Time-based measures of treatment effect: reassessment of ticagrelor and clopidogrel from the PLATO trial

Ticagrelor-Related Dyspnea Beyond Adenosine: Insights into Retrotrapezoid Hyperactivity

Ticagrelor, a P2Y12 receptor antagonist, has been demonstrated to induce dyspnea, which is not associated with cardiac or pulmonary alterations, or metabolic disturbances. The attribution of ticagrelor-related dyspnea to excess adenosine has been widely proposed, yet is not supported by experimental data. In this paper, we put forth a novel hypothesis that the hyperactivity of the retrotrapezoid nucleus, a group of ventral medullary neurons involved in respiratory modulation, is the underlying cause of ticagrelor-related dyspnea. This hypothesis offers a theoretical resolution to the discrepancies and controversies present in previous theories.

Delaying clinical events among patients with non-valvular atrial fibrillation treated with oral anticoagulants: Insights from the ARISTOPHANES study

BACKGROUND

Oral anticoagulants (OACs) mitigate stroke and systemic embolism (SE) risk in non-valvular atrial fibrillation (AF) patients but can increase the risk of major bleeding (MB). This study analyzed the gains in event-free time for these outcomes among OAC treatment options represented in the ARISTOPHANES study.

METHODS

This sub-analysis consisted of NVAF patients who initiated warfarin, apixaban, dabigatran, or rivaroxaban from 01JAN2013-30SEP2015, with data pooled from Medicare and 4 US commercial claims databases. Propensity score matching was conducted between non-vitamin K antagonist OAC (NOAC) and warfarin cohorts in each database and results were pooled. Laplace regression was used to evaluate the delay in time to stroke/SE and MB events between NOACs and warfarin and between NOACs after the first 12-months of follow-up.

RESULTS

The population included 466,991 patients (167,413 warfarin; 108,852 apixaban; 37,724 dabigatran; and 153,002 rivaroxaban). Event-free time gain (95% confidence interval) for apixaban versus warfarin was 101 days (78- 124) for stroke/SE and 116 (103- 130) days for MB. The gain in event-free time for dabigatran versus warfarin was 45 days (3- 87) for stroke/SE and 92 (68- 116) days for MB. The gain in event-free time for rivaroxaban versus warfarin was 63 days (42- 84) for stroke/SE but event-free time decreased by 18 (-31-6) days for MB.

CONCLUSIONS

Over 12 months after initiation, apixaban and dabigatran conferred progressive increases in event free time for stroke/SE and MB vs warfarin, whereas rivaroxaban conferred an increase in stroke/SE-free time but a loss in MB-free time vs warfarin.

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet agents may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased. This is an update of a review first published in 2013.

OBJECTIVES

To evaluate the benefits and harms of antiplatelet agents in people with any form of CKD, including those with CKD not receiving renal replacement therapy, patients receiving any form of dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 13 July 2021 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet agents versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Four authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data were pooled using the random-effects model. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 113 studies, enrolling 51,959 participants; 90 studies (40,597 CKD participants) compared an antiplatelet agent with placebo or no treatment, and 29 studies (11,805 CKD participants) directly compared one antiplatelet agent with another. Fifty-six new studies were added to this 2021 update. Seven studies originally excluded from the 2013 review were included, although they had a follow-up lower than two months. Random sequence generation and allocation concealment were at low risk of bias in 16 and 22 studies, respectively. Sixty-four studies reported low-risk methods for blinding of participants and investigators; outcome assessment was blinded in 41 studies. Forty-one studies were at low risk of attrition bias, 50 studies were at low risk of selective reporting bias, and 57 studies were at low risk of other potential sources of bias. Compared to placebo or no treatment, antiplatelet agents probably reduces myocardial infarction (18 studies, 15,289 participants: RR 0.88, 95% CI 0.79 to 0.99, I² = 0%; moderate certainty). Antiplatelet agents has uncertain effects on fatal or nonfatal stroke (12 studies, 10.382 participants: RR 1.01, 95% CI 0.64 to 1.59, I² = 37%; very low certainty) and may have little or no effect on death from any cause (35 studies, 18,241 participants: RR 0.94, 95 % CI 0.84 to 1.06, I² = 14%; low certainty). Antiplatelet therapy probably increases major bleeding in people with CKD and those treated with haemodialysis (HD) (29 studies, 16,194 participants: RR 1.35, 95% CI 1.10 to 1.65, I² = 12%; moderate certainty). In addition, antiplatelet therapy may increase minor bleeding in people with CKD and those treated with HD (21 studies, 13,218 participants: RR 1.55, 95% CI 1.27 to 1.90, I² = 58%; low certainty). Antiplatelet treatment may reduce early dialysis vascular access thrombosis (8 studies, 1525 participants) RR 0.52, 95% CI 0.38 to 0.70; low certainty). Antiplatelet agents may reduce doubling of serum creatinine in CKD (3 studies, 217 participants: RR 0.39, 95% CI 0.17 to 0.86, I² = 8%; low certainty). The treatment effects of antiplatelet agents on stroke, cardiovascular death, kidney failure, kidney transplant graft loss, transplant rejection, creatinine clearance, proteinuria, dialysis access failure, loss of primary unassisted patency, failure to attain suitability for dialysis, need of intervention and cardiovascular hospitalisation were uncertain. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, including prasugrel, ticagrelor, different doses of clopidogrel, abciximab, defibrotide, sarpogrelate and beraprost.

AUTHORS' CONCLUSIONS

Antiplatelet agents probably reduced myocardial infarction and increased major bleeding, but do not appear to reduce all-cause and cardiovascular death among people with CKD and those treated with dialysis. The treatment effects of antiplatelet agents compared with each other are uncertain.

Effects of apixaban compared with warfarin as gain in event-free time - a novel assessment of the results of the ARISTOTLE trial

BACKGROUND

A novel approach to determine the effect of a treatment is to calculate the delay of event, which estimates the gain of event-free time. The aim of this study was to estimate gains in event-free time for stroke or systemic embolism, death, bleeding events, and the composite of these events, in patients with atrial fibrillation randomized to either warfarin or apixaban in the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation trial (ARISTOTLE).

DESIGN

The ARISTOTLE study was a randomized double-blind trial comparing apixaban with warfarin.

METHODS

Laplace regression was used to estimate the delay in time to the outcomes between the apixaban and the warfarin group in 6, 12, 18 and 22 months of follow-up.

RESULTS

The gain in event-free time for apixaban versus warfarin was 181 (95% confidence interval 76 to 287) days for stroke or systemic embolism and 55 (-4 to 114) days for death after 22 months of follow-up. The corresponding gains in event-free times for major and intracranial bleeding were 206 (130 to 281) and 392 (249 to 535) days, respectively. The overall gain for the composite of all these events was a gain of 116 (60 to 171) days.

CONCLUSIONS

In patients with atrial fibrillation, 22 months of treatment with apixaban, as compared with warfarin, provided gains of approximately 6 months in event-free time for stroke or systemic embolism, 7 months for major bleeding and 13 months for intracranial bleeding.

Length of time periods in treatment effect descriptions and willingness to initiate preventive therapy: a randomised survey experiment

Background

Common measures used to describe preventive treatment effects today are proportional, i.e. they compare the proportions of events in relative or absolute terms, however they are not easily interpreted from the patient’s perspective and different magnitudes do not seem to clearly discriminate between levels of effect presented to people.

Methods

In this randomised cross-sectional survey experiment, performed in a Swedish population-based sample (n = 1041, response rate 58.6%), the respondents, aged between 40 and 75 years were given information on a hypothetical preventive cardiovascular treatment. Respondents were randomised into groups in which the treatment was described as having the effect of delaying a heart attack for different periods of time (Delay of Event, DoE): 1 month, 6 months or 18 months. Respondents were thereafter asked about their willingness to initiate such therapy, as well as questions about how they valued the proposed therapy.

Results

Longer DoE:s were associated with comparatively greater willingness to initiate treatment. The proportions accepting treatment were 81, 71 and 46% when postponement was 18 months, 6 months and 1 month respectively. In adjusted binary logistic regression models the odds ratio for being willing to take therapy was 4.45 (95% CI 2.72–7.30) for a DoE of 6 months, and 6.08 (95% CI 3.61–10.23) for a DoE of 18 months compared with a DoE of 1 month. Greater belief in the necessity of medical treatment increased the odds of being willing to initiate therapy.

Conclusions

Lay people’s willingness to initiate preventive therapy was sensitive to the magnitude of the effect presented as DoE. The results indicate that DoE is a comprehensible effect measure, of potential value in shared clinical decision-making.