Systematic review of observational studies assessing bleeding risk in patients with atrial fibrillation not using anticoagulants

Treatment effect modification due to comorbidity: Individual participant data meta-analyses of 120 randomised controlled trials

BACKGROUND

People with comorbidities are underrepresented in clinical trials. Empirical estimates of treatment effect modification by comorbidity are lacking, leading to uncertainty in treatment recommendations. We aimed to produce estimates of treatment effect modification by comorbidity using individual participant data (IPD).

METHODS AND FINDINGS

We obtained IPD for 120 industry-sponsored phase 3/4 trials across 22 index conditions (n = 128,331). Trials had to be registered between 1990 and 2017 and have recruited ≥300 people. Included trials were multicentre and international. For each index condition, we analysed the outcome most frequently reported in the included trials. We performed a two-stage IPD meta-analysis to estimate modification of treatment effect by comorbidity. First, for each trial, we modelled the interaction between comorbidity and treatment arm adjusted for age and sex. Second, for each treatment within each index condition, we meta-analysed the comorbidity-treatment interaction terms from each trial. We estimated the effect of comorbidity measured in 3 ways: (i) the number of comorbidities (in addition to the index condition); (ii) presence or absence of the 6 commonest comorbid diseases for each index condition; and (iii) using continuous markers of underlying conditions (e.g., estimated glomerular filtration rate (eGFR)). Treatment effects were modelled on the usual scale for the type of outcome (absolute scale for numerical outcomes, relative scale for binary outcomes). Mean age in the trials ranged from 37.1 (allergic rhinitis trials) to 73.0 (dementia trials) and percentage of male participants range from 4.4% (osteoporosis trials) to 100% (benign prostatic hypertrophy trials). The percentage of participants with 3 or more comorbidities ranged from 2.3% (allergic rhinitis trials) to 57% (systemic lupus erythematosus trials). We found no evidence of modification of treatment efficacy by comorbidity, for any of the 3 measures of comorbidity. This was the case for 20 conditions for which the outcome variable was continuous (e.g., change in glycosylated haemoglobin in diabetes) and for 3 conditions in which the outcomes were discrete events (e.g., number of headaches in migraine). Although all were null, estimates of treatment effect modification were more precise in some cases (e.g., sodium-glucose co-transporter-2 (SGLT2) inhibitors for type 2 diabetes-interaction term for comorbidity count 0.004, 95% CI -0.01 to 0.02) while for others credible intervals were wide (e.g., corticosteroids for asthma-interaction term -0.22, 95% CI -1.07 to 0.54). The main limitation is that these trials were not designed or powered to assess variation in treatment effect by comorbidity, and relatively few trial participants had >3 comorbidities.

CONCLUSIONS

Assessments of treatment effect modification rarely consider comorbidity. Our findings demonstrate that for trials included in this analysis, there was no empirical evidence of treatment effect modification by comorbidity. The standard assumption used in evidence syntheses is that efficacy is constant across subgroups, although this is often criticised. Our findings suggest that for modest levels of comorbidities, this assumption is reasonable. Thus, trial efficacy findings can be combined with data on natural history and competing risks to assess the likely overall benefit of treatments in the context of comorbidity.

Atrial Fibrillation Detection and Management in Hypertension

Hypertension is prevalent in >70% of atrial fibrillation patients. In turn, hypertensive patients have up to 73% greater likelihood of atrial fibrillation. Current guidelines recommend that a systematic atrial fibrillation screening may be justified in all patients aged ≥65 years with at least 1 cardiovascular disease, including hypertension. Although most blood pressure monitors include algorithms to detect atrial fibrillation with a high sensitivity of 96 [92-98]% and specificity of 94 [91-96]%, an electrocardiography confirmation is necessary to establish a diagnosis of atrial fibrillation. Early detection and diagnosis of atrial fibrillation is important to allow initiation of atrial fibrillation management. In the Early Treatment of Atrial Fibrillation for Stroke Prevention Trial (EAST-AFNET 4), hypertension was present in 88% of participants, and early rhythm control therapy lowered the risk of adverse cardiovascular outcomes in patients with early atrial fibrillation aged >75 or with CHA₂DS₂-VASc score ≥2 (Congestive heart failure, Hypertension, Age ≥75 (doubled), Diabetes, Stroke (doubled), Vascular disease, Age 65-74, Sex category [female]) and cardiovascular condition. Strategies for early atrial fibrillation detection should always be linked to a comprehensive atrial fibrillation work-up infrastructure organized within an integrated ABC pathway (Anticoagulation/Avoid stroke; Better symptom control; Cardiovascular and Comorbidity optimization). For secondary prophylaxis, blood pressure control should be embedded in a combined risk factor management program. In hypertensive patients where no atrial fibrillation is detected, intensive blood pressure lowering therapy for primary prophylaxis should be initiated to reduce the risk of developing atrial fibrillation and other cardiovascular complications in the future. The aim of the article is to review the current literature on atrial fibrillation detection and management in hypertensive patients.

Hypertension and atrial fibrillation

Hypertension is the most prevalent cardiovascular risk factor underlying atrial fibrillation and is present in up to 40% of patients with atrial fibrillation. Furthermore, attributable risk studies have shown that a history of hypertension contributes to up to 24% of incident atrial fibrillation. New data suggest that even early forms of hypertension (prehypertension and aortic stiffness) are associated with an increased risk of atrial fibrillation development. Hypertension and prehypertension are therefore critical mediators for the development of atrial fibrillation. Mechanisms for the association between hypertension and atrial fibrillation include diffuse electro-structural changes to the left atrium, driven by the haemodynamic and neurohormonal influences of hypertension and other, frequently coexisting, cardiovascular risk factors. Management of hypertension in atrial fibrillation should focus not only on blood pressure reduction but also on a comprehensive risk factor modification strategy. Such strategies have been shown to be associated with significant improvements in atrial fibrillation symptom burden as well as improved arrhythmia-free survival and reversal of the progression of atrial fibrillation. These strategies should focus on dietary modifications as well as prescribed exercise programmes involving a multidisciplinary team and patient-centred atrial fibrillation care. Risk factor management, supplemented by antihypertensive medications as needed, provides the optimum strategy for improving outcomes and even reversing the natural progression of atrial fibrillation in patients with hypertension.

Bleeding risks with novel oral anticoagulants especially rivaroxaban versus aspirin: a meta-analysis

Background

This pairwise meta-analysis determines the difference in bleeding risks associated with the use of novel oral anticoagulants (NOACs) and aspirin.

Methods

PubMed, the Cochrane Library database, clinicaltrial.gov, and related studies were searched for randomized control trials (RCTs) comparing NOAC and aspirin published between January 1, 2000 and May 10, 2021. The primary endpoint was intracranial hemorrhage (ICH).

Results

Eleven studies involving 57,645 patients were included. Compared to aspirin, rivaroxaban (5 mg/day) had a similar risk of ICH, major bleeding, and fatal bleeding; rivaroxaban (10 mg/day) had higher risks of gastrointestinal hemorrhage (OR: 1.41; 95% CI: 1.03–1.94; P = 0.032; I² = 0%) and a similar risk of ICH, major bleeding, and fatal bleeding; and rivaroxaban (15–20 mg/day) had higher risks of ICH (OR: 3.21; 95% CI: 1.36–7.60; P = 0.008; I² = 0%), major bleeding (OR: 2.64; 95% CI: 1.68–4.16; P < 0.001; I² = 0%), and fatal bleeding (OR: 2.26; 95% CI: 1.25–4.08; P = 0.007; I² = 0%) and a similar risk of gastrointestinal hemorrhage. Bleeding outcomes between other NOACs (apixaban and dabigatran etexilate) and aspirin were not different.

Conclusions

The bleeding risks associated with NOACs depend on drug type and dosage. For ≥15 mg/day of rivaroxaban, the risk of ICH was significantly higher than that with aspirin. However, further studies comparing dabigatran etexilate and apixaban versus aspirin are warranted to draw a definite conclusion.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-021-00322-6.

Clinical characteristics and antithrombotic prescription in elderly hospitalized atrial fibrillation patients: A cross-sectional analysis of a Swedish single-center clinical cohort

BACKGROUND

Antithrombotic treatment represents a dilemma in elderly patients with atrial fibrillation since both risk of thromboembolism and bleeding are age-dependent complications. A paradigm shift occurred over the past 10 years when aspirin was overcome by warfarin and further by the direct oral anticoagulants. Here we present a clinical practice-based analysis of a cohort of elderly inpatient atrial fibrillation patients and investigate the influence of clinical factors in the choice of antithrombotic strategy.

METHODS

Study participants (n = 2943) are consecutive patients aged 75-104 years discharged from a Swedish university hospital with atrial fibrillation or atrial flutter as main diagnosis between November 1st 2010 and December 31st 2017. Cardiovascular risk factors, comorbidities and antithrombotic treatment at discharge were manually extracted from medical charts. A logistic regression analysis was performed to estimate predictors of the probability to receive direct oral anticoagulants (DOACs) compared to warfarin.

RESULTS

Patients aged ≥90 y (n = 446, women 73%) showed the highest prevalence of cardiovascular comorbidities and the highest bleeding and thromboembolic risk. DOACs became more commonly prescribed than warfarin in 2016/2017 across all ages. However, the probability to receive DOAC as compared to warfarin was lower in the presence of high bleeding risk (OR 0,55; 95% CI 0,40-0,77; p = 0,00) and high thromboembolic risk (OR 0,74; 95% CI 0,59-0,94; p = 0,01).

CONCLUSION

Elderly atrial fibrillation patients represent a heterogenous group where the oldest (≥90 years) show both a very high thromboembolic and bleeding risk profile. In the presence of high thromboembolic and bleeding risk, warfarin was still preferred over DOAC.

Association of Intracranial Hemorrhage Risk With Non-Vitamin K Antagonist Oral Anticoagulant Use vs Aspirin Use: A Systematic Review and Meta-analysis

Importance

Non-vitamin K antagonist oral anticoagulants (NOACs) might be an attractive choice for stroke prevention in people without atrial fibrillation who may harbor a potential source of cardiac emboli, but not if certain individual NOACs carry risks of intracranial hemorrhage that are heightened relative to aspirin.

Objective

To conduct a systematic review and meta-analysis of randomized clinical trials to assess the risk of intracranial hemorrhage with individual NOACs vs aspirin across all indications.

Data Sources

We searched PubMed, Embase, CENTRAL, and ClinicalTrials.gov from inception to May 28, 2018, with the terms novel oral anticoagulants, non-vitamin K antagonist oral anticoagulants, direct oral anticoagulants, dabigatran, rivaroxaban, apixaban, edoxaban, warfarin, Coumadin, vitamin K antagonist, aspirin, acetylsalicylic acid, or ASA, and major bleeding, fatal bleeding, or intracranial hemorrhage. We restricted our search to clinical trials on humans. There were no language restrictions.

Study Selection

Randomized clinical trials of 3 months or longer that included a comparison of the outcomes of NOAC use vs use of aspirin.

Data Extraction and Synthesis

Two investigators independently abstracted data from eligible studies. We computed a fixed-effect estimate based on the Mantel-Haenszel method.

Main Outcomes and Measures

Odds ratios (ORs) with 95% CI were used as a measure of the association of individual NOAC vs aspirin with the risk of intracranial hemorrhage. The hypothesis that intracranial hemorrhage risk would be higher with NOACs than aspirin was formulated during data collection.

Results

Our principal analysis included 5 randomized clinical trials comparing 1 or more NOACs with aspirin, with 39 398 individuals enrolled. Pooling the results from the fixed-effects model showed that a dose of 15 to 20 mg of rivaroxaban once daily was associated with an increased risk of intracranial hemorrhage (2 trials; OR, 3.31 [95% CI, 1.42 to 7.72]) compared with aspirin, while a 10-mg dose of rivaroxaban once daily or a 5-mg dose twice daily (3 trials; OR, 1.43 [95% CI, 0.93 to 2.21]) and a 5-mg dose of apixaban twice daily (1 trial; OR, 0.84 [95% CI, 0.38 to 1.88]) were not.

Conclusions and Relevance

A 15-mg to 20-mg dose of rivaroxaban once daily is associated with substantially increased risks of intracranial hemorrhage, while smaller daily doses of rivaroxaban and apixaban were not, implying that risk increase is dose dependent. It may be worthwhile to conduct randomized clinical trials comparing specific NOACs in specific doses (eg, apixaban, 5 mg twice daily) and aspirin in patients without atrial fibrillation, but with potential sources of cardiac emboli that could cause stroke.

Assessing bleeding risk in 4824 Asian patients with atrial fibrillation: The Beijing PLA Hospital Atrial Fibrillation Project

The risks of major bleeding and intracranial hemorrhage (ICH) are higher in Asian patients with atrial fibrillation (AF) compared to non-Asians. We aimed to investigate risk factors for bleeding, and validate the predictive value of available bleeding risk scores (mOBRI, HEMORR2HAGES, Shireman, HAS-BLED, ATRIA and ORBIT) in a large cohort of Chinese inpatients with AF. Using hospital electronic medical databases, we identified 4824 AF patients (mean age 67 years; 34.9% female) from January 1, 1995 to May 30, 2015, with median (interquartile) in-hospital days of 10 (7-16) days. On multivariate analysis, prior bleeds, vascular disease, anemia, prior stroke, and liver dysfunction were independent risk factors of major bleeding (all p < 0.05). C-statistics (95%CI) of the HAS-BLED score were 0.72 (0.65-0.79) for major bleeding events and 0.83 (0.75-0.91) for ICH (all p < 0.001). Compared to other risk scores, the HAS-BLED score was significantly better in predicting major bleeding events (Delong test, all P < 0.05, apart from mOBRI, HEMORR2HAGES) and ICH (all p < 0.05), and additionally, resulted in a net reclassification improvement (NRI) of 17.1-65.5% in predicting major bleeding events and 29.5-67.3% in predicting ICH (all p < 0.05). We conclude that the HAS-BLED score had the best predictive and discriminatory ability for major bleeding and ICH in an Asian/Chinese AF population.