post nonequivalent control group design. DATA COLLECTION/EXTRACTION METHODS: Questionnaires documented PTSD symptoms, violent behavior, alcohol and drug use, employment status, and medical status at the time of program entry and four months after discharge from the hospital to the community. Administrative databases were used to identify participants in the CWT program. Propensity scores were used to match CWT participants and other patients, and hierarchical linear modeling was used to evaluate differences in outcomes between treatment groups on seven outcomes. PRINCIPAL FINDINGS: The propensity scaling method created groups that were not significantly different on any measure. No greater improvement was observed among CWT participants than among other patients on any of seven outcome measures. CONCLUSIONS: Substantively this study suggests that work therapy, as currently practiced in VA, is not an effective intervention, at least in the short term, for chronic, war-related PTSD. Methodologically it illustrates the use of outcomes monitoring data to screen previously untested treatments and the use of propensity scoring and hierarchical linear modeling to adjust for selection biases in observational studies.

Chronic Disease↗

PubMed2001

Early mortality and morbidity of bilateral versus single internal thoracic artery revascularization: propensity and risk modeling.

OBJECTIVES: We examined whether bilateral internal thoracic artery (BITA) revascularization is associated with any increased in-hospital mortality and complications compared with single internal thoracic artery (SITA) revascularization. BACKGROUND: Despite proven long-term benefits, BITA revascularization has been slow to be adopted because of fear of increased early morbidity. METHODS: We evaluated 1,697 consecutive patients undergoing BITA (n = 867) or SITA (n = 830) revascularization. We used propensity score analyses and adjusted risk models to address differences between arms. RESULTS: There were 20 (2.3%) deaths in the BITA group versus 26 (3.1%) in the SITA group (odds ratio 0.73, p = 0.30). Propensity analysis identified several parameters that affected the decision to use BITA. Adjusting for propensity score and all potential risk factors, the odds ratio for death with BITA versus SITA was practically 1. Bilateral internal thoracic artery revascularization did not increase the number of in-hospital complications with the possible exception of deep sternal wound infections (11 [1.3%] vs. 3 [0.4%], p = 0.057). In multivariate modeling BITA increased the risk of deep sternal wound infections only in emergent cases and in older patients; the excess risk was negligible among 1,206 patients (71.1% of total) who did not have emergent revascularization and were < or =70 years old (risk difference 0.3%, p = 0.74). There was no difference in length of stay after adjustment for propensity factors (mean 11.3 vs. 11.7 days, p = 0.66). CONCLUSIONS: Bilateral internal thoracic artery revascularization grafting confers no increased risk for early death and does not prolong hospital stay. The small increase in the risk of deep sternal wound infections does not affect the majority of patients.

Aged↗

PubMed2005

Total arterial revascularisation: effect of avoiding cardiopulmonary bypass on in-hospital mortality and morbidity in a propensity-matched cohort.

OBJECTIVE: The combination of total arterial revascularisation and avoidance of cardiopulmonary bypass may provide additional benefits to patients receiving complete arterial grafting with cardiopulmonary bypass. We performed a propensity-matched cohort study of complete arterial off-pump and on-pump coronary surgery and examined differences in in-hospital mortality and morbidity. METHODS: Three hundred and sixty patients who underwent off-pump coronary surgery with complete arterial grafting between April 1997 and September 2002 were matched to 360 patients who received coronary surgery with cardiopulmonary bypass and complete arterial grafting. To match off-pump with unique on-pump patients, logistic regression was used to develop a propensity score for off-pump surgery. The C statistic for this model was 0.79. Off-pump patients were matched to unique on-pump patients with an identical 5-digit propensity score. If this could not be done, we then proceeded to a 4-, 3-, 2-, or 1-digit match. RESULTS: Patient characteristics were well matched. There was no difference in in-hospital mortality between the groups. Off-pump patients were less likely to develop sternal wound infections compared to the on-pump group (2.5 versus 5.8%; P=0.03), and had significantly lower blood loss (675 versus 780 ml; P<0.001), red blood cell unit transfusion (8.6 versus 38.9%; P<0.001), enzyme rises (13 versus 23 U/l; P<0.001), inotrope support (11.9 versus 28.9%; P<0.001), and ventilation times (5 versus 8 h; P<0.001). Intensive care unit and hospital stay were also significantly lower in the off-pump patients. CONCLUSIONS: Off-pump coronary surgery with complete arterial revascularisation can significantly reduce in-hospital morbidity and lengths of stay compared to conventional on-pump coronary surgery.

Aged↗

PubMed2006

Preoperative statin therapy is associated with reduced cardiac mortality after coronary artery bypass graft surgery.

OBJECTIVE: Statin therapy in ambulatory populations is associated with a significant reduction in adverse cardiovascular events, including death and myocardial infarction. Much less is known about the beneficial effects of statins on acute perioperative cardiovascular events. The purpose of this study was to determine whether preoperative statin therapy is associated with a reduced risk of early cardiac death or nonfatal, in-hospital postoperative myocardial infarction after primary, elective coronary artery bypass graft surgery requiring cardiopulmonary bypass. METHODS: The Multicenter Study of Perioperative Ischemia (McSPI) Epidemiology II Study was a prospective, longitudinal study of 5436 patients undergoing coronary artery bypass graft surgery between November 1996 and June 2000 at 70 centers in 17 countries. The present study consisted of a pre-specified subset of these subjects divided into patients receiving (n = 1352) and not receiving (n = 1314) preoperative statin therapy. To control for potential bias related to use of statin therapy, the study estimated propensity scores by logistic regression to determine the predicted probability of inclusion in the "statin" group. Multivariate, stepwise logistic regression was then performed, controlling for patient demographics, medical history, operative characteristics, and propensity score to determine whether preoperative statin therapy was independently associated with a reduction in the risk of early (DOS-POD3) cardiac death and/or nonfatal, in-hospital postoperative myocardial infarction. RESULTS: Preoperative statin therapy was independently associated with a significant reduction (adjusted odds ratio [OR] 0.25; 95% confidence intervals [CI] 0.07-0.87) in the risk of early cardiac death after primary, elective coronary bypass surgery (0.3% vs 1.4%; P < .03), but was not associated with a reduced risk of postoperative nonfatal, in-hospital myocardial infarction (7.9% vs 6.2%; P = not significant). Discontinuation of statin therapy after surgery was independently associated with a significant increase in late (POD4-discharge) all-cause mortality (adjusted OR 2.64; 95% CI 1.32-5.26) compared with continuation of statin therapy (2.64% vs 0.60%; P < .01). This was true even when controlling for the postoperative discontinuation of aspirin, beta-blocker, or angiotensin-converting enzyme inhibitor therapy. Discontinuation of statin therapy after surgery was also independently associated with a significant increase in late cardiac mortality (adjusted OR 2.95; 95% CI 1.31-6.66) compared with continuation of statin therapy (1.91% vs 0.45%; P < 0.01). CONCLUSIONS: Preoperative statin use is associated with reduced cardiac mortality after primary, elective coronary artery bypass grafting. Postoperative statin discontinuation is associated with increased in-hospital mortality. Although further randomized trials are needed to confirm these findings, these data suggest the importance of perioperative statin administration.

Cardiopulmonary Bypass↗