Tim Ramsay

Identifying unprovoked thromboembolism patients at low risk for recurrence who can discontinue anticoagulant therapy

Background: Whether to continue oral anticoagulant therapy beyond 6 months after an “unprovoked” venous thromboembolism is controversial. We sought to determine clinical predictors to identify patients who are at low risk of recurrent venous thromboembolism who could safely discontinue oral anticoagulants. Methods: In a multicentre prospective cohort study, 646 participants with a first, unprovoked major venous thromboembolism were enrolled over a 4-year period. Of these, 600 participants completed a mean 18-month follow-up in September 2006. We collected data for 69 potential predictors of recurrent venous thromboembolism while patients were taking oral anticoagulation therapy (5–7 months after initiation). During follow-up after discontinuing oral anticoagulation therapy, all episodes of suspected recurrent venous thromboembolism were independently adjudicated. We performed a multivariable analysis of predictor variables (p < 0.10) with high interobserver reliability to derive a clinical decision rule. Results: We identified 91 confirmed episodes of recurrent venous thromboembolism during follow-up after discontinuing oral anticoagulation therapy (annual risk 9.3%, 95% CI 7.7%–11.3%). Men had a 13.7% (95% CI 10.8%–17.0%) annual risk. There was no combination of clinical predictors that satisfied our criteria for identifying a low-risk subgroup of men. Fifty-two percent of women had 0 or 1 of the following characteristics: hyperpigmentation, edema or redness of either leg; D-dimer ≥ 250 μg/L while taking warfarin; body mass index ≥ 30 kg/m2; or age ≥ 65 years. These women had an annual risk of 1.6% (95% CI 0.3%–4.6%). Women who had 2 or more of these findings had an annual risk of 14.1% (95% CI 10.9%–17.3%). Interpretation: Women with 0 or 1 risk factor may safely discontinue oral anticoagulant therapy after 6 months of therapy following a first unprovoked venous thromboembolism. This criterion does not apply to men. (http://Clinicaltrials.gov trial register number NCT00261014)

External Validation of a Measurement Tool to Assess Systematic Reviews (AMSTAR)

Background Thousands of systematic reviews have been conducted in all areas of health care. However, the methodological quality of these reviews is variable and should routinely be appraised. AMSTAR is a measurement tool to assess systematic reviews. Methodology AMSTAR was used to appraise 42 reviews focusing on therapies to treat gastro-esophageal reflux disease, peptic ulcer disease, and other acid-related diseases. Two assessors applied the AMSTAR to each review. Two other assessors, plus a clinician and/or methodologist applied a global assessment to each review independently. Conclusions The sample of 42 reviews covered a wide range of methodological quality. The overall scores on AMSTAR ranged from 0 to 10 (out of a maximum of 11) with a mean of 4.6 (95% CI: 3.7 to 5.6) and median 4.0 (range 2.0 to 6.0). The inter-observer agreement of the individual items ranged from moderate to almost perfect agreement. Nine items scored a kappa of >0.75 (95% CI: 0.55 to 0.96). The reliability of the total AMSTAR score was excellent: kappa 0.84 (95% CI: 0.67 to 1.00) and Pearsons R 0.96 (95% CI: 0.92 to 0.98). The overall scores for the global assessment ranged from 2 to 7 (out of a maximum score of 7) with a mean of 4.43 (95% CI: 3.6 to 5.3) and median 4.0 (range 2.25 to 5.75). The agreement was lower with a kappa of 0.63 (95% CI: 0.40 to 0.88). Construct validity was shown by AMSTAR convergence with the results of the global assessment: Pearsons R 0.72 (95% CI: 0.53 to 0.84). For the AMSTAR total score, the limits of agreement were −0.19±1.38. This translates to a minimum detectable difference between reviews of 0.64 ‘AMSTAR points’. Further validation of AMSTAR is needed to assess its validity, reliability and perceived utility by appraisers and end users of reviews across a broader range of systematic reviews.

Effectiveness of quality improvement strategies on the management of diabetes: a systematic review and meta-analysis

BACKGROUND The effectiveness of quality improvement (QI) strategies on diabetes care remains unclear. We aimed to assess the effects of QI strategies on glycated haemoglobin (HbA(1c)), vascular risk management, microvascular complication monitoring, and smoking cessation in patients with diabetes. METHODS We identified studies through Medline, the Cochrane Effective Practice and Organisation of Care database (from inception to July 2010), and references of included randomised clinical trials. We included trials assessing 11 predefined QI strategies or financial incentives targeting health systems, health-care professionals, or patients to improve management of adult outpatients with diabetes. Two reviewers independently abstracted data and appraised risk of bias. FINDINGS We reviewed 48 cluster randomised controlled trials, including 2538 clusters and 84,865 patients, and 94 patient randomised controlled trials, including 38,664 patients. In random effects meta-analysis, the QI strategies reduced HbA(1c) by a mean difference of 0·37% (95% CI 0·28-0·45; 120 trials), LDL cholesterol by 0·10 mmol/L (0·05-0.14; 47 trials), systolic blood pressure by 3·13 mm Hg (2·19-4·06, 65 trials), and diastolic blood pressure by 1·55 mm Hg (0·95-2·15, 61 trials) versus usual care. We noted larger effects when baseline concentrations were greater than 8·0% for HbA(1c), 2·59 mmol/L for LDL cholesterol, and 80 mm Hg for diastolic and 140 mm Hg for systolic blood pressure. The effectiveness of QI strategies varied depending on baseline HbA(1c) control. QI strategies increased the likelihood that patients received aspirin (11 trials; relative risk [RR] 1·33, 95% CI 1·21-1·45), antihypertensive drugs (ten trials; RR 1·17, 1·01-1·37), and screening for retinopathy (23 trials; RR 1·22, 1·13-1·32), renal function (14 trials; RR 128, 1·13-1·44), and foot abnormalities (22 trials; RR 1·27, 1·16-1·39). However, statin use (ten trials; RR 1·12, 0·99-1·28), hypertension control (18 trials; RR 1·01, 0·96-1·07), and smoking cessation (13 trials; RR 1·13, 0·99-1·29) were not significantly increased. INTERPRETATION Many trials of QI strategies showed improvements in diabetes care. Interventions targeting the system of chronic disease management along with patient-mediated QI strategies should be an important component of interventions aimed at improving diabetes management. Interventions solely targeting health-care professionals seem to be beneficial only if baseline HbA(1c) control is poor. FUNDING Ontario Ministry of Health and Long-term Care and the Alberta Heritage Foundation for Medical Research (now Alberta Innovates--Health Solutions).

Acute Effects of Ambient Particulate Matter on Mortality in Europe and North America : Results from the APHENA Study

Background The APHENA (Air Pollution and Health: A Combined European and North American Approach) study is a collaborative analysis of multicity time-series data on the effect of air pollution on population health, bringing together data from the European APHEA (Air Pollution and Health: A European Approach) and U.S. NMMAPS (National Morbidity, Mortality and Air Pollution Study) projects, along with Canadian data. Objectives The main objective of APHENA was to assess the coherence of the findings of the multicity studies carried out in Europe and North America, when analyzed with a common protocol, and to explore sources of possible heterogeneity. We present APHENA results on the effects of particulate matter (PM) ≤ 10 μm in aerodynamic diameter (PM10) on the daily number of deaths for all ages and for those < 75 and ≥ 75 years of age. We explored the impact of potential environmental and socioeconomic factors that may modify this association. Methods In the first stage of a two-stage analysis, we used Poisson regression models, with natural and penalized splines, to adjust for seasonality, with various degrees of freedom. In the second stage, we used meta-regression approaches to combine time-series results across cites and to assess effect modification by selected ecologic covariates. Results Air pollution risk estimates were relatively robust to different modeling approaches. Risk estimates from Europe and United States were similar, but those from Canada were substantially higher. The combined effect of PM10 on all-cause mortality across all ages for cities with daily air pollution data ranged from 0.2% to 0.6% for a 10-μg/m3 increase in ambient PM10 concentration. Effect modification by other pollutants and climatic variables differed in Europe and the United States. In both of these regions, a higher proportion of older people and higher unemployment were associated with increased air pollution risk. Conclusions Estimates of the increased mortality associated with PM air pollution based on the APHENA study were generally comparable with results of previous reports. Overall, risk estimates were similar in Europe and in the United States but higher in Canada. However, PM10 effect modification patterns were somewhat different in Europe and the United States.

Systematic Classification of Morbidity and Mortality After Thoracic Surgery

BACKGROUND Objective reporting of postoperative complications is the foundation of surgical quality assurance. We developed a system to identify both presence and severity of thoracic morbidity and mortality, and evaluated its feasibility and utility over the first two years of its implementation. METHODS The system was based on the Clavien-Dindo classification, in which the severity of a complication is proportional to the effort to treat it. Definitions were developed by peer review and questionnaire. All patients undergoing thoracic surgery (January 2008 to December 2009) were prospectively evaluated. RESULTS A total of 953 patients (mean age 61 years; range, 14 to 95) underwent thoracic surgery (total # cases 1260), of which 369 patients had at least one complication (29.3% procedures). Grades I and II include minor complications requiring no therapy or pharmacologic intervention only. Grades III and IV are major complications that require surgical intervention or life support. Grade V complications result in patient death. Grades I, II, III, and IV complications comprised 4.9%, 63.9%, 21.1%, and 7.8% of all complications; overall mortality rate (grade V) was 2.2%. The most common complications were prolonged air leak (18.8%) and atrial fibrillation (18.2%) after pulmonary resection, and atrial fibrillation (11.5%) after esophagectomy-gastrectomy. Prolonged air leak led to a major complication (13%), readmission (17%), or prolonged hospital stay (29%) to a greater extent than atrial fibrillation (3%, 2%, and 7%, respectively). CONCLUSIONS This standardized classification system for identifying presence and severity of thoracic surgical complications is feasible, facilitates objective comparison, identifies burden of illness of individual complications, and provides an effective method for continuous surgical quality assessment.

Continuous Multi-Parameter Heart Rate Variability Analysis Heralds Onset of Sepsis in Adults

Background Early diagnosis of sepsis enables timely resuscitation and antibiotics and prevents subsequent morbidity and mortality. Clinical approaches relying on point-in-time analysis of vital signs or lab values are often insensitive, non-specific and late diagnostic markers of sepsis. Exploring otherwise hidden information within intervals-in-time, heart rate variability (HRV) has been documented to be both altered in the presence of sepsis, and correlated with its severity. We hypothesized that by continuously tracking individual patient HRV over time in patients as they develop sepsis, we would demonstrate reduced HRV in association with the onset of sepsis. Methodology/Principal Findings We monitored heart rate continuously in adult bone marrow transplant (BMT) patients (n = 21) beginning a day before their BMT and continuing until recovery or withdrawal (12±4 days). We characterized HRV continuously over time with a panel of time, frequency, complexity, and scale-invariant domain techniques. We defined baseline HRV as mean variability for the first 24 h of monitoring and studied individual and population average percentage change (from baseline) over time in diverse HRV metrics, in comparison with the time of clinical diagnosis and treatment of sepsis (defined as systemic inflammatory response syndrome along with clinically suspected infection requiring treatment). Of the 21 patients enrolled, 4 patients withdrew, leaving 17 patients who completed the study. Fourteen patients developed sepsis requiring antibiotic therapy, whereas 3 did not. On average, for 12 out of 14 infected patients, a significant (25%) reduction prior to the clinical diagnosis and treatment of sepsis was observed in standard deviation, root mean square successive difference, sample and multiscale entropy, fast Fourier transform, detrended fluctuation analysis, and wavelet variability metrics. For infected patients (n = 14), wavelet HRV demonstrated a 25% drop from baseline 35 h prior to sepsis on average. For 3 out of 3 non-infected patients, all measures, except root mean square successive difference and entropy, showed no significant reduction. Significant correlation was present amongst these HRV metrics for the entire population. Conclusions/Significance Continuous HRV monitoring is feasible in ambulatory patients, demonstrates significant HRV alteration in individual patients in association with, and prior to clinical diagnosis and treatment of sepsis, and merits further investigation as a means of providing early warning of sepsis.

The association between antiphospholipid antibodies and placenta mediated complications: A systematic review and meta-analysis

BACKGROUND The association between antiphospholipid antibodies (APLA) and placenta mediated pregnancy complications (pre-eclampsia, intrauterine growth restriction (IUGR), late fetal loss and placental abruption) remains controversial. METHODS We performed a systematic review of published case-control, cohort and cross sectional studies (MEDLINE (1975 to 2009), EMBASE 16 (1980 to 2009) and all EBM Reviews (2009)) to evaluate the association between APLA and placenta mediated complications in untreated women without autoimmune diseases. RESULTS Our search strategy identified 1207 potentially relevant studies. Twenty eight were included in the final analysis. LA was associated with pre-eclampsia (OR 2.34; 95% CI 1.18-4.64), IUGR (OR 4.65 95% CI 1.29-16.71) and late fetal loss (OR 4.73; 95% CI 1.08-20.81) amongst case-control studies and only with late fetal loss (OR 10.59 95% CI 1.87-59.88) amongst cohort studies. ACA were associated with pre-eclampsia (OR 1.52; 95% CI 1.05-2.20) and late fetal loss (OR 4.29; 95% CI 1.34-13.68) amongst case-control studies and only late fetal loss (OR 8.85 95% CI 1.84-42.50) amongst cohort studies. Finally, anti-B2 GP1 antibodies showed associations with pre-eclampsia (OR 19.14, 95% CI 6.34-57.77), IUGR (OR 20.03; 95% CI 4.59-87.43) and late fetal loss (OR 23.46, 95% CI 1.21-455.01) in two cohort studies. CONCLUSION APLAs appear to be associated with late fetal losses. However, the association between APLAs and other placenta mediated complications is inconsistent. LA is most strongly and consistently associated with placenta mediated complications. There are currently insufficient data to support a significant link between anti-B2 GP1 antibodies and pregnancy morbidity.

Aspirin versus low-molecular-weight heparin for extended venous thromboembolism prophylaxis after total hip arthroplasty: a randomized trial.

BACKGROUND The role of aspirin in thromboprophylaxis after total hip arthroplasty (THA) is controversial. OBJECTIVE To compare extended prophylaxis with aspirin and dalteparin for prevention of symptomatic venous thromboembolism (VTE) after THA. DESIGN Multicenter randomized, controlled trial with a noninferiority design based on a minimal clinically important difference of 2.0%. Randomization was electronically generated; patients were assigned to a treatment group through a Web-based program. Patients, physicians, study coordinators, health care team members, outcome adjudicators, and data analysts were blinded to interventions. (Current Controlled Trials: ISRCTN11902170). SETTING 12 tertiary care orthopedic referral centers in Canada. PATIENTS 778 patients who had elective unilateral THA between 2007 and 2010. INTERVENTION After an initial 10 days of dalteparin prophylaxis after elective THA, patients were randomly assigned to 28 days of dalteparin (n = 400) or aspirin (n = 386). MEASUREMENTS Symptomatic VTE confirmed by objective testing (primary efficacy outcome) and bleeding. RESULTS Five of 398 patients (1.3%) randomly assigned to dalteparin and 1 of 380 (0.3%) randomly assigned to aspirin had VTE (absolute difference, 1.0 percentage point [95% CI, -0.5 to 2.5 percentage points]). Aspirin was noninferior (P < 0.001) but not superior (P = 0.22) to dalteparin. Clinically significant bleeding occurred in 5 patients (1.3%) receiving dalteparin and 2 (0.5%) receiving aspirin. The absolute between-group difference in a composite of all VTE and clinically significant bleeding events was 1.7 percentage points (CI, -0.3 to 3.8 percentage points; P = 0.091) in favor of aspirin. LIMITATION The study was halted prematurely because of difficulty with patient recruitment. CONCLUSION Extended prophylaxis for 28 days with aspirin was noninferior to and as safe as dalteparin for the prevention of VTE after THA in patients who initially received dalteparin for 10 days. Given its low cost and greater convenience, aspirin may be considered a reasonable alternative for extended thromboprophylaxis after THA. PRIMARY FUNDING SOURCE Canadian Institutes of Health Research.

Risk of post-thrombotic syndrome after subtherapeutic warfarin anticoagulation for a first unprovoked deep vein thrombosis: results from the REVERSE study

Summary.  Background:  Risk factors for post‐thrombotic syndrome (PTS) remain poorly understood.

Predictors of post-thrombotic syndrome in a population with a first deep vein thrombosis and no primary venous insufficiency.

Post‐thrombotic syndrome (PTS) is the most frequent complication of deep vein thrombosis (DVT). Its diagnosis is based on clinical characteristics. However, symptoms and signs of PTS are non‐specific, and could result from concomitant primary venous insufficiency (PVI) rather than DVT. This could bias evaluation of PTS.