Randomised controlled trials in cardiovascular medicine: past achievements, future challenges

Comparative analysis of level of evidence and class of recommendation for 50 clinical practice guidelines released by the European Society of Cardiology from 2011 to 2022

BACKGROUND

The European Society of Cardiology (ESC) clinical practice guidelines are essential tools for decision-making.

AIM

To analyze the level of evidence (LOE) and the class of recommendations in the ESC guidelines released in the last 12 years.

METHODS

We evaluated 50 ESC guidelines released from 2011 to 2022, related to 27 topics and categorized them into seven macro-groups. We analyzed every recommendation in terms of LOE and class of recommendation, calculating their relative proportions and changes over time in consecutive editions of the same guideline.

RESULTS

A total of 6972 recommendations were found, with an increase in number per year over time. Among the 50 ESC guidelines, the proportional distribution of classes of recommendations was 49% for Class I, 29% for Class IIa, 15% for Class IIb, and 8% for Class III. Overall, 16% of the recommendations were classified as LOE A, 31% LOE B and 53% LOE C. The field of preventive cardiology had the largest proportion of LOE A, while the lowest was in the field of valvular, myocardial, pericardial and pulmonary diseases. The overall proportion of LOE A recommendations in the most recent guidelines compared to their prior versions increased from 17% to 20%.

CONCLUSIONS

The recommendations included in the ESC guidelines widely differ in terms of quality of evidence, with only 16% supported by the highest quality of evidence. Although a slight global increase in LOE A recommendations was observed in recent years, further scientific research efforts are needed to increase the quality of evidence.

The participation of Arab women in randomised clinical trials for cardiovascular diseases

INTRODUCTION

Women's enrolment in randomised clinical trials (RCTs) raises the attention of medical personnel and evidence-based medicine researchers to achieve the highest possible quality and transparency of conducted studies. This study aims to demonstrate various patterns and relationships of women's enrolment in cardiovascular RCTs conducted in Arab countries.

MATERIALS AND METHODS

Three databases (PubMed, Web of Science and Scopus) were accessed and searched for randomised clinical trials investigating cardiovascular diseases in Arab countries. Studies were screened, data were extracted and risk of bias of included studies was assessed independently by two sets of authors. The female to male ratio and the participation prevalence ratio (PPR) were calculated for each trial and the association of them with different variables were analysed.

RESULTS AND DISCUSSION

Of the 9071 patients enrolled in the 71 included RCTs, 38.02% were women. Various factors such as age of participants, publication year, therapeutic class, clinical indication, prevention type, and location of trial showed a significant association with the level of women enrolment in cardiovascular randomised clinical trials in Arab countries (P-value < .05). The median female to male ratio of all the trials was 0.55. The median female: male ratio varied by clinical indications (2.33 for valvular heart diseases vs 0.5 for stroke), intervention type (0.46 for surgical procedures vs 0.52 for drugs), prevention type (0.79 for secondary prevention, 0.74 for primary prevention and 0.52 for tertiary prevention), sample size (0.48 for Q1 vs 0.85 for Q2) and by age groups (0.98 for ages ≤50 years old vs 0.47 for 56-60 years old). Women were overrepresented in valvular heart disease trials (PPR = 1.37), and underrepresented in coronary artery disease, stroke and atrial fibrillation trials (PPR = 0.6, 0.63, and 0.71, respectively).

CONCLUSION

As a result of the huge importance of RCTs in the medical field, and to reduce biases arising from inaccurate representation of different study populations, women's enrolment in Arab cardiovascular trials should be pre-planned and based on the percentage of women among the studied disease population.

Assessing the Quality of Abstracts in Randomized Controlled Trials Published in High Impact Cardiovascular Journals

BACKGROUND

In the busy world of cardiovascular medicine, abstracts may be the only part of a publication that clinicians read. Therefore, it is critical for abstracts to accurately reflect article content. The extended CONSORT (Consolidated Standards of Reporting Trials) Statement for Abstracts was developed to ensure high abstract quality. However, it is unknown how often adherence to CONSORT guidelines occurs among cardiovascular journals.

METHODS AND RESULTS

We searched MEDLINE for randomized controlled trials published in 3 major cardiovascular journals ( Circulation, Journal of the American College of Cardiology, and European Heart Journal) from 2011 to 2017. Post hoc, interim, and cost-effective analyses of randomized controlled trials were excluded. Two independent investigators extracted the data using a prespecified data collection form and a third investigator adjudicated the data. The primary outcome was frequency of subcategory adherence to CONSORT guidelines. A total of 478 abstracts were included in the analysis. Approximately half of the abstracts (53%; 255/478; 95% CI, 49%-57%) identified the article as randomized in the title. All abstracts detailed the interventions for both study groups (100%) and 81% (95% CI, 78%-85%) reported trial registration. Methodological quality reporting was relatively low: 9% (45/478; 95% CI, 6%-12%) described participant eligibility criteria with settings for data collection, 43% (204/478; 95% CI, 39%-47%) reported details of blinding, and <1% (4/478; 95% CI, 0%-2%) reported allocation concealment. Approximately 60% (301/478; 95% CI, 59%-67%) of the included abstracts provided primary outcome results while 55% (262/478; 95% CI, 51%-60%) reported harms or adverse effects.

CONCLUSIONS

There is a high prevalence of nonadherence to CONSORT guidelines among leading cardiovascular journals. Efforts by editors, authors, and reviewers should be made to increase adherence and promote transparent and unbiased presentation of study results.

Canadian Network and Centre for Trials Internationally (CANNeCTIN): a national network for Canadian-led trials in cardiovascular diseases and diabetes mellitus

The Canadian Network and Centre for Trials INternationally (CANNeCTIN) was jointly funded by the Canadian Institutes of Health Research and the Canadian Foundation for Innovation in April 2008 to provide infrastructure for clinical studies of cardiovascular diseases and diabetes mellitus. Its functional components include a national coordinating centre at the Population Health Research Institute (PHRI) in Hamilton (Ontario), a collaborative Canadian network and an affiliated international network of hospitals and clinics. The rationales for CANNeCTIN include the global health burden of cardiovascular diseases and diabetes, the strengths of randomized controlled trials - particularly large, multicentre and international - and the track record of success of the PHRI. CANNeCTIN will provide investigators from across Canada with opportunities to become the principal investigators of national and international trials coordinated by the PHRI. CANNeCTIN will support priority pilot studies, and successful investigators will be encouraged and assisted to apply for peer review and industrial funding for full studies to be conducted within the network and coordinated by the PHRI. An extensive education program offers hands-on experience in organizing and leading large national⁄international clinical trials led by accomplished researchers, distance learning courses in clinical research methodology, biostatistics and study coordination, and 'cutting-edge' workshops. A knowledge translation program seeks opportunities arising from clinical trials and encourages research into this paradigm for understanding how best to close the gaps between knowledge and effective practice. The five-year goals are to enhance the capacity of Canadian investigators to lead major clinical studies, facilitate knowledge translation and exchange, and augment Canada's capacity to train the next generation of leaders in cardiovascular and diabetes clinical research.

An ethical hierarchy for decision making during medical emergencies

Evidence from well-designed clinical trials may guide clinicians, reduce regional variation, and lead to improved outcomes. Many physicians choose to ignore evidence-based practice guidelines. Using unproven therapies outside of a randomized trial slows recruitment in clinical trials that could yield information on clinical and economic efficacy. Using acute stroke therapy as an illustration, we present an ethical hierarchy for therapeutic decision making during medical emergencies. First, physicians should offer standard care. If no standard care option exists, the physician should consider enrollment in a randomized clinical trial. If no trial is appropriate, the physician should consider a nonrandomized registry, or consensus-based guidelines. Finally, only after considering the first 3 options, the physician should use best judgment based on previous personal experience and any published case series or anecdotes. Given the paucity of quality randomized clinical trial data for most medical decisions, the "best judgment" option will be used most frequently. Nevertheless, such a hierarchy is needed because of the limited time during medical emergencies for consideration of general principles of clinical decision making. There should be general agreement in advance as to the hierarchy to follow in selecting treatment for critically ill patients. Were more clinicians to follow this hierarchy, and choose to participate in clinical trials, the generation of new knowledge would accelerate, yielding rigorous data supporting or refuting the efficacy and safety of new interventions more quickly, thus benefiting far more patients over time.

The contribution of observational studies to the knowledge of drug effectiveness in heart failure

AIMS

Randomized controlled trials (RCTs) are the golden standard for the assessment of drug efficacy. Little is known about the add-on value of observational studies in heart failure (HF). We aimed to assess the contribution of observational studies to actual knowledge regarding the effectiveness of angiotensin-converting enzyme inhibitors (ACEI), and beta-blockers (BB) in HF.

METHODS

Observational studies that assessed the effectiveness of ACEI and BB in HF were identified by searching Medline, Embase, Cochrane Database (1990-2005) and the bibliographies of published articles. Cohort, case-control and time-series analysis studies were considered for inclusion. Studies with <100 patients and those who did not perform a multivariate analysis were excluded.

RESULTS

A total of 23 cohort studies met the inclusion criteria. Studies of ACEI and BB showed a decrease in mortality with drug use in elderly patients with a broad range of ejection fraction (EF), and in those with depressed EF. Additionally, they showed a decrease in mortality in patients with renal insufficiency. The effect of ACEI and BB in HF with preserved EF was not clear, although last evidence suggests a potential benefit. Low-dose ACEI and BB may have beneficial effects. Target doses of ACEI seemed superior to low doses, but there was no clear dose-response relationship.

CONCLUSIONS

Observational studies in HF validate the effectiveness of ACEI and BB in populations underrepresented or excluded from RCTs. Observational studies of drug effectiveness provide relevant additional information for clinical practice.

The relationship between antioxidant supplements and oxidative stress in renal transplant recipients: a review

Renal transplant recipients (RTRs) have elevated oxidative stress and a high incidence of cardiovascular morbidity and mortality. Although recent studies do not support the use of antioxidant supplements as a cardioprotectant in the general population, evidence suggests that RTRs may represent individuals that would benefit from this therapy. RTRs have elevated oxidative stress probably caused by the immunosuppressive therapy, and although only a small number of studies have examined the effects of antioxidant supplementation in these patients, most have reported beneficial findings. This review discusses these studies along with the rationale for the use of antioxidant supplements in RTRs and a call for more research to investigate this important topic.

Covariate adjustment in randomized controlled trials with dichotomous outcomes increases statistical power and reduces sample size requirements

OBJECTIVE

Randomized controlled trials (RCTs) with dichotomous outcomes may be analyzed with or without adjustment for baseline characteristics (covariates). We studied type I error, power, and potential reduction in sample size with several covariate adjustment strategies.

STUDY DESIGN AND SETTING

Logistic regression analysis was applied to simulated data sets (n=360) with different treatment effects, covariate effects, outcome incidences, and covariate prevalences. Treatment effects were estimated with or without adjustment for a single dichotomous covariate. Strategies included always adjusting for the covariate ("prespecified"), or only when the covariate was predictive or imbalanced.

RESULTS

We found that the type I error was generally at the nominal level. The power was highest with prespecified adjustment. The potential reduction in sample size was higher with stronger covariate effects (from 3 to 46%, at 50% outcome incidence and covariate prevalence) and independent of the treatment effect. At lower outcome incidences and/or covariate prevalences, the reduction was lower.

CONCLUSION

We conclude that adjustment for a predictive baseline characteristic may lead to a potentially important increase in power of analyses of treatment effect. Adjusted analysis should, hence, be considered more often for RCTs with dichotomous outcomes.

Evidence-based medicine in anesthesiology

By making the clinical decision making process explicit, conscious, and science based, we may avoid confusing opinion with evidence. EBM may help sharpen our critical appraisal skills and thus improve the way we practice, teach, and conduct research. Nevertheless, EBM will need to supplement rather than substitute for other approaches to patient care and teaching. EBM may better incorporate patients' values into clinical decision making, and this may be especially important in anesthesiology, where we are in need of valid evidence about important clinical issues such as preoperative testing and postoperative analgesia. By incorporating valid scientific evidence and patients' values into clinical decision making, we may improve patient outcomes. Outside of internal medicine, the literature suggesting that the practice of EBM improves outcomes is sparse, though increasing. Future studies to critically evaluate the practice of EBM in anesthesiology and critical care would be helpful.

The current status of primary prevention in coronary heart disease

During the second part of the twentieth century, research advances caused a substantial decline in the rate of coronary heart disease. The decline lasted from the mid-1960s until the early 1990s and occurred primarily in Western countries. However, an unfavourable trend in coronary heart disease related mortality has gradually developed during the 1990s, with cardiovascular diseases anticipated to remain the main cause of overall mortality for the foreseeable future. The present paper aims at analyzing the current status of the main determinants of population-wide coronary heart disease prevention.

Design of a randomized controlled trial of comprehensive rehabilitation in patients with myocardial infarction, stabilized acute coronary syndrome, percutaneous transluminal coronary angioplasty or coronary artery bypass grafting: Akershus Comprehensive Cardiac Rehabilitation Trial (the CORE Study)

OBJECTIVES: 1. To assess the long-term effectiveness of a comprehensive cardiac rehabilitation programme on quality of life and survival in patients with a large spectrum of cardiovascular diseases (myocardial infarction, acute coronary syndrome, percutaneous transluminal coronary angioplasty and coronary artery bypass grafting). 2. To establish the degree of correlation between expected improvement of health-related quality of life and improvement in physical function attributable to rehabilitation in the intervention group, in comparison with similar changes in the conventional care group. DESIGN: Randomized, controlled, parallel-group design (intervention/conventional care). SETTING: Akershus County, southeast of Oslo City, Norway. PARTICIPANTS: 500 patients, men and women, aged 40-85 years, who have sustained at least one of the above-mentioned cardiovascular diseases. INTERVENTIONS: 8 weeks of supervised, structured physical training of three periods of 20 min per week, targeting a heart rate of 60-70% of the individual's maximum; home-based physical exercise training with the same basic schedule as in the supervised period; quantification of patients' compliance with the exercise programme by the use of wristwatches, information stored in the watch memory being retrieved once a month during the 3-year follow-up period; and life-style modification with an emphasis on the cessation of smoking and on healthy nutrition and weight control.