Calls this week for school lunch boxes to be produced in uniform drab brown colours to make them less attractive to children are being considered by the Government.
Campaigners have long argued that the contents of the school lunch box is harmful and that junk food and indequate nutrition contribute to the growing problem of childhood obesity rates and poor results in numeracy and literacy. One pressure group said: "We know that children become addicted to packed lunches at a young age. This is a major public health issue and action needs to be taken now." Recent research has shown that what you eat for your lunch as a child determines your food choices for the rest of your life. You only have to see how popular sandwiches and fizzy drinks are amongst adults. It can all be traced back to the school packed lunch. In Australia the government took the brave step of legislating to make lunch boxes have plain covers with standardised health messages on the outside. "These images are graphic and, we make no apologies for that," said a Ministry of Health official. "they're designed to put children off their lunch." Whilst the scientific evidence behind this move isn't strong at the moment, time will prove that we were right said a government spokesman. Other groups have called for a complete ban on the school packed lunch. This is a national emergency, if we can't have these packed lunches banned we need skilled staff to inspect school lunch boxes. Claims that one school was considering airport style security measures to scan lunch boxes at the school gate and to restrict juice containers to less than 100ml have been strongly denied. In other news the Government has shelved plans for minimum pricing on alcohol and plain packaging for cigarettes saying they would rather concentrate on issues that will really impact on public health.
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The first coronary stent was implanted in 1986 by Dr Ulrich Sigwart. Stents are metal scaffolds which have revolutionised coronary angioplasty. Prior to stents, coronary dissection, caused by balloon angioplasty, usually resulted in an emergency coronary bypass operation or at best a 90% stenosis was reduced to a 40% one. Stents solved these problems but led to different ones. First there was stent thrombosis. Patients were initially treated with aspirin and warfarin to inhibit the clotting pathways but the bleeding problems were terrible. Then we then realised that aspirin could be combined with ticlopidine and subsequently clopidogrel to provide a safe treatment to reduce stent thrombosis but without the bleeding. Then there was the problem of restenosis (re-narrowing) at the site of the coronary stent implant. This led to spot stenting to keep the length of stent as short as possible. After that and thanks to Antonio Colombo and the use of intra-vascular ultrasound we realised that stents needed to be implanted at high to reduce restenosis. However problems with restenosis still existed and cardiologists developed complex treatments such as brachytherapy (intra-arterial radiotherapy) which now have all but disappeared. In the early 2000's we were introduced to the drug eluting stent. First Cypher, then Taxus and then the second generation stents such as Xience, Promus and Integrity Resolute. No longer did interventional cardiologists have to worry about the length of stent they were implanting. Treat from normal vessel to normal vessel became the mantra. But the downside was stent thrombosis, originally thought to just be a short term problem it is clear that it could occur years after stent implantation. Also in some high risk patients such as those with diabetes the restenosis problem has not been completely solved. There are some patients with in-stent, in-stent re-stenosis for which the treatment options are limited. The holy grail of stenting has been seen as the biodegradable or resorbable stent. Implant the stent when it is needed for the first few months and then when it has done its job, like a self absorbing suture, it dissolves away. This sounds an attractive prospect and in 2012 the world of stenting was revolutionised by the entry of the first commercially available biodegradable stent called ABSORB. In the early phase after implantation the ABSORB revascularises like a drug eluting stent. It releases the anti-proliferative drug everolimus to minimise neo-intimal growth and restenosis. During the restoration the scaffold benignly resorbs and the stent gradually ceases to provide luminal support resulting in a discontinuous structure embedded within the coronary artery. As the scaffold degrades, the polymer is converted into lactic acid which is metabolised and is ultimately converted into benign by-products of carbon dioxide and water. Several studies support this concept and indicate that there is no clinical benefit of a permanent stent over time. The ABSORB eliminates the permanent mechanical restraint on the vessel and should allow for more normal blood vessel function. Three-year results from 101 patients in the second stage of the ABSORB trial have shown that the rate of major adverse cardiovascular events was 10% at three years, similar to a comparative set of data with a best-in-class drug eluting stent at the same follow-up period. In a subset of 45 patients, intravascular imaging techniques showed improvements in vessel movement and a 7.2% increase in late lumen gain (an increase in the area within the blood vessel) from measurements taken at one and three years. These findings are unique to the absorbable stent and are not typically observed with metallic stents that cage the vessel. The ABSORB stent is now available and patients interested in receiving it should discuss with their cardiologist to see if they are suitable for the device. References: ABSORB II Trial ABSORB-Extend Trial
The data on angioplasty in the UK is out this week on the BCIS website and it appears that all 557 cardiologists whose data is reported have a MACCE (major adverse cardiac and cerebrovascular event) rate within that expected. MACCE is a measure of the number of patients who died, had a stroke or needed an emergency bypass operation after an angioplasty procedure. BCIS estimate the MACCE rate for each patient based on parameters which are reported in a study from data obtained some 10 years ago called NWQIP. This model predicts, apparently, with 70% accuracy according to the patient's age, sex, emergent PCI, urgency of treatment, cardiogenic shock and whether a bypass graft or the left main stem was intervened on. From this BCIS estimate the 95% confidence intervals (CI) of the predicted MACCE and provided the cardiologists actual MACCE rate is lower than the upper CI then everything is apparently fine. So statistically if there were 1000 cardiologists you would expect that by chance alone then 25 of them would be above the upper 95% confidence interval and 25 would lie below the lower confidence interval. So what is the chance that not one of the 557 cardiologists in the BCIS report would be outside the top 95% confidence interval? Well its a very small number (actually p=0.000000751). So currently this is an exam which a cardiologist has a 1 in 100 million chance of failing. Now as BCIS say you can't directly compared different operators but what you can do is look at people who have a similar practice. If you pool data from cardiologists who do more than 75 angioplasty procedures per year (the BCIS recommended minimum) and who do more than 10 primary PCI procedures (treating patients with acute heart attacks who are the sickest patients) then the average MACCE rate is 2.2%. This is much lower than 8.2% MACCE rate which is predicted by the BCIS model. Although we might like to regard interventional cardiologists are superhuman creatures what this data really tells us is that the model BCIS has used to predict risk vastly over predicts the actual MACCE making this truly an exam which cannot be failed. To be fair BCIS do acknowledge the limitations of the data but there is an urgent need for more contemporary risk prediction models going forward. The release of the surgical outcomes data last Friday was like a firework. There was a loud bang and a brief flash when people looked and then it disappeared into the darkness. In fact the story was more about the data that wasn't released than the data that was. Surgeons who defied the call for their data to be published were looked on with suspicion and outed at the behest of Jeremy Hunt, the Health Secretary. Once upon a time the only thing people talked about when it came to the assessment of quality in angioplasty was the number of procedures performed with high volume operators and centres regarded as the best. Part of this was because procedural volume was easy to measure whilst other quality markers were not. Today sees the publication of the coronary angioplasty data which has been collated by the British Cardiovascular Intervention Society (BCIS). The society has been collecting data on angioplasty since 1992 and presenting it as an annual audit on their website. In 2012 it became possible to link an individual angioplasty procedure to the GMC number of the consultant responsible and hence to produce the operator level data which has been published today. BCIS has tried to not turn this a beauty contest between interventional cardiologists and they have made it difficult, but not impossible, to compare the data. They rightly state that it is not possible to compare different cardiologist and this is true since the case mix of one will be different from another. There are some cardiologists who only perform only elective angioplasty on stable angina patients or who work in hospitals that don't perform primary angioplasty for acute heart attacks. These cardiologists should have very low death rates. BCIS have used a measure of self reported in-hospital death rate, stroke rate and requirement for emergency bypass surgery. From this they calculate a MACCE (major adverse cardiac and cerebrovascular event) rate for each interventional cardiologist. Then they calculate an expected MACCE rate and its 95% confidence interval based on patient factors including age, sex, history of stroke, urgency of procedure using a model developed by the North West Quality Improvement study (NWQIP). In a nutshell provided the cardiologist's MACCE rate is less than the 95% confidence interval then they are not regarded as an "outlier" and their practice is regarded as safe. So what determines MACCE? It is dependent on patient, interventional cardiologist and post-procedure factors. In most cases death, stroke and need for emergency bypass surgery are more dependent on the type of presentation, co-morbidity of the patient and severity of the coronary artery disease. The skill of the cardiologist might be better judged in terms of procedural complications such as vascular access site bleeding, the need for urgent repeat coronary intervention, the number of acute stent thrombosis or stent restenosis. These measures whilst more difficult to collect would provide a better estimate of quality. Measuring survival to hospital discharge as an outcome also leads to anomalies. Take this scenario, Cardiologist A treats an elective, stable patient with a stent and the patient is discharged only to be readmitted 48h later with an acute stent thrombosis causing an acute heart attack. This rare complication can sometimes be caused because of stent under-deployment. Cardiologist B is on call and treats the patient in the catheter lab to salvage the acutely blocked artery but sadly the patient dies. In the current analysis this death is recorded as belonging to Cardiologist B not Cardiologist A. A move to the measurement of 30 day mortality is needed but there will be difficulties in apportioning deaths when two cardiologists have treated the same patients. Another important skill, which is very difficult to measure, is that of case selection. Some cardiologists will attempt emergency angioplasty on almost all patients presenting with an acute myocardial infarction even if the chance of survival is very low. With the publication of this data it is likely that cardiologists will start to think twice before taking such patients to the catheter lab where the procedure may be futile, the outcome inevitable and the death counted on their angioplasty statistics. Interventional cardiologists have often been put in a position where an emergency patient has been turned down by a cardiothoracic surgeon because the risk of operation is deemed to high risk and they have then gone on to offer angioplasty. This behaviour may well change as interventional cardiologists are subject to increasing scrutiny. The other issue is training the next generation of interventional cardiologists. If the consultant is responsible for the procedure and the data is going to be published in a public forum how comfortable will they be allowing a fellow or registrar to be the first operator in a difficult case. If a mistake is made by the trainee cardiologist during the procedure this could affect the outcome. On the other hand if we don't train the interventional cardiologists of the future what hope will there be for us when we are old and need intervention ourselves. So what of the data released today. First we have to accept that some of it is missing as not all hospitals contributed so any conclusion drawn here are based on the data that is available. In 2012, 559 consultant cardiologists performed 83,121 angioplasty procedures. There were 22,426 primary angioplasties performed to treat acute ST elevation myocardial infarctions, 30,399 to treat acute coronary syndromes and 27,860 to treat stable angina. the rest were coded as other or unknown. The majority of angioplasty in the UK is used to treat emergency patients with only 34% of procedures for stable angina. This is very different from the data from other reports such as the New York State where 83% of PCI procedures were done for stable angina. Some hospitals perform a very large number of procedures. For example Liverpool Heart and Chest performed 2929 with the Freeman in Newcastle coming a close second with 2832 procedures. At the other end of the spectrum are the private hospitals which tend to perform mainly elective PCI usually, though not exclusively, by cardiologists who also work in NHS hospitals as well. Hospitals are supposed to perform 250 cases per year to remain viable, 17 hospitals reported completing less procedures than this. What can we learn from the individual data? BCIS have been careful to present the data in a way in which makes the comparison of different cardiologists very difficult. Each operator's data is presented separately on an individual webpage and so to make any direct comparison laborious. I suspect this was a deliberate measure but it does not make it impossible to abstract the data and to look at differences. Most surprisingly they also do not separate the outcome data into elective and non-elective cases. It is obvious that the MACCE rate for elective angioplasty will be low. Currently patients are quoted a 1% chance of heart attack, stroke, death or need for emergency bypass surgery when they sign the consent form. The actual MACCE rate for this procedure is probably around 0.2%. Compare this to the MACCE rate of more than 50% for a patient presenting with an acute myocardial infarction, cardiogenic shock and following an out of hospital cardiac arrest. No cardiologist had MACCE rate greater 95% of predicted so it appears that everyone is operating within the expect levels. I suspect this reflects the crude nature of the MACCE measurement and the NWQIP model which has been used. Looking at the high volume operators the predicted MACCE rates is running about twice as high as the actual MACCE rate suggesting that it does not predict particularly accurately a contemporary patient population. Statistically out of 559 operators one might expect at least 25 to lie above the 95% confidence interval simply by chance alone - none do, again questioning the accuracy of the risk prediction model and any conclusions regarding safety are dubious. BCIS recommend that interventional cardiologists should perform at least 75 PCI procedures per year in order to maintain competence. Nearly 20% of operators are apparently performing less than this with many of the interventional cardiologists working solely in the private sector doing very small numbers of cases each year. The median number of procedures per cardiologist is 138 although there are some cardiologists performing significantly larger numbers of procedures. Some cardiologists MACCE rates fall very close to the 95% confidence limit and some very far away. For example the largest volume operator in the UK who did 591 cases has a MACCE rate of only 0.17% (95% CI: 3.12%) although 62% of his patients were elective and only 5% primary PCI cases. At the other end of the procedural volume spectrum there is great difficulty in analysing data because of the small numbers. When a cardiologist has done only 25 procedures the confidence interval is so wide as to preclude any meaningful analysis. The publication of the angioplasty data by BCIS is a step in the right direction. Hopefully it will lead to an improvement in the quality of data collection and accuracy. What is sorely needed is the development of more accurate risk and quality control models as well as moving to measurement of 30 day mortality. We are at the beginning of a long and interesting journey and at the end we will see that quality in angioplasty is more than procedural volume. References: Grayson AD, Moore RK, Jackson M, et al. Multivariate prediction of major adverse cardiac events after 9914 percutaneous coronary interventions in the north west of England. Heart 2006 May;92(5):658-63. BCIS Individual Operator Level Data Website PCI in New York State Report 2008-2010 |
Dr Richard BogleThe opinions expressed in this blog are strictly those of the author and should not be construed as the opinion or policy of my employers nor recommendations for your care or anyone else's. Always seek professional guidance instead. Archives
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