Statistical primer: using prognostic models to predict the future: what cardiothoracic surgery can learn from Strictly Come Dancing.

OBJECTIVES: Prognostic models are widely used across medicine and within cardiothoracic surgery, where predictive tools such as EuroSCORE are commonplace. Such models are a useful component of clinical assessment but may be misapplied. In this article, we demonstrate some of the major issues with risk scores by using the popular BBC television programme Strictly Come Dancing (known as Dancing with the Stars in many other countries) as an example. METHODS: We generated a multivariable prognostic model using data from the then-completed 19 series of Strictly Come Dancing to predict prospectively the results of the 20th series. RESULTS: The initial model based solely on demographic data was limited in its predictive value (0.25, 0.22; R2 and Spearman's rank correlation, respectively) but was substantially improved following the introduction of early judges' scores deemed representative of whether contestants could actually dance (0.40, 0.30). We then utilize our model to discuss the difficulties and pitfalls in using and interpreting prognostic models in cardiothoracic surgery and beyond, particularly where these do not adequately capture potentially important prognostic information. CONCLUSION: Researchers and clinicians alike should use prognostic models cautiously and not extrapolate conclusions from demographic data alone.

Differential effects of high-altitude exposure on markers of oxidative stress, antioxidant capacity, and iron profiles.

High-altitude (HA) exposure may stimulate significant physiological and molecular changes, resulting in HA-related illnesses. HA may impact oxidative stress, antioxidant capacity, and iron homeostasis, yet it is unclear how both repeated exposure and HA acclimatization may modulate such effects. Therefore, we assessed the effects of weeklong repeated daily HA exposure (2,900-5,050 m) in altitude-naïve individuals (n = 21 individuals, 13 females, mean ± SD, 25.3 ± 3.7 yr) to mirror the working schedule of HA workers (n = 19 individuals, all males, 41.1 ± 9.4 yr) at the Atacama Large Millimeter Array (ALMA) Observatory (San Pedro de Atacama, Chile). Markers of oxidative stress, antioxidant capacity, and iron homeostasis were measured in blood plasma. Levels of protein oxidation (P < 0.001) and catalase activity (P = 0.023) increased and serum iron (P < 0.001), serum ferritin (P < 0.001), and transferrin saturation (P < 0.001) levels decreased with HA exposure in both groups. HA workers had lower levels of oxidative stress, and higher levels of antioxidant capacity, iron supply, and hemoglobin concentration as compared with altitude-naïve individuals. On a second week of daily HA exposure, changes in levels of protein oxidation, glutathione peroxidase, and nitric oxide metabolites were lower as compared with the first week in altitude-naïve individuals. These results indicate that repeated exposure to HA may significantly alter oxidative stress and iron homeostasis, and the degree of such changes may be dependent on if HA is visited naïvely or routinely. Further studies are required to fully elucidate differences in HA-induced changes in oxidative stress and iron homeostasis profiles among visitors of HA.

Do medical students studying in the United Kingdom have an adequate factual knowledge of basic life support?

BACKGROUND: Healthcare professionals have a duty to maintain basic life support (BLS) skills. This study aims to evaluate medical students' factual knowledge of BLS and the training they receive. METHODS: A cross-sectional, closed-response questionnaire was distributed to the first- and fourth-year students studying at institutions in the United Kingdom. The paper questionnaire sought to quantify respondent's previous BLS training, factual knowledge of the BLS algorithm using five multiple choice questions (MCQs), and valuate their desire for further BLS training. Students received 1 point for each correctly identified answer to the 5 MCQ's. RESULTS: A total of 3,732 complete responses were received from 21 medical schools. Eighty percent (n=2,999) of students completed a BLS course as part of their undergraduate medical studies. There was a significant difference (P<0.001) in the percentage of the fourth-year students selecting the correct answer in all the MCQ's compared to the first-year students except in identifying the correct depth of compressions required during CPR (P=0.095). Overall 10.3% (95% CI 9.9% to 10.7%) of respondents correctly identified the answer to 5 MCQ's on BLS 9% of the first-year students (n=194) and 12% of the fourth-year students (n=190). On an institutional level the proportion of students answering all MCQ's correctly ranged from 2% to 54% at different universities. Eighty-one percent of students (n=3,031) wished for more BLS training in their curriculum. CONCLUSION: Factual knowledge of BLS is poor among medical students in the UK. There is a disparity in standards of knowledge across institutions and respondents indicating that they would like more training.

The potential role of external venous supports in coronary artery bypass graft surgery.

Despite the apparent superiority of arterial conduits for coronary artery bypass grafting (CABG), the long saphenous vein remains the most commonly used graft. The high failure rate of long saphenous vein grafts (SVGs) over time is therefore an important limiting factor for the long-term outcomes of CABG. Various methods to improve SVG patency have been proposed, although few have had a significant impact on clinical practice. External SVG supports have been a focus of research over the past 50 years, with their use intended to minimize well-documented pathophysiological changes that occur in the SVG following implantation into the coronary circulation. These devices have been trialled extensively in animal models to assess their impact on both the morphology and the function of vascular conduits. Recently, a number of studies have been conducted in patients, leading to a substantial development in their design and the accumulation of a large body of evidence attesting to their potential benefit in CABG. In this review, we briefly discuss the proposed mechanism of action of external SVG supports and then evaluate the results from animal studies and more recent research assessing their use in CABG patients. Finally, we conclude that newer models of external stents have the potential to improve long-term outcomes in SVG.

Does Previous Transradial Catheterization Preclude Use of the Radial Artery as a Conduit in Coronary Artery Bypass Surgery?

The radial artery (RA) is a commonly used conduit for coronary artery bypass grafting, and recent studies have demonstrated that it provides superior long-term patency rates to the saphenous vein in most situations. In addition, the RA is also being used with increasing frequency as the access point for coronary angiography and percutaneous coronary interventions. However, there has been concern for many years that these transradial procedures may have a detrimental impact on the function of RA grafts used in coronary artery bypass grafting, and there is now comprehensive evidence that such interventions cause morphologic and functional damage to the artery in situ. Despite this, there remain remarkably few studies investigating the use of previously cannulated RAs as grafts in coronary artery bypass surgery, and there are no clear guidelines on the use of the RA in coronary artery bypass grafting after its catheterization. This article will review concisely the evidence that transradial procedures cause damage to the RA, and discuss the impact this could have on previously cannulated RAs used as coronary artery bypass grafting conduits. On the basis of the evidence assessed, we make a number of recommendations to both surgeons and cardiologists regarding use of the RA in cardiovascular procedures.