Neuraxial block and postoperative epidural analgesia: effects on outcomes in the POISE-2 trial†

BACKGROUND

We assessed associations between intraoperative neuraxial block and postoperative epidural analgesia, and a composite primary outcome of death or non-fatal myocardial infarction, at 30 days post-randomization in POISE-2 Trial subjects.

METHODS

10 010 high-risk noncardiac surgical patients were randomized aspirin or placebo and clonidine or placebo. Neuraxial block was defined as intraoperative spinal anaesthesia, or thoracic or lumbar epidural anaesthesia. Postoperative epidural analgesia was defined as postoperative epidural local anaesthetic and/or opioid administration. We used logistic regression with weighting using estimated propensity scores.

RESULTS

Neuraxial block was not associated with the primary outcome [7.5% vs 6.5%; odds ratio (OR), 0.89; 95% CI (confidence interval), 0.73-1.08; P=0.24], death (1.0% vs 1.4%; OR, 0.84; 95% CI, 0.53-1.35; P=0.48), myocardial infarction (6.9% vs 5.5%; OR, 0.91; 95% CI, 0.74-1.12; P=0.36) or stroke (0.3% vs 0.4%; OR, 1.05; 95% CI, 0.44-2.49; P=0.91). Neuraxial block was associated with less clinically important hypotension (39% vs 46%; OR, 0.90; 95% CI, 0.81-1.00; P=0.04). Postoperative epidural analgesia was not associated with the primary outcome (11.8% vs 6.2%; OR, 1.48; 95% CI, 0.89-2.48; P=0.13), death (1.3% vs 0.8%; OR, 0.84; 95% CI, 0.35-1.99; P=0.68], myocardial infarction (11.0% vs 5.7%; OR, 1.53; 95% CI, 0.90-2.61; P=0.11], stroke (0.4% vs 0.4%; OR, 0.65; 95% CI, 0.18-2.32; P=0.50] or clinically important hypotension (63% vs 36%; OR, 1.40; 95% CI, 0.95-2.09; P=0.09).

CONCLUSIONS

Neuraxial block and postoperative epidural analgesia were not associated with adverse cardiovascular outcomes among POISE-2 subjects.

The Safety of Eplerenone in Hemodialysis Patients: A Noninferiority Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Mineralocorticoid receptor antagonism reduces morbidity and mortality in patients with heart failure, but the safety of these drugs in patients receiving dialysis is unclear. This study evaluated whether hyperkalemia and/or hypotension limited the use of eplerenone, a selective mineralocorticoid receptor antagonist, in hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a randomized controlled trial of prevalent patients receiving hemodialysis at five Canadian centers. Participants were randomly allocated to 13 weeks of eplerenone titrated to 50 mg daily (n=77) or a matching placebo (n=77). The primary outcome was permanent discontinuation of the drug because of hyperkalemia or hypotension. Secondary outcomes included hyperkalemia, hypotension, and cardiovascular events.

RESULTS

Seventy-five eplerenone-treated patients and 71 placebo-treated patients were included in the per protocol population. The primary outcome occurred in three patients (4.0%) in the eplerenone group and two (2.8%) in the placebo group, for an absolute risk difference of 1.2 percentage points (95% confidence interval, -4.7 to 7.1 percentage points). Eplerenone was interpreted as noninferior to placebo with respect to the primary outcome (i.e., a discontinuation rate for these reasons >10% was excluded). In the eplerenone group, nine patients (11.7%) developed hyperkalemia (potassium level >6.5 mEq/L), compared with two patients (2.6%) in the placebo group (relative risk, 4.5; 95% confidence interval, 1.0 to 20.2). There was no significant effect on predialysis or postdialysis BP.

CONCLUSION

Eplerenone increased the risk of hyperkalemia but did not result in an excess need to permanently discontinue the drug. Further trials are required to determine whether mineralocorticoid receptor antagonism improves cardiovascular outcomes in patients receiving long-term dialysis.

Postoperative atrial fibrillation in non-cardiac and cardiac surgery: an overview

Postoperative atrial fibrillation (POAF) is the most common perioperative cardiac arrhythmia. A major risk factor for POAF is advanced age, both in non-cardiac and cardiac surgery. Following non-cardiac surgery, it is important to correct reversible conditions such as electrolytes imbalances to prevent the occurrence of POAF. Management of POAF consists of rate control and therapeutic anticoagulation if POAF persists for > 48 h and CHADS2 score > 2. After cardiac surgery, POAF affects a larger amount of patients. In addition to age, valve surgery carries the greatest risk for new AF. Rate control is the mainstay therapy in these patients. Prediction, prevention, and management of POAF should be further studied.

Role of aspirin for prevention and treatment of perioperative cardiovascular events

Among adults undergoing non-cardiac surgery who are at risk of a myocardial infarction, a long-standing question has been whether these patients should receive aspirin throughout the perioperative period. A large (n = 10,010 patients) international trial (POISE-2) demonstrated that perioperative aspirin did not prevent myocardial infarction, and the result was consistent both for patients who had been taking aspirin before the trial (continuation stratum, 4382 patients) and for patients who had not been taking aspirin before the trial (initiation stratum, 5628 patients). Aspirin did, however, increase the risk of major bleeding. Therefore, the best evidence does not support the use of aspirin for the prevention of myocardial infarction in patients undergoing non-cardiac surgery. In patients who have an indication for long-term aspirin usage and have their aspirin held during the perioperative period, it is important to ensure aspirin is restarted after the high-risk period for bleeding has passed (i.e., 8-10 days after surgery).

Can troponin I measurement predict short-term serious cardiac outcomes in patients presenting to the emergency department with possible acute coronary syndrome?

Objective:

To determine the ability of troponin I (TnI) measurement to predict the likelihood of a serious cardiac outcome over the subsequent 72 hours in patients presenting to the emergency department (ED) with symptoms suggestive of an acute coronary syndrome.

Methods:

This prospective observational study enrolled consecutive patients presenting to 2 urban tertiary care hospital EDs over a 5-week period. Eligible patients included those for whom a TnI test was ordered within 24 hours of arrival and in whom no serious cardiac outcome occurred before the test result was available. Patients were followed for 72 hours and serious cardiac outcomes documented; these included cardiovascular death, myocardial infarction, congestive heart failure, serious arrhythmia and refractory pain. We calculated likelihood ratios (LRs) to describe the association of the TnI result with serious cardiac outcomes.

Results:

Of the 352 enrolled patients, 20 had a serious cardiac outcome within 72 hours of ED presentation. The derived LRs (and 95% confidence interval [CI]) were 0.5 (0.3–0.9) for TnI values <0.5 µg/L, 1.6 (0.4–6.5) for TnI values from 0.5 to 2.0 µg/L, 5.8 (1.7–19.5) for TnI values from >2.0 to 10.0 µg/L and 14.4 (4.8–42.9) for TnI values >10.0 µg/L.

Conclusions:

TnI values >2.0 µg/L are associated with an increased probability of serious cardiac outcomes within 72 hours. TnI values between 0.5 and 2.0 µg/L are weakly positive predictors. TnI values <0.5 µg/L have LRs in the range of 0.5 and thus are weakly negative predictors, not substantially decreasing the likelihood of serious cardiac outcomes, particularly in patients with a moderate or high pretest probability.

Reliability, validity, and responsiveness of the Western Ontario and McMaster Universities Osteoarthritis Index for elderly patients with a femoral neck fracture

BACKGROUND

The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) has been extensively evaluated in groups of patients with osteoarthritis, yet not in patients with a femoral neck fracture. This study aimed to determine the reliability, construct validity, and responsiveness of the WOMAC compared with the Short Form-12 (SF-12) and the EuroQol 5D (EQ-5D) questionnaires for the assessment of elderly patients with a femoral neck fracture.

METHODS

Reliability was tested by assessing the Cronbach alpha. Construct validity was determined with the Pearson correlation coefficient. Change scores were calculated from ten weeks to twelve months of follow-up. Standardized response means and floor and ceiling effects were determined. Analyses were performed to compare the results for patients less than eighty years old with those for patients eighty years of age or older.

RESULTS

The mean WOMAC total score was 89 points before the fracture in the younger patients and increased from 70 points at ten weeks to 81 points at two years postoperatively. In the older age group, these scores were 86, 75, and 78 points. The mean WOMAC pain scores before the fracture and at ten weeks and two years postoperatively were 92, 76, and 87 points, respectively, in the younger age group and 92, 84, and 93 points in the older age group. Function scores were 89, 68, and 79 points for the younger age group and 84, 71, and 73 points for the older age group. The Cronbach alpha for pain, stiffness, function, and the total scale ranged from 0.83 to 0.98 for the younger age group and from 0.79 to 0.97 for the older age group. Construct validity was good, with 82% and 79% of predefined hypotheses confirmed in the younger and older age groups, respectively. Responsiveness was moderate. No floor effects were found. Moderate to large ceiling effects were found for pain and stiffness scales at ten weeks and twelve months in younger patients (18% to 36%) and in the older age group (38% to 53%).

CONCLUSIONS

The WOMAC showed good reliability, construct validity, and responsiveness in both age groups of elderly patients with a femoral neck fracture who had been physically and mentally fit before the fracture. The instrument is suitable for use in future clinical studies in these populations.

CLINICAL RELEVANCE

The results are based on two clinical trials. The questionnaires used concern pure, clinically relevant issues (ability to walk, climb stairs, etc.). Moreover, the results can be used for future research comparing clinical outcomes (or treatments) for populations with a femoral neck fracture.

Prognostic capabilities of coronary computed tomographic angiography before non-cardiac surgery: prospective cohort study

OBJECTIVES

To determine if coronary computed tomographic angiography enhances prediction of perioperative risk in patients before non-cardiac surgery and to assess the preoperative coronary anatomy in patients who experience a myocardial infarction after non-cardiac surgery.

DESIGN

Prospective cohort study.

SETTING

12 centers in eight countries.

PARTICIPANTS

955 patients with, or at risk of, atherosclerotic disease who underwent non-cardiac surgery.

INTERVENTIONS

Coronary computed tomographic angiography was performed preoperatively; clinicians were blinded to the results unless left main disease was suspected. Results were classified as normal, non-obstructive (<50% stenosis), obstructive (one or two vessels with ≥ 50% stenosis), or extensive obstructive (≥ 50% stenosis in two vessels including the proximal left anterior descending artery, three vessels, or left main).

MAIN OUTCOME MEASURE

Composite of cardiovascular death and non-fatal myocardial infarction within 30 days after surgery (primary outcome). This was the dependent variable in Cox regression. The independent variables were scores on the revised cardiac risk index and findings on coronary computed tomographic angiography.

RESULTS

The primary outcome occurred in 74 patients (8%). The model that included both scores on the revised cardiac risk index and findings on coronary computed tomographic angiography showed that coronary computed tomographic angiography provided independent prognostic information (P=0.014; C index=0.66). The adjusted hazard ratios were 1.51 (95% confidence interval 0.45 to 5.10) for non-obstructive disease; 2.05 (0.62 to 6.74) for obstructive disease; and 3.76 (1.12 to 12.62) for extensive obstructive disease. For the model with coronary computed tomographic angiography compared with the model based on the revised cardiac risk index alone, with 30 day risk categories of <5%, 5-15%, and >15% for the primary outcome, the results of risk reclassification indicate that in a sample of 1000 patients that coronary computed tomographic angiography would have resulted appropriately in 17 net patients receiving a higher risk estimation among the 77 patients who would have experienced the primary outcome (P<0.001). Coronary computed tomographic angiography, however, would have resulted inappropriately in 98 net patients receiving a higher risk estimation, among the 923 patients who would not have experienced the primary outcome (P<0.001). Among patients who had a perioperative myocardial infarction, preoperative coronary anatomy showed extensive obstructive disease in 31% (22/71), obstructive disease in 41% (29/71), non-obstructive disease in 24% (17/71), and normal findings in 4% (3/71).

CONCLUSIONS

Though findings on coronary computed tomographic angiography can improve estimation of risk for patients who will experience perioperative cardiovascular death or myocardial infarction, findings are more than five times as likely to lead to an inappropriate overestimation of risk among patients who will not experience these outcomes. Perioperative myocardial infarction occurs across the spectrum of coronary artery disease, suggesting that there could be several pathophysiologic mechanisms.

Hip fracture evaluation with alternatives of total hip arthroplasty versus hemiarthroplasty (HEALTH): protocol for a multicentre randomised trial

INTRODUCTION

Hip fractures are a leading cause of mortality and disability worldwide, and the number of hip fractures is expected to rise to over 6 million per year by 2050. The optimal approach for the surgical management of displaced femoral neck fractures remains unknown. Current evidence suggests the use of arthroplasty; however, there is lack of evidence regarding whether patients with displaced femoral neck fractures experience better outcomes with total hip arthroplasty (THA) or hemiarthroplasty (HA). The HEALTH trial compares outcomes following THA versus HA in patients 50 years of age or older with displaced femoral neck fractures.

METHODS AND ANALYSIS

HEALTH is a multicentre, randomised controlled trial where 1434 patients, 50 years of age or older, with displaced femoral neck fractures from international sites are randomised to receive either THA or HA. Exclusion criteria include associated major injuries of the lower extremity, hip infection(s) and a history of frank dementia. The primary outcome is unplanned secondary procedures and the secondary outcomes include functional outcomes, patient quality of life, mortality and hip-related complications-both within 2 years of the initial surgery. We are using minimisation to ensure balance between intervention groups for the following factors: age, prefracture living, prefracture functional status, American Society for Anesthesiologists (ASA) Class and centre number. Data analysts and the HEALTH Steering Committee are blinded to the surgical allocation throughout the trial. Outcome analysis will be performed using a χ(2) test (or Fisher's exact test) and Cox proportional hazards modelling estimate. All results will be presented with 95% CIs.

ETHICS AND DISSEMINATION

The HEALTH trial has received local and McMaster University Research Ethics Board (REB) approval (REB#: 06-151).

RESULTS

Outcomes from the primary manuscript will be disseminated through publications in academic journals and presentations at relevant orthopaedic conferences. We will communicate trial results to all participating sites. Participating sites will communicate results with patients who have indicated an interest in knowing the results.

TRIAL REGISTRATION NUMBER

The HEALTH trial is registered with clinicaltrials.gov (NCT00556842).

Perioperative aspirin and clonidine and risk of acute kidney injury: a randomized clinical trial

IMPORTANCE

Acute kidney injury, a common complication of surgery, is associated with poor outcomes and high health care costs. Some studies suggest aspirin or clonidine administered during the perioperative period reduces the risk of acute kidney injury; however, these effects are uncertain and each intervention has the potential for harm.

OBJECTIVE

To determine whether aspirin compared with placebo, and clonidine compared with placebo, alters the risk of perioperative acute kidney injury.

DESIGN, SETTING, AND PARTICIPANTS

A 2 × 2 factorial randomized, blinded, clinical trial of 6905 patients undergoing noncardiac surgery from 88 centers in 22 countries with consecutive patients enrolled between January 2011 and December 2013.

INTERVENTIONS

Patients were assigned to take aspirin (200 mg) or placebo 2 to 4 hours before surgery and then aspirin (100 mg) or placebo daily up to 30 days after surgery, and were assigned to take oral clonidine (0.2 mg) or placebo 2 to 4 hours before surgery, and then a transdermal clonidine patch (which provided clonidine at 0.2 mg/d) or placebo patch that remained until 72 hours after surgery.

MAIN OUTCOMES AND MEASURES

Acute kidney injury was primarily defined as an increase in serum creatinine concentration from the preoperative concentration by either an increase of 0.3 mg/dL or greater (≥26.5 μmol/L) within 48 hours of surgery or an increase of 50% or greater within 7 days of surgery.

RESULTS

Aspirin (n = 3443) vs placebo (n = 3462) did not alter the risk of acute kidney injury (13.4% vs 12.3%, respectively; adjusted relative risk, 1.10; 95% CI, 0.96-1.25). Clonidine (n = 3453) vs placebo (n = 3452) did not alter the risk of acute kidney injury (13.0% vs 12.7%, respectively; adjusted relative risk, 1.03; 95% CI, 0.90-1.18). Aspirin increased the risk of major bleeding. In a post hoc analysis, major bleeding was associated with a greater risk of subsequent acute kidney injury (23.3% when bleeding was present vs 12.3% when bleeding was absent; adjusted hazard ratio, 2.20; 95% CI, 1.72-2.83). Similarly, clonidine increased the risk of clinically important hypotension. In a post hoc analysis, clinically important hypotension was associated with a greater risk of subsequent acute kidney injury (14.3% when hypotension was present vs 11.8% when hypotension was absent; adjusted hazard ratio, 1.34; 95% CI, 1.14-1.58).

CONCLUSIONS AND RELEVANCE

Among patients undergoing major noncardiac surgery, neither aspirin nor clonidine administered perioperatively reduced the risk of acute kidney injury.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01082874.

Rationale and design of a randomized controlled trial evaluating community health worker-based interventions for the secondary prevention of acute coronary syndromes in India (SPREAD)

BACKGROUND

There is a need to evaluate and implement cost-effective strategies to improve adherence to treatments in coronary heart disease. There are no studies from low- to middle income countries (LMICs) evaluating trained community health worker (CHW)-based interventions for the secondary prevention of coronary heart disease.

METHODS

We designed a hospital-based, open randomized trial of CHW-based interventions versus standard care. Patients after an acute coronary syndrome (ACS) were randomized to an intervention group (a CHW-based intervention package, comprising education tools to enhance self-care and adherence, and regular follow-up by the CHW) or to standard care for 12 months during which study outcomes were recorded. The CHWs were trained over a period of 6 months. The primary outcome measure was medication adherence. The secondary outcomes were differences in adherence to lifestyle modification, physiological parameters (blood pressure [BP], body weight, body mass index [BMI], heart rate, lipids), and major adverse cardiovascular events.

RESULTS

We recruited 806 patients stabilized after an ACS from 14 hospitals in 13 Indian cities. The mean age was 56.4 (± 11.32) years, and 17.2% were females. A high prevalence of risk factors such as hypertension (43.4%), diabetes (31.9%), tobacco consumption (35.4%), and inadequate physical activity (70.5%) was documented. A little over half had ST-elevation myocardial infarction (53.7%), and 46.3% had non-ST-elevation myocardial infarction or unstable angina.

CONCLUSION

The CHW interventions and training for SPREAD have been developed and adapted for local use. The results and experience of this study will be important to counter the burden of cardiovascular diseases in low- to middle income countries.

The safety of addition of nitrous oxide to general anaesthesia in at-risk patients having major non-cardiac surgery (ENIGMA-II): a randomised, single-blind trial

BACKGROUND

Nitrous oxide is commonly used in general anaesthesia but concerns exist that it might increase perioperative cardiovascular risk. We aimed to gather evidence to establish whether nitrous oxide affects perioperative cardiovascular risk.

METHODS

We did an international, randomised, assessor-blinded trial in patients aged at least 45 years with known or suspected coronary artery disease having major non-cardiac surgery. Patients were randomly assigned via automated telephone service, stratified by site, to receive a general anaesthetic with or without nitrous oxide. Attending anaesthetists were aware of patients' group assignments, but patients and assessors were not. The primary outcome measure was a composite of death and cardiovascular complications (non-fatal myocardial infarction, stroke, pulmonary embolism, or cardiac arrest) within 30 days of surgery. Our modified intention-to-treat population included all patients randomly assigned to groups and undergoing induction of general anaesthesia for surgery. This trial is registered at ClinicalTrials.gov, number NCT00430989.

FINDINGS

Of 10,102 eligible patients, we enrolled 7112 patients between May 30, 2008, and Sept 28, 2013. 3543 were assigned to receive nitrous oxide and 3569 were assigned not to receive nitrous oxide. 3483 patients receiving nitrous oxide and 3509 not receiving nitrous oxide were assessed for the primary outcome. The primary outcome occurred in 283 (8%) patients receiving nitrous oxide and in 296 (8%) patients not receiving nitrous oxide (relative risk 0·96, 95% CI 0·83–1·12; p=0·64). Surgical site infection occurred in 321 (9%) patients assigned to nitrous oxide, and in 311 (9%) patients in the no-nitrous oxide group (p=0·61), and severe nausea and vomiting occurred in 506 patients (15%) assigned to nitrous oxide and 378 patients (11%) not assigned to nitrous oxide (p<0·0001).

INTERPRETATION

Our findings support the safety profile of nitrous oxide use in major non-cardiac surgery. Nitrous oxide did not increase the risk of death and cardiovascular complications or surgical-site infection, the emetogenic effect of nitrous oxide can be controlled with antiemetic prophylaxis, and a desired effect of reduced volatile agent use was shown.

FUNDING

Australian National Health and Medical Research Council; Australian and New Zealand College of Anaesthetists; Heart and Stroke Foundation of Quebec, Heart and Stroke Foundation of Ontario, Canada; General Research Fund of the Research Grant Council, Hong Kong Special Administrative Region, China.

Immune biomarkers predictive of respiratory viral infection in elderly nursing home residents

OBJECTIVE

To determine if immune phenotypes associated with immunosenescence predict risk of respiratory viral infection in elderly nursing home residents.

METHODS

Residents ≥ 65 years from 32 nursing homes in 4 Canadian cities were enrolled in Fall 2009, 2010 and 2011, and followed for one influenza season. Following influenza vaccination, peripheral blood mononuclear cells (PBMCs) were obtained and analysed by flow cytometry for T-regs, CD4+ and CD8+ T-cell subsets (CCR7+CD45RA+, CCR7-CD45RA+ and CD28-CD57+) and CMV-reactive CD4+ and CD8+ T-cells. Nasopharyngeal swabs were obtained and tested for viruses in symptomatic residents. A Cox proportional hazards model adjusted for age, sex and frailty, determined the relationship between immune phenotypes and time to viral infection.

RESULTS

1072 residents were enrolled; median age 86 years and 72% female. 269 swabs were obtained, 87 were positive for virus: influenza (24%), RSV (14%), coronavirus (32%), rhinovirus (17%), human metapneumovirus (9%) and parainfluenza (5%). In multivariable analysis, high T-reg% (HR 0.41, 95% CI 0.20-0.81) and high CMV-reactive CD4+ T-cell% (HR 1.69, 95% CI 1.03-2.78) were predictive of respiratory viral infection.

CONCLUSIONS

In elderly nursing home residents, high CMV-reactive CD4+ T-cells were associated with an increased risk and high T-regs were associated with a reduced risk of respiratory viral infection.

Clinical outcomes with β-blockers for myocardial infarction: a meta-analysis of randomized trials

BACKGROUND

Debate exists about the efficacy of β-blockers in myocardial infarction and their required duration of usage in contemporary practice.

METHODS

We conducted a MEDLINE/EMBASE/CENTRAL search for randomized trials evaluating β-blockers in myocardial infarction enrolling at least 100 patients. The primary outcome was all-cause mortality. Analysis was performed stratifying trials into reperfusion-era (> 50% undergoing reperfusion or receiving aspirin/statin) or pre-reperfusion-era trials.

RESULTS

Sixty trials with 102,003 patients satisfied the inclusion criteria. In the acute myocardial infarction trials, a significant interaction (Pinteraction = .02) was noted such that β-blockers reduced mortality in the pre-reperfusion (incident rate ratio [IRR] 0.86; 95% confidence interval [CI], 0.79-0.94) but not in the reperfusion era (IRR 0.98; 95% CI, 0.92-1.05). In the pre-reperfusion era, β-blockers reduced cardiovascular mortality (IRR 0.87; 95% CI, 0.78-0.98), myocardial infarction (IRR 0.78; 95% CI, 0.62-0.97), and angina (IRR 0.88; 95% CI, 0.82-0.95), with no difference for other outcomes. In the reperfusion era, β-blockers reduced myocardial infarction (IRR 0.72; 95% CI, 0.62-0.83) (number needed to treat to benefit [NNTB] = 209) and angina (IRR 0.80; 95% CI, 0.65-0.98) (NNTB = 26) at the expense of increase in heart failure (IRR 1.10; 95% CI, 1.05-1.16) (number needed to treat to harm [NNTH] = 79), cardiogenic shock (IRR 1.29; 95% CI, 1.18-1.41) (NNTH = 90), and drug discontinuation (IRR 1.64; 95% CI, 1.55-1.73), with no benefit for other outcomes. Benefits for recurrent myocardial infarction and angina in the reperfusion era appeared to be short term (30 days).

CONCLUSIONS

In contemporary practice of treatment of myocardial infarction, β-blockers have no mortality benefit but reduce recurrent myocardial infarction and angina (short-term) at the expense of increase in heart failure, cardiogenic shock, and drug discontinuation. The guideline authors should reconsider the strength of recommendations for β-blockers post myocardial infarction.

How to read a systematic review and meta-analysis and apply the results to patient care: users' guides to the medical literature

Clinical decisions should be based on the totality of the best evidence and not the results of individual studies. When clinicians apply the results of a systematic review or meta-analysis to patient care, they should start by evaluating the credibility of the methods of the systematic review, ie, the extent to which these methods have likely protected against misleading results. Credibility depends on whether the review addressed a sensible clinical question; included an exhaustive literature search; demonstrated reproducibility of the selection and assessment of studies; and presented results in a useful manner. For reviews that are sufficiently credible, clinicians must decide on the degree of confidence in the estimates that the evidence warrants (quality of evidence). Confidence depends on the risk of bias in the body of evidence; the precision and consistency of the results; whether the results directly apply to the patient of interest; and the likelihood of reporting bias. Shared decision making requires understanding of the estimates of magnitude of beneficial and harmful effects, and confidence in those estimates.

Cardiac biomarkers in the prediction of risk in the non-cardiac surgery setting

B-Type natriuretic peptides and troponin measurements have potential in predicting risk in patients undergoing non-cardiac surgery. Using the American Heart Association framework for the evaluation of novel biomarkers, we review the current evidence supporting the peri-operative use of these two biomarkers. In patients having major non-cardiac surgery who are risk stratified using clinical risk scores, the measurement of natriuretic peptides and troponin, both before and after surgery, significantly improves risk stratification. However, only pre- and postoperative natriuretic peptide measurement and postoperative troponin measurement have shown clinical utility. It is now important for trials to be conducted to determine whether integrating pre- and postoperative natriuretic peptide and postoperative troponin measurement into clinical practice is able to improve clinical outcomes in patients undergoing non-cardiac surgery.

Kidney function after off-pump or on-pump coronary artery bypass graft surgery: a randomized clinical trial

IMPORTANCE

Most acute kidney injury observed in the hospital is defined by sudden mild or moderate increases in the serum creatinine concentration, which may persist for several days. Such acute kidney injury is associated with lower long-term kidney function. However, it has not been demonstrated that an intervention that reduces the risk of such acute kidney injury better preserves long-term kidney function.

OBJECTIVES

To characterize the risk of acute kidney injury with an intervention in a randomized clinical trial and to determine if there is a difference between the 2 treatment groups in kidney function 1 year later.

DESIGN, SETTING, AND PARTICIPANTS

The Coronary Artery Bypass Grafting Surgery Off- or On-pump Revascularisation Study (CORONARY) enrolled 4752 patients undergoing first isolated coronary artery bypass graft (CABG) surgery at 79 sites in 19 countries. Patients were randomized to receive CABG surgery either with a beating-heart technique (off-pump) or with cardiopulmonary bypass (on-pump). From January 2010 to November 2011, 2932 patients (from 63 sites in 16 countries) from CORONARY were enrolled into a kidney function substudy to record serum creatinine concentrations during the postoperative period and at 1 year. The last 1-year serum creatinine concentration was recorded on January 18, 2013.

MAIN OUTCOMES AND MEASURES

Acute kidney injury within 30 days of surgery (≥50% increase in serum creatinine concentration from prerandomization concentration) and loss of kidney function at 1 year (≥20% loss in estimated glomerular filtration rate from prerandomization level).

RESULTS

Off-pump (n = 1472) vs on-pump (n = 1460) CABG surgery reduced the risk of acute kidney injury (17.5% vs 20.8%, respectively; relative risk, 0.83 [95% CI, 0.72-0.97], P = .01); however, there was no significant difference between the 2 groups in the loss of kidney function at 1 year (17.1% vs 15.3%, respectively; relative risk, 1.10 [95% CI, 0.95-1.29], P = .23). Results were consistent with multiple alternate continuous and categorical definitions of acute kidney injury or kidney function loss, and in the subgroup with baseline chronic kidney disease.

CONCLUSIONS AND RELEVANCE

Use of off-pump compared with on-pump CABG surgery reduced the risk of postoperative acute kidney injury, without evidence of better preserved kidney function with off-pump CABG surgery at 1 year. In this setting, an intervention that reduced the risk of mild to moderate acute kidney injury did not alter longer-term kidney function.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00463294.

Aspirin in patients undergoing noncardiac surgery

BACKGROUND

There is substantial variability in the perioperative administration of aspirin in patients undergoing noncardiac surgery, both among patients who are already on an aspirin regimen and among those who are not.

METHODS

Using a 2-by-2 factorial trial design, we randomly assigned 10,010 patients who were preparing to undergo noncardiac surgery and were at risk for vascular complications to receive aspirin or placebo and clonidine or placebo. The results of the aspirin trial are reported here. The patients were stratified according to whether they had not been taking aspirin before the study (initiation stratum, with 5628 patients) or they were already on an aspirin regimen (continuation stratum, with 4382 patients). Patients started taking aspirin (at a dose of 200 mg) or placebo just before surgery and continued it daily (at a dose of 100 mg) for 30 days in the initiation stratum and for 7 days in the continuation stratum, after which patients resumed their regular aspirin regimen. The primary outcome was a composite of death or nonfatal myocardial infarction at 30 days.

RESULTS

The primary outcome occurred in 351 of 4998 patients (7.0%) in the aspirin group and in 355 of 5012 patients (7.1%) in the placebo group (hazard ratio in the aspirin group, 0.99; 95% confidence interval [CI], 0.86 to 1.15; P=0.92). Major bleeding was more common in the aspirin group than in the placebo group (230 patients [4.6%] vs. 188 patients [3.8%]; hazard ratio, 1.23; 95% CI, 1.01, to 1.49; P=0.04). The primary and secondary outcome results were similar in the two aspirin strata.

CONCLUSIONS

Administration of aspirin before surgery and throughout the early postsurgical period had no significant effect on the rate of a composite of death or nonfatal myocardial infarction but increased the risk of major bleeding. (Funded by the Canadian Institutes of Health Research and others; POISE-2 ClinicalTrials.gov number, NCT01082874.).

Clonidine in patients undergoing noncardiac surgery

BACKGROUND

Marked activation of the sympathetic nervous system occurs during and after noncardiac surgery. Low-dose clonidine, which blunts central sympathetic outflow, may prevent perioperative myocardial infarction and death without inducing hemodynamic instability.

METHODS

We performed a blinded, randomized trial with a 2-by-2 factorial design to allow separate evaluation of low-dose clonidine versus placebo and low-dose aspirin versus placebo in patients with, or at risk for, atherosclerotic disease who were undergoing noncardiac surgery. A total of 10,010 patients at 135 centers in 23 countries were enrolled. For the comparison of clonidine with placebo, patients were randomly assigned to receive clonidine (0.2 mg per day) or placebo just before surgery, with the study drug continued until 72 hours after surgery. The primary outcome was a composite of death or nonfatal myocardial infarction at 30 days.

RESULTS

Clonidine, as compared with placebo, did not reduce the number of primary-outcome events (367 and 339, respectively; hazard ratio with clonidine, 1.08; 95% confidence interval [CI], 0.93 to 1.26; P=0.29). Myocardial infarction occurred in 329 patients (6.6%) assigned to clonidine and in 295 patients (5.9%) assigned to placebo (hazard ratio, 1.11; 95% CI, 0.95 to 1.30; P=0.18). Significantly more patients in the clonidine group than in the placebo group had clinically important hypotension (2385 patients [47.6%] vs. 1854 patients [37.1%]; hazard ratio 1.32; 95% CI, 1.24 to 1.40; P<0.001). Clonidine, as compared with placebo, was associated with an increased rate of nonfatal cardiac arrest (0.3% [16 patients] vs. 0.1% [5 patients]; hazard ratio, 3.20; 95% CI, 1.17 to 8.73; P=0.02).

CONCLUSIONS

Administration of low-dose clonidine in patients undergoing noncardiac surgery did not reduce the rate of the composite outcome of death or nonfatal myocardial infarction; it did, however, increase the risk of clinically important hypotension and nonfatal cardiac arrest. (Funded by the Canadian Institutes of Health Research and others; POISE-2 ClinicalTrials.gov number, NCT01082874.).

Steroids In caRdiac Surgery (SIRS) trial: acute kidney injury substudy protocol of an international randomised controlled trial

INTRODUCTION

Steroids In caRdiac Surgery trial (SIRS) is a large international randomised controlled trial of methylprednisolone or placebo in patients undergoing cardiac surgery with the use of a cardiopulmonary bypass pump. At the time of surgery, compared with placebo, methylprednisolone divided into two intravenous doses of 250 mg each may reduce the risk of postoperative acute kidney injury (AKI).

METHODS AND ANALYSIS

With respect to the study schedule, over 7000 substudy eligible patients from 81 centres in 18 countries were randomised in December 2013. The authors will use a logistic regression to estimate the adjusted OR of methylprednisolone versus placebo on the primary outcome of AKI in the 14 days following surgery (a postoperative increase in serum creatinine of ≥50%, or ≥26.5 μmol/L, from the preoperative value). The stage of AKI will also be considered, as will the outcome of AKI in those with and without preoperative chronic kidney disease. After receipt of grant funding, the authors began to record additional perioperative serum creatinine measurements in consecutive patients enrolled at substudy participating centres, and patients were invited to enroll in a 6-month serum creatinine collection. In these trial subpopulations, the authors will consider the outcome of AKI defined in alternate ways, and the outcome of a 6-month change in kidney function from the preoperative value.

ETHICS AND DISSEMINATION

The authors were competitively awarded a grant from the Canadian Institutes of Health Research for this SIRS AKI substudy. Ethics approval was obtained for additional serum creatinine recordings in consecutive patients enrolled at participating centres. The additional kidney data collection first began for patients enrolled after 1 March 2012. In patients who provided consent, the last 6-month kidney outcome data will be collected in 2014. The results will be reported no later than 2015.

CLINICAL TRIAL REGISTRATION

Number NCT00427388.

Aspirin and clonidine in non-cardiac surgery: acute kidney injury substudy protocol of the Perioperative Ischaemic Evaluation (POISE) 2 randomised controlled trial

INTRODUCTION

Perioperative Ischaemic Evaluation-2 (POISE-2) is an international 2×2 factorial randomised controlled trial of low-dose aspirin versus placebo and low-dose clonidine versus placebo in patients who undergo non-cardiac surgery. Perioperative aspirin (and possibly clonidine) may reduce the risk of postoperative acute kidney injury (AKI).

METHODS AND ANALYSIS

After receipt of grant funding, serial postoperative serum creatinine measurements began to be recorded in consecutive patients enrolled at substudy participating centres. With respect to the study schedule, the last of over 6500 substudy patients from 82 centres in 21 countries were randomised in December 2013. The authors will use logistic regression to estimate the adjusted OR of AKI following surgery (compared with the preoperative serum creatinine value, a postoperative increase ≥26.5 μmol/L in the 2 days following surgery or an increase of ≥50% in the 7 days following surgery) comparing each intervention to placebo, and will report the adjusted relative risk reduction. Alternate definitions of AKI will also be considered, as will the outcome of AKI in subgroups defined by the presence of preoperative chronic kidney disease and preoperative chronic aspirin use. At the time of randomisation, a subpopulation agreed to a single measurement of serum creatinine between 3 and 12 months after surgery, and the authors will examine intervention effects on this outcome.

ETHICS AND DISSEMINATION

The authors were competitively awarded a grant from the Canadian Institutes of Health Research for this POISE-2 AKI substudy. Ethics approval was obtained for additional kidney data collection in consecutive patients enrolled at participating centres, which first began for patients enrolled after January 2011. In patients who provided consent, the remaining longer term serum creatinine data will be collected throughout 2014. The results of this study will be reported no later than 2015.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01082874.

Postoperative B-type natriuretic peptide for prediction of major cardiac events in patients undergoing noncardiac surgery: systematic review and individual patient meta-analysis

BACKGROUND

It is unclear whether postoperative B-type natriuretic peptides (i.e., BNP and N-terminal proBNP) can predict cardiovascular complications in noncardiac surgery.

METHODS

The authors undertook a systematic review and individual patient data meta-analysis to determine whether postoperative BNPs predict postoperative cardiovascular complications at 30 and 180 days or more.

RESULTS

The authors identified 18 eligible studies (n = 2,051). For the primary outcome of 30-day mortality or nonfatal myocardial infarction, BNP of 245 pg/ml had an area under the curve of 0.71 (95% CI, 0.64-0.78), and N-terminal proBNP of 718 pg/ml had an area under the curve of 0.80 (95% CI, 0.77-0.84). These thresholds independently predicted 30-day mortality or nonfatal myocardial infarction (adjusted odds ratio [AOR] 4.5; 95% CI, 2.74-7.4; P < 0.001), mortality (AOR, 4.2; 95% CI, 2.29-7.69; P < 0.001), cardiac mortality (AOR, 9.4; 95% CI, 0.32-254.34; P < 0.001), and cardiac failure (AOR, 18.5; 95% CI, 4.55-75.29; P < 0.001). For greater than or equal to 180-day outcomes, natriuretic peptides independently predicted mortality or nonfatal myocardial infarction (AOR, 3.3; 95% CI, 2.58-4.3; P < 0.001), mortality (AOR, 2.2; 95% CI, 1.67-86; P < 0.001), cardiac mortality (AOR, 2.1; 95% CI, 0.05-1,385.17; P < 0.001), and cardiac failure (AOR, 3.5; 95% CI, 1.0-9.34; P = 0.022). Patients with BNP values of 0-250, greater than 250-400, and greater than 400 pg/ml suffered the primary outcome at a rate of 6.6, 15.7, and 29.5%, respectively. Patients with N-terminal proBNP values of 0-300, greater than 300-900, and greater than 900 pg/ml suffered the primary outcome at a rate of 1.8, 8.7, and 27%, respectively.

CONCLUSIONS

Increased postoperative BNPs are independently associated with adverse cardiac events after noncardiac surgery.

The prognostic value of pre-operative and post-operative B-type natriuretic peptides in patients undergoing noncardiac surgery: B-type natriuretic peptide and N-terminal fragment of pro-B-type natriuretic peptide: a systematic review and individual patient data meta-analysis

OBJECTIVES

The objective of this study was to determine whether measuring post-operative B-type natriuretic peptides (NPs) (i.e., B-type natriuretic peptide [BNP] and N-terminal fragment of proBNP [NT-proBNP]) enhances risk stratification in adult patients undergoing noncardiac surgery, in whom a pre-operative NP has been measured.

BACKGROUND

Pre-operative NP concentrations are powerful independent predictors of perioperative cardiovascular complications, but recent studies have reported that elevated post-operative NP concentrations are independently associated with these complications. It is not clear whether there is value in measuring post-operative NP when a pre-operative measurement has been done.

METHODS

We conducted a systematic review and individual patient data meta-analysis to determine whether the addition of post-operative NP levels enhanced the prediction of the composite of death and nonfatal myocardial infarction at 30 and ≥180 days after surgery.

RESULTS

Eighteen eligible studies provided individual patient data (n = 2,179). Adding post-operative NP to a risk prediction model containing pre-operative NP improved model fit and risk classification at both 30 days (corrected quasi-likelihood under the independence model criterion: 1,280 to 1,204; net reclassification index: 20%; p < 0.001) and ≥180 days (corrected quasi-likelihood under the independence model criterion: 1,320 to 1,300; net reclassification index: 11%; p = 0.003). Elevated post-operative NP was the strongest independent predictor of the primary outcome at 30 days (odds ratio: 3.7; 95% confidence interval: 2.2 to 6.2; p < 0.001) and ≥180 days (odds ratio: 2.2; 95% confidence interval: 1.9 to 2.7; p < 0.001) after surgery.

CONCLUSIONS

Additional post-operative NP measurement enhanced risk stratification for the composite outcomes of death or nonfatal myocardial infarction at 30 days and ≥180 days after noncardiac surgery compared with a pre-operative NP measurement alone.

The association between perioperative hemoglobin and acute kidney injury in patients having noncardiac surgery

BACKGROUND

Acute kidney injury (AKI) is a common complication of noncardiac surgery and is associated with excess morbidity and mortality. Perioperative hemoglobin concentrations are strongly associated with surgical mortality, but little is known about their relationship with AKI. We studied hemoglobin concentration before and 24 hours after surgery and its association with AKI.

METHODS

We performed a single-center observational cohort study using clinical and administrative data from the Cleveland Clinic, Cleveland, OH. In patients with normal preoperative renal function, we examined the association between the outcome of AKI and the exposures of preoperative hemoglobin concentration and decrements in hemoglobin concentration in the first 24 hours after surgery using logistic regression and controlling for important confounding variables.

RESULTS

We included 27,381 patients who had 33,330 noncardiac surgeries. AKI developed in 2478 (7.4%) surgeries. Preoperative hemoglobin concentrations were <12.0 g/dL in 9566 (29%) patients. Hemoglobin concentrations decreased by >4.0 g/dL in 10,808 (32%) patients. Compared with patients with a preoperative hemoglobin >12.0 g/dL, the adjusted odds ratio (OR) for AKI was 2.01 (95% confidence interval [CI], 1.8-2.3) for those with a preoperative hemoglobin between 10.1 and 12.0 g/dL and was 3.7 (95% CI, 2.6-5.4) for those with a preoperative hemoglobin <8.0 g/dL. Compared with patients who did not have a decrease in postoperative hemoglobin, a decrement of 1.1 to 2.0 g/dL was associated with an adjusted OR of 1.51 (95% CI, 1.15-1.98), and a decrement of >4.0 g/dL with an OR of 4.7 (95% CI, 3.6-6.2) for AKI.

CONCLUSIONS

Low preoperative and early postoperative decrements in hemoglobin concentrations are strongly associated with postoperative AKI in a graded manner. Given the frequency of low perioperative hemoglobin and decreases in hemoglobin concentration, research is needed to determine whether there are safe treatment strategies to mitigate the risk of AKI.

Impact of tuberculosis on mortality among HIV-infected patients receiving antiretroviral therapy in Uganda: a prospective cohort analysis

Background

Tuberculosis (TB) disease affects survival among HIV co-infected patients on antiretroviral therapy (ART). Yet, the magnitude of TB disease on mortality is poorly understood.

Methods

Using a prospective cohort of 22,477 adult patients who initiated ART between August 2000 and June 2009 in Uganda, we assessed the effect of active pulmonary TB disease at the initiation of ART on all-cause mortality using a Cox proportional hazards model. Propensity score (PS) matching was used to control for potential confounding. Stratification and covariate adjustment for PS and not PS-based multivariable Cox models were also performed.

Results

A total of 1,609 (7.52%) patients had active pulmonary TB at the start of ART. TB patients had higher proportions of being male, suffering from AIDS-defining illnesses, having World Health Organization (WHO) disease stage III or IV, and having lower CD4 cell counts at baseline (p < 0.001). The percentages of death during follow-up were 10.47% and 6.38% for patients with and without TB, respectively. The hazard ratio (HR) for mortality comparing TB to non-TB patients using 1,686 PS-matched pairs was 1.37 (95% confidence interval [CI]: 1.08 – 1.75), less marked than the crude estimate (HR = 1.74, 95% CI: 1.49 – 2.04). The other PS-based methods and not PS-based multivariable Cox model produced similar results.

Conclusions

After controlling for important confounding variables, HIV patients who had TB at the initiation of ART in Uganda had an approximate 37% increased hazard of overall mortality relative to non-TB patients.

Rationale and design of the Primary pREvention strategies at the community level to Promote Adherence of treatments to pREvent cardiovascular diseases trial number (CTRI/2012/09/002981)

INTRODUCTION

Cardiovascular diseases (CVDs) are a leading cause of morbidity and mortality in low-income countries including India. There is a need for effective, low-cost methods to prevent CVDs in rural India. One strategy is to identify and implement interventions at high-risk individuals using community health workers (CHWs). There is a paucity of CHW-based CVD intervention trials from low-income countries.

METHODS

We designed a multicenter, household-level, cluster-randomized trial with 1:1 allocation to intervention and control arms. The CHWs undertook a door-to-door survey and screened 5,699 households in 28 villages from 3 rural regions in India to identify at-risk households. The households were defined as those with ≥1 individual aged ≥35 years and at moderate or high risk for CVD based on the non-laboratory-based National Health and Nutrition Examination Survey score. All at-risk individuals were invited to attend a physician-led village clinic that provided a CVD risk reduction prescription and education about target risk factor levels for CVD control. All households in which at least 1 member at moderate to high risk for CVD had received a risk reduction prescription were eligible for randomization. Households randomized to the CHW-based intervention will receive 1 household visit by a CHW every 2 months, for 12 months. During these visits, CHWs will measure blood pressure, ascertain and reinforce adherence to prescribed therapies, and modify therapy to meet targets. Households randomized to the control arm do not receive CHW visits. At 12 months after randomization, we will evaluate 2 primary outcomes of systolic blood pressure and adherence to antihypertensive drugs and secondary outcomes of INTERHEART risk score, body mass index, and waist-to-hip ratios. At 18 to 24 months after randomization and 6 to 12 months after the last intervention, we will record these outcomes to evaluate sustainability of intervention.

RESULTS

Community health workers screened a total of 5,033 households that included 9,248 individuals and identified 2,571 households with 3,784 at-risk individuals. We randomized 2,438 households (1,219 to intervention and 1,219 to control groups).

CONCLUSION

Our large trial of CHWs in rural India will provide important information regarding a promising approach to primary prevention of CVDs.

Protocol understanding and anxiety in perioperative clinical trial patients approached for consent on the day of surgery

OBJECTIVE

To determine whether approaching patients for consent on the day of surgery impairs understanding or produces unacceptable anxiety compared with obtaining consent before the day of surgery.

PATIENTS AND METHODS

We assessed the effect of the timing of obtaining consent for a moderate- to high-risk factorial trial of clonidine and aspirin in patients having noncardiac surgery. Between February 1, 2011, and November 31, 2011, 2 study personnel used the same standardized script to recruit patients before the day of surgery or on the day of surgery. Patients eligible for the trial were preferentially approached to obtain consent before the day of surgery in the preoperative clinic. Patients who did not attend the preoperative clinic or could not be approached that day were approached for consent on the day of surgery. We evaluated anxiety before and after the trial was discussed, protocol knowledge, consent rates, and perceived obligation to participate. All comparisons were adjusted for differences in potentially confounding variables using inverse propensity score weighting.

RESULTS

Patients approached on the day of surgery compared with before the day of surgery had noninferior understanding of the comprehension score (adjusted mean difference, -0.19; 90% CI, -0.47 to 0.10; P<.001 for noninferiority) and a noninferior mean increase in the postapproach anxiety score (adjusted mean difference, 0.19; 90% CI, -0.29 to 0.68; P=.003 for noninferiority). Perceived obligation to participate was not greater on the day of surgery (adjusted mean difference, 0.09; 95% CI, -0.21 to 0.40; P=.57 for superiority); however, consent rates were significantly lower (31% vs 59%; odds ratio, 0.49; 90% CI, 0.33 to 0.72; P=.46 for noninferiority).

CONCLUSION

Approaching patients to obtain consent to participate in a perioperative interventional trial on the day of surgery does not compromise essential elements of the consent process.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01082874.

Effects of off-pump and on-pump coronary-artery bypass grafting at 1 year

BACKGROUND

Previously, we reported that there was no significant difference at 30 days in the rate of a primary composite outcome of death, myocardial infarction, stroke, or new renal failure requiring dialysis between patients who underwent coronary-artery bypass grafting (CABG) performed with a beating-heart technique (off-pump) and those who underwent CABG performed with cardiopulmonary bypass (on-pump). We now report results on quality of life and cognitive function and on clinical outcomes at 1 year.

METHODS

We enrolled 4752 patients with coronary artery disease who were scheduled to undergo CABG and randomly assigned them to undergo the procedure off-pump or on-pump. Patients were enrolled at 79 centers in 19 countries. We assessed quality of life and cognitive function at discharge, at 30 days, and at 1 year and clinical outcomes at 1 year.

RESULTS

At 1 year, there was no significant difference in the rate of the primary composite outcome between off-pump and on-pump CABG (12.1% and 13.3%, respectively; hazard ratio with off-pump CABG, 0.91; 95% confidence interval [CI], 0.77 to 1.07; P=0.24). The rate of the primary outcome was also similar in the two groups in the period between 31 days and 1 year (hazard ratio, 0.79; 95% CI, 0.55 to 1.13; P=0.19). The rate of repeat coronary revascularization at 1 year was 1.4% in the off-pump group and 0.8% in the on-pump group (hazard ratio, 1.66; 95% CI, 0.95 to 2.89; P=0.07). There were no significant differences between the two groups at 1 year in measures of quality of life or neurocognitive function.

CONCLUSIONS

At 1 year after CABG, there was no significant difference between off-pump and on-pump CABG with respect to the primary composite outcome, the rate of repeat coronary revascularization, quality of life, or neurocognitive function. (Funded by the Canadian Institutes of Health Research; CORONARY ClinicalTrials.gov number, NCT00463294.).

Abstract TMP9: The Neurovision Pilot Study: Non-cardiac Surgery Carries A Significant Risk Of Acute Covert Stroke

Introduction: 200 million patients worldwide undergo noncardiac surgery every year. Overt stroke is a serious complication of noncardiac surgery with significant impact on duration and quality of life. In the non-surgical population, covert stroke is 10 times more common then overt stroke and is associated with an increased risk of dementia and cognitive decline. The epidemiology of covert stroke after noncardiac surgery is not well characterized.

Study Objectives: We undertook a pilot study to determine the incidence of covert stroke after noncardiac surgery.

Methods: This was a prospective, international cohort study. Eligible patients were 65 years or older, and were admitted to hospital for at least one night after noncardiac surgery. A sampling strategy was employed to ensure a representative surgical population. Study personnel recorded clinical characteristics and the incidence of perioperative adverse events. We also assessed neurocognitive function, physical function and quality of life before surgery and 30 days after surgery. Patients underwent a brain magnetic resonance imaging (MRI) study between postoperative days 3 and 10. Fluid attenuated inversion recovery, gradient echo, T2 and diffusion-weighted imaging MRI sequences were obtained.

Results: A total of 70 patients from three centres were enrolled in this study. The incidence of covert stroke was 11.4% (8/70 patients, 95% CI 5.9% to 21.0%). The single overt stroke was diagnosed after the research MRI study demonstrated findings of an acute stroke. All three centres experienced a similar prevalence of covert stroke (range 8.0% to 15.0%), and covert stroke was found in patients undergoing general (4/16), orthopedic (3/36), and urological/gynecological surgery (2/8).

Conclusions: There is a significant risk of covert stroke after all types of noncardiac surgery. Given that globally 200 million adults undergoing major noncardiac surgery every year, postoperative covert stroke may be responsible for a significant proportion of small vessel cerebral ischemic disease in the overall population. A large study is needed to characterize the impact of postoperative covert stroke on clinically meaningful outcomes.

Central statistical monitoring: detecting fraud in clinical trials

BACKGROUND

Central statistical monitoring in multicenter trials could allow trialists to identify centers with problematic data or conduct and intervene while the trial is still ongoing. Currently, there are few published models that can be used for this purpose.

PURPOSE

To develop and validate a series of risk scores to identify fabricated data within a multicenter trial, to be used in central statistical monitoring.

METHODS

We used a database from a multicenter trial in which data from 9 of 109 centers were documented to be fabricated. These data were used to build a series of risk scores to predict fraud at centers. All analyses were performed at the level of the center. Exploratory factor analysis was used to select from 52 possible predictors, chosen from a variety of previously published methods. The final models were selected from a total of 18 independent predictors, based on the factors identified. These models were converted to risk scores for each center.

RESULTS

Five different risk scores were identified, and each had the ability to discriminate well between centers with and without fabricated data (area under the curve values ranged from 0.90 to 0.95). True- and false-positive rates are presented for each risk score to arrive at a recommended cutoff of seven or above (high risk score). We validated these risk scores, using an independent multicenter trial database that contained no data fabrication and found the occurrence of false-positive high scores to be low and comparable to the model-building data set.

LIMITATIONS

These risk score have been validated only for their false-positive rate and require validation within another trial that contains centers that have fabricated data. Validation in noncardiovascular trials is also required to gage the usefulness of these risk scores in central statistical monitoring.

CONCLUSIONS

With further validation, these risk scores could become part of a series of tools that provide evidence-based central statistical monitoring, which in turn can improve the efficiency of trials, and minimize the need for more expensive on-site monitoring.

Increased cardiovascular risk after pre-eclampsia in women with dysglycaemia

AIMS

Compared with women with uncomplicated pregnancies, women with a history of pre-eclampsia have two to five times the risk of cardiovascular disease. It is not known whether this risk is related to albuminuria, a known cardiovascular risk factor that is part of the definition of pre-eclampsia and that often persists after delivery. Our objective was to determine if the high risk of cardiovascular disease in women with pre-eclampsia is accounted for by known cardiovascular risk factors including albuminuria.

METHODS

We performed a cross-sectional analysis of 4080 dysglycaemic women enrolled in a large randomized controlled trial who provided an obstetric history and had at least one delivery. Blood pressure, height, weight, waist circumference and hip circumference were measured. An oral glucose tolerance test, lipids, an electrocardiogram and an albumin/creatinine ratio from a first morning urine sample were obtained.

RESULTS

There were 3613 women with no history of pre-eclampsia during their pregnancies, 108 with severe pre-eclampsia and 359 with non-severe pre-eclampsia. Women with a history of severe pre-eclampsia had higher rates of previous cardiovascular disease than women with non-severe pre-eclampsia or women without pre-eclampsia (87, 72 and 72%, P = 0.0019). The high risk of previous cardiovascular disease in women with a history of severe pre-eclampsia (odds ratio 2.67, 95% CI 1.52-4.70) persisted after adjustment for albuminuria (odds ratio 2.74, 95% CI 1.55-4.83) and also after adjusting for other covariates including albuminuria (odds ratio 3.03, 95% CI 1.69-5.44).

CONCLUSION

Even after accounting for cardiovascular risk factors including albuminuria, a history of severe pre-eclampsia is independently associated with a threefold higher risk of cardiovascular disease.

A meta-analysis of randomized controlled trials comparing percutaneous coronary intervention with medical therapy in stable angina pectoris

There continues to remain uncertainty regarding the effect of percutaneous coronary intervention (PCI) vs medical therapy in patients with stable angina. We therefore performed a systematic review and study-level meta-analysis of randomized controlled trials of patients with stable angina comparing PCI vs medical therapy for each of the following individual outcomes: all-cause mortality, cardiovascular (CV) mortality, myocardial infarction (MI), and angina relief. We used 8 strategies to identify eligible trials including bibliographic database searches of MEDLINE, PubMed, EMBASE, and the Cochrane Controlled Trials Registry until November 2011. Two independent reviewers undertook decisions about study eligibility and data abstraction. Data were pooled using a random effects model. Ten prospective randomized controlled trials fulfilled our eligibility criteria and they included a total of 6752 patients. We did not detect differences between PCI vs medical therapy for all-cause mortality (663 events; relative risk [RR], 0.97 [confidence interval (CI), 0.84-1.12]; I(2) = 0%), CV mortality (214 events; RR, 0.91 [CI, 0.70-1.17]; I(2) = 0%), MI (472 events; RR, 1.09 [CI, 0.92-1.29]; I(2) = 0%), or angina relief at the end of follow-up (2016 events; RR, 1.10 [CI, 0.97-1.26]; I(2)=85%). PCI was not associated with reductions in all-cause or CV mortality, MI, or angina relief. Considering the cost implication and the lack of clear clinical benefit, these findings continue to support existing clinical practice guidelines that medical therapy be considered the most appropriate initial clinical management for patients with stable angina.

Revisiting sample size: are big trials the answer?

The superiority of the evidence generated in randomized controlled trials over observational data is not only conditional to randomization. Randomized controlled trials require proper design and implementation to provide a reliable effect estimate. Adequate random sequence generation, allocation implementation, analyses based on the intention-to-treat principle, and sufficient power are crucial to the quality of a randomized controlled trial. Power, or the probability of the trial to detect a difference when a real difference between treatments exists, strongly depends on sample size. The quality of orthopaedic randomized controlled trials is frequently threatened by a limited sample size. This paper reviews basic concepts and pitfalls in sample-size estimation and focuses on the importance of large trials in the generation of valid evidence.

Emerging designs in orthopaedics: expertise-based randomized controlled trials

In this article, we discuss the limitations of conventional randomized controlled trials (RCTs) in the surgical field. Surgeons are often believers in certain surgical techniques and therefore can be reluctant to learn new interventions. In expertise-based trials, the patients are randomized to surgeons with expertise in the intervention under investigation. In conventional RCTs, patients are randomized to an intervention, and surgeons will perform this intervention regardless of whether this is the surgery they typically undertake. Conventional randomization may lead to surgery performed by a less experienced or less motivated surgeon, resulting in differential expertise bias. Expertise-based trials can overcome these limitations if potential pitfalls are taken into account.

Association between postoperative troponin levels and 30-day mortality among patients undergoing noncardiac surgery

CONTEXT

Of the 200 million adults worldwide who undergo noncardiac surgery each year, more than 1 million will die within 30 days.

OBJECTIVE

To determine the relationship between the peak fourth-generation troponin T (TnT) measurement in the first 3 days after noncardiac surgery and 30-day mortality.

DESIGN, SETTING, AND PARTICIPANTS

A prospective, international cohort study that enrolled patients from August 6, 2007, to January 11, 2011. Eligible patients were aged 45 years and older and required at least an overnight hospital admission after having noncardiac surgery.

MAIN OUTCOME MEASURES

Patients' TnT levels were measured 6 to 12 hours after surgery and on days 1, 2, and 3 after surgery. We undertook Cox regression analysis in which the dependent variable was mortality until 30 days after surgery, and the independent variables included 24 preoperative variables. We repeated this analysis, adding the peak TnT measurement during the first 3 postoperative days as an independent variable and used a minimum P value approach to determine if there were TnT thresholds that independently altered patients' risk of death.

RESULTS

A total of 15,133 patients were included in this study. The 30-day mortality rate was 1.9% (95% CI, 1.7%-2.1%). Multivariable analysis demonstrated that peak TnT values of at least 0.02 ng/mL, occurring in 11.6% of patients, were associated with higher 30-day mortality compared with the reference group (peak TnT ≤ 0.01 ng/mL): peak TnT of 0.02 ng/mL (adjusted hazard ratio [aHR], 2.41; 95% CI, 1.33-3.77); 0.03 to 0.29 ng/mL (aHR, 5.00; 95% CI, 3.72-6.76); and 0.30 ng/mL or greater (aHR, 10.48; 95% CI, 6.25-16.62). Patients with a peak TnT value of 0.01 ng/mL or less, 0.02, 0.03-0.29, and 0.30 or greater had 30-day mortality rates of 1.0%, 4.0%, 9.3%, and 16.9%, respectively. Peak TnT measurement added incremental prognostic value to discriminate those likely to die within 30 days for the model with peak TnT measurement vs without (C index = 0.85 vs 0.81; difference, 0.4; 95% CI, 0.2-0.5; P < .001 for difference between C index values). The net reclassification improvement with TnT was 25.0% (P < .001).

CONCLUSION

Among patients undergoing noncardiac surgery, the peak postoperative TnT measurement during the first 3 days after surgery was significantly associated with 30-day mortality.

Assessment and implication of prognostic imbalance in randomized controlled trials with a binary outcome--a simulation study

BACKGROUND

Chance imbalance in baseline prognosis of a randomized controlled trial can lead to over or underestimation of treatment effects, particularly in trials with small sample sizes. Our study aimed to (1) evaluate the probability of imbalance in a binary prognostic factor (PF) between two treatment arms, (2) investigate the impact of prognostic imbalance on the estimation of a treatment effect, and (3) examine the effect of sample size (n) in relation to the first two objectives.

METHODS

We simulated data from parallel-group trials evaluating a binary outcome by varying the risk of the outcome, effect of the treatment, power and prevalence of the PF, and n. Logistic regression models with and without adjustment for the PF were compared in terms of bias, standard error, coverage of confidence interval and statistical power.

RESULTS

For a PF with a prevalence of 0.5, the probability of a difference in the frequency of the PF≥5% reaches 0.42 with 125/arm. Ignoring a strong PF (relative risk = 5) leads to underestimating the strength of a moderate treatment effect, and the underestimate is independent of n when n is >50/arm. Adjusting for such PF increases statistical power. If the PF is weak (RR = 2), adjustment makes little difference in statistical inference. Conditional on a 5% imbalance of a powerful PF, adjustment reduces the likelihood of large bias. If an absolute measure of imbalance ≥5% is deemed important, including 1000 patients/arm provides sufficient protection against such an imbalance. Two thousand patients/arm may provide an adequate control against large random deviations in treatment effect estimation in the presence of a powerful PF.

CONCLUSIONS

The probability of prognostic imbalance in small trials can be substantial. Covariate adjustment improves estimation accuracy and statistical power, and hence should be performed when strong PFs are observed.

Off-pump or on-pump coronary-artery bypass grafting at 30 days

BACKGROUND

The relative benefits and risks of performing coronary-artery bypass grafting (CABG) with a beating-heart technique (off-pump CABG), as compared with cardiopulmonary bypass (on-pump CABG), are not clearly established.

METHODS

At 79 centers in 19 countries, we randomly assigned 4752 patients in whom CABG was planned to undergo the procedure off-pump or on-pump. The first coprimary outcome was a composite of death, nonfatal stroke, nonfatal myocardial infarction, or new renal failure requiring dialysis at 30 days after randomization.

RESULTS

There was no significant difference in the rate of the primary composite outcome between off-pump and on-pump CABG (9.8% vs. 10.3%; hazard ratio for the off-pump group, 0.95; 95% confidence interval [CI], 0.79 to 1.14; P=0.59) or in any of its individual components. The use of off-pump CABG, as compared with on-pump CABG, significantly reduced the rates of blood-product transfusion (50.7% vs. 63.3%; relative risk, 0.80; 95% CI, 0.75 to 0.85; P<0.001), reoperation for perioperative bleeding (1.4% vs. 2.4%; relative risk, 0.61; 95% CI, 0.40 to 0.93; P=0.02), acute kidney injury (28.0% vs. 32.1%; relative risk, 0.87; 95% CI, 0.80 to 0.96; P=0.01), and respiratory complications (5.9% vs. 7.5%; relative risk, 0.79; 95% CI, 0.63 to 0.98; P=0.03) but increased the rate of early repeat revascularizations (0.7% vs. 0.2%; hazard ratio, 4.01; 95% CI, 1.34 to 12.0; P=0.01).

CONCLUSIONS

There was no significant difference between off-pump and on-pump CABG with respect to the 30-day rate of death, myocardial infarction, stroke, or renal failure requiring dialysis. The use of off-pump CABG resulted in reduced rates of transfusion, reoperation for perioperative bleeding, respiratory complications, and acute kidney injury but also resulted in an increased risk of early revascularization. (Funded by the Canadian Institutes of Health Research; CORONARY ClinicalTrials.gov number, NCT00463294.).