Net clinical benefit outcome should be standardized in trials evaluating antithrombotic drugs: the example of NOACs in atrial fibrillation

Anticoagulation therapy in patients with post-operative atrial fibrillation: Systematic review with meta-analysis

BACKGROUND

Post-operative atrial fibrillation (POAF) is a relevant complication after surgery. Several studies have shown that POAF has important consequences for long-term morbidity and mortality, by increasing the risk of thromboembolic events. However, the use of oral anticoagulation (OAC) is not well established in this context.

METHODS

We searched MEDLINE, CENTRAL, PsycInfo and Web of Science for clinical trials and observational studies evaluating anticoagulation vs. no anticoagulation in patients with POAF (after cardiac or non-cardiac surgery). Data were screened and extracted by two independent reviewers. We performed a random- effects model to estimate the pooled odds ratio (OR) with 95% Confidence Intervals (CI), and heterogeneity was evaluated by I² statistics. The outcomes of interest were all-cause mortality, thromboembolic events, and bleeding events.

RESULTS

Overall, 10 observational retrospective studies were included: 5 studies with 203,946 cardiac surgery POAF patients, and 5 studies with 29,566 patients with POAF after non-cardiac surgery. In cardiac surgery POAF, the OAC use was associated with lower risk of thromboembolic events (OR 0.68; 95%CI 0.47-0.96, I² = 31%; 4 studies) and the bleeding risk was significantly increased (OR 4.30; 95%CI 3.69 to 5.02, 1 study). In non-cardiac surgery POAF, OAC did not significantly reduce the risk of thromboembolic events (OR 0.71, 95%CI 0.33-1.15; I² = 79%; 5 studies) but was associated with increased risk of bleeding (OR 1.20, 95%CI 1.10-1.32, I² = 0%; 3 studies). Mortality was not significantly reduced in both cardiac and non-cardiac surgery POAF.

CONCLUSION

Oral anticoagulation was associated with a lower risk of thromboembolic events in patients with POAF following cardiac surgery but not in non-cardiac surgery. Bleeding risk was increased in both settings. The confidence on pooled results is at most low, and further data, namely randomized controlled trials are necessary to derive robust conclusions.

Once- versus Twice-Daily Aspirin in Patients at High Risk of Thrombotic Events: Systematic Review and Meta-Analysis

BACKGROUND

Acetylsalicylic acid (ASA) is a frequently used antiplatelet agent, although some individuals have reduced antiplatelet responses on ASA, with recurrent ischemic events. It has been proposed that shortening the ASA dosing interval may overcome the time-dependent renewal of the drug target, leading to a greater antiplatelet effect. We conducted a systematic review of randomized controlled trials (RCTs) to determine the efficacy of once- versus twice-daily ASA in conditions with increased platelet turnover.

METHODS

We conducted a systematic review and meta-analysis by searching the CENTRAL, MEDLINE, and Embase databases for RCTs assessing once- versus twice-daily ASA. Data were screened, extracted, and appraised by two independent reviewers, and were pooled using a random-effects model. The primary outcomes were major adverse cardiovascular events (MACEs) and serum thromboxane B2 (TxB2). Other pharmacodynamic measures were retrieved as secondary outcomes. Results were reported as mean differences with corresponding 95% confidence intervals (CIs). We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Seven RCTs were included, enrolling 379 participants overall. None of the studies reported clinical outcomes. Pooled results showed that compared with once-daily ASA, twice-daily ASA was associated with a decrease in mean TxB2 of 1.42 ng/mL (95% CI - 2.71 to - 0.13; I² = 66%). We found no differences in subgroup analyses based on disease subtype, trial blinding, or trial design. A greater antiplatelet activity of the twice-daily regimen was also found when using PFA-100-ADP methods, although not when using the VerifyNow, LTA-AA, and multiplate methods.

CONCLUSIONS

Twice-daily ASA was associated with a greater antiplatelet effect compared with standard once-daily ASA.

Aspirin in the primary prevention of cardiovascular disease on diabetic patients: Systematic review and meta-analysis

AIMS

The publication of new trials brought additional data to the controversial topic of aspirin use in diabetic patients for primary prevention. Therefore, we aimed to systematically review all randomized controlled trials evaluating the clinical impact of aspirin in this setting.

METHODS

We searched for randomized controlled trials (RCTs) evaluating the impact of aspirin in patients with diabetes in primary prevention, in MEDLINE, EMBASE, CENTRAL (November/2018). The primary outcomes were all-cause mortality and the composite outcome of major adverse cardiovascular events (MACE). A meta-analysis was performed deriving risk ratios (RR) and 95% confidence intervals (CI).

RESULTS

All-cause mortality was not significantly reduced with RR 0.96 (95% CI 0.90-1.03; 7RCT; 27,595 patients). Regarding MACE, there was an 8% risk reduction (RR 0.92, 95% CI 0.84-0.999; I²=0%; 8RCT; 29,814 patients). The risks of major bleeding (RR 1.30, 95% CI 1.10-1.53; 2RCTs, 18,019 patients), and major GI bleeding (RR 1.39, 95% CI 1.08-1.80; 2RCTs, 18,019 patients) were significantly increased. The risks of cardiovascular mortality, myocardial infarction, stroke and amputation were not significantly different from control arm.

CONCLUSIONS

Aspirin use among diabetic patients in primary prevention appears was associated with increased risk of major bleeding, a modest decrease of MACE and lack of mortality benefit.

Thromboprophylaxis With Apixaban in Patients Undergoing Major Orthopedic Surgery: Meta-Analysis and Trial-Sequential Analysis

BACKGROUND

Venous thromboembolism (VTE) is a potentially fatal complication of orthopedic surgery, and until recently, few antithrombotic compounds were available for postoperative thromboprophylaxis. The introduction of the non–vitamin K antagonists oral anticoagulants (NOAC), including apixaban, has extended the therapeutic armamentarium in this field. Therefore, estimation of NOAC net clinical benefit in comparison with the established treatment is needed to inform clinical decision making.

OBJECTIVES

Systematic review to assess the efficacy and safety of apixaban 2.5 mg twice a day versus low-molecular-weight heparins (LMWH) for thromboprophylaxis in patients undergoing knee or hip replacement.

DATA SOURCES

MEDLINE, Embase, and CENTRAL were searched from inception to September 2016, other systematic reviews, reference lists, and experts were consulted.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTION

All major orthopedic surgery randomized controlled trials comparing apixaban 2.5 mg twice daily with LMWH, reporting thrombotic and bleeding events.

DATA EXTRACTION

Two independent reviewers, using a predetermined form.

STUDY APPRAISAL AND SYNTHESIS METHODS

The Cochrane tool to assess risk bias was used by two independent authors. RevMan software was used to estimate pooled risk ratio (RR) and 95% confidence intervals (95% CI) using random-effects meta-analysis. Trial sequential analysis (TSA) was performed in statistical significant results to evaluate whether cumulative sample size was powered for the obtained effect. Overall confidence in cumulative evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group methodology.

RESULTS

Four studies comparing apixaban 2.5 mg twice daily with LMWH were included, with a total of 11.828 patients (55% undergoing knee and 45% hip replacement). The overall risk of bias across studies was low. In comparison with LMWH (all regimens), apixaban showed a significantly lower risk of VTE events and overall mortality combined (RR: 0.63, 95% CI: 0.42–0.95, I2 = 84%, n = 8346), but not of major VTE events (RR: 0.62, 95% CI: 0.32–1.19, I2 = 63%, n = 9493), or of symptomatic VTE events and VTE-related mortality combined (RR: 1.14, 95% CI: 0.68–1.90, I2 = 0%, n = 11 879). Trial sequential analysis showed that the risk reduction obtained for VTE and mortality was based on underpowered cumulative sample size and effect dimension. Subgroup analysis according to LMWH regimens showed that apixaban reduced the risk of VTE events and overall mortality, and major VTE events, when compared with LMWH once daily, without differences between apixaban and LMWH twice daily.

CONCLUSIONS

There is low to moderate evidence that in patients undergoing knee or hip replacement, apixaban seems equally effective and safe to LMWH twice a day. When compared with LMWH once a day, apixaban seems a superior thromboprophylaxis option. However, the results are underpowered which precludes definite answers regarding the true net clinical benefit of apixaban versus LMWH in this clinical context.