Finding the forest through the trees in statistics: let the Statistical Primers in EJCTS/ICVTS guide you

Evidence-based medicine is the cornerstone of modern medicine. With increasing regulations from governments and insurance companies, the need to provide and continuously improve the quality of care is one of the duties of a physician practicing in the 21st century. Advances in our understanding of the human body and the technology we use to diagnose and treat patients has, through greater understanding, led us to an era in which we can no longer practice ‘what we believe in’ but have to practice based on evidence. Clinical guidelines committees should ideally include physicians with experience in producing and interpreting evidence from clinical studies in combination with methodologists [1]. Consequently, these guidelines will provide important evidence-based answers to different clinical questions for a large readership, meaning that individual physicians do not have to engage in such a complex task. However, guidelines often provide broad recommendations to guide decision-making yet lack nuances that physicians encounter in everyday practice. While many physicians acknowledge the need to use clinical guidelines for decision-making, one important aspect is often forgotten: physicians can provide evidence-based care only if they have at least a basic knowledge of statistics to interpret and judge the evidence. But is the subject of statistics really crucial in our work as physicians? Learning how to do a coronary artery bypass graft procedure, a video-assisted thoracoscopic surgery lobectomy or a valvesparing aortic root replacement require many hours of training. So should we distract ourselves occasionally and move from the operating room to a statistics course? The answer is simple: yes, we should. Despite general negligence towards statistics, evidence suggests that 97% of physicians agree that statistics is useful in everyday clinical work [2]. More importantly, 63% of physicians agree that their clinical practice could improve if they had better statistical knowledge on, for example, not only critically evaluating clinical research and understanding the risks but also elaborating on treatments to other physicians and patients. Ironically, there is enough evidence to support the statement that physicians do not understand basic statistics [3]. A number of studies have shown that physicians in different countries fail to answer the majority of basic statistical questions [3–6]. In a survey of 277 internal medicine residents out of 11 residency programmes in the USA, Windish et al. [7] found that residents answered correctly a mean of 41.5% of 20 questions on the statistical knowledge and interpretation of results. Remarkably, only 10.5% could correctly interpret a Kaplan–Meier analysis, only 11.9% could interpret 95% confidence intervals and statistical significance and only 37.4% could interpret an odds ratio from a multivariable regression analysis; the cardiothoracic and vascular surgery literature is largely based on such analyses. Organizations such as the General Medical Council in the UK as well as the World Health Organization have recommended including statistics in medical education [3]. However, even though statistics is being taught at most medical schools around the world, one of the reasons for the lack of statistical knowledge is that many of these courses are relatively short as opposed to clinical courses and basic in comparison with what is needed to adequately perform clinical research and interpret evidence. Indeed, if previous training or coursework in biostatistics was performed, the mean score on the statistical knowledge and interpretation of results increased only modestly from 37.9% to 45.2% in the study by Windish et al. [7] (P = 0.001), even though these questions included basic statistical knowledge. With the increasing use of complex statistical methods [8] that are mystifying even for advanced statisticians [9], we risk generating a huge gap between the medical literature and clinical practice [10]. But it is never too late to learn. The European Association for Cardio-Thoracic Surgery (EACTS) has recognized the need for education among its members and have appropriately adopted the slogan ‘Raising Standards Through Education and Training’. Naturally, this includes continuous improvements in surgical skills, but we should not forget that techniques in the operating theatre have often been extensively studied using statistics. The EACTS has therefore embraced more statistical education, ED IT O R IA L