tag:blogger.com,1999:blog-6193043695356712843.post7670219314987569401..comments2023-09-02T23:55:45.583+10:00Comments on Doctor Skeptic: Stop attacking my heartDr Skeptichttp://www.blogger.com/profile/09376469049519802493noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-6193043695356712843.post-86690481749852476482016-05-20T10:35:06.188+10:002016-05-20T10:35:06.188+10:00One of the first randomized studies that compared ...One of the first randomized studies that compared medical therapy alone with coronary bypass surgery in stable CAD patients was the Coronary Artery Surgery Study (CASS) trial, published in 1983. In this study, 780 CAD patients were randomized to one of the two strategies and followed for 5 years. Interestingly, in this study, the average annual mortality rate for patients assigned to medical therapy was 1.6% and to surgery 1.1% (P = 0.34). Analyzing only the patients with an ejection fraction ≥ 0.50 (75% of the entire population of the trial), those assigned to medical therapy had annual mortality rates of 1.1%, 0.6%, and 1.2%, respectively, for single-, double-, and triple-vessel disease. Patients with an ejection fraction ≥ 0.50 assigned to surgery had similar mortality rates 0.8%, 0.8%, and 1.2%, respectively, for single-, double-, and triple-vessel disease. There were no statistical differences between the two treatment strategies.Anonymoushttps://www.blogger.com/profile/12796245218427012668noreply@blogger.comtag:blogger.com,1999:blog-6193043695356712843.post-50786794772988115762012-07-25T19:51:18.426+10:002012-07-25T19:51:18.426+10:00Thanks Anon,
Thanks for the link. Agree with confo...Thanks Anon,<br />Thanks for the link. Agree with confounding issues, as that study is observational. Timing issues have been addressed in other areas and can be a bit confusing (in establishing cause and effect), and associations seen in observational studies can disappear on adjusted analyses or later randomised trials.Dr Skeptichttps://www.blogger.com/profile/09376469049519802493noreply@blogger.comtag:blogger.com,1999:blog-6193043695356712843.post-73478757122508397132012-07-25T05:56:36.537+10:002012-07-25T05:56:36.537+10:00There is pretty good evidence, however, that doing...There is pretty good evidence, however, that doing a PCI early is better than doing one late: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2095752/<br /><br />(Of course, there's also a host of potential confounders around the circumstances under which one might be done early or late, e.g. general quality of care).Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6193043695356712843.post-37518935308406476202012-07-10T23:01:13.133+10:002012-07-10T23:01:13.133+10:00Thanks Secuti, and this problem is particularly no...Thanks Secuti, and this problem is particularly noticeable in conditions affecting older people, like interventions to reduce mortality in hip fracture patients, as the average age is 80 and the 12 month mortality is about 25%. Disease specific mortality is, well, more specific, but overall mortality is more important, and can uncover harms from the interventions.<br />Your comment highlights another one of my recurring points, that the perception of benefit from interventions is much greater than the reality. Many people think that cancer treatments and screening and stents save lives - that if you are still alive one year later, it is due to the intervention, and that you would not be alive unless you had received the treatment.Dr Skeptichttps://www.blogger.com/profile/09376469049519802493noreply@blogger.comtag:blogger.com,1999:blog-6193043695356712843.post-81786906659967783992012-07-10T22:05:35.725+10:002012-07-10T22:05:35.725+10:00I think one possible explanation for the failure t...I think one possible explanation for the failure to reduce overall mortality in so many of these disparate studies (cardiovascular, oncology etc.) is that death is an overdetermined variable. There are many possible causes of death all competing with each other with an overall probability that rises with age, eventually exceding 1.0.<br /><br />Lets say a patients additive mortality probability is 1.2 over 10 years of which cardiac causes contribute 0.5. Reducing the later by 40% with some intervention still leaves a probability of death at 1.0 at 10 years ie besides 'benefiting' the patient will still die.<br /> This principle also explains why, even if all cancers were to be cured overnight, the breakthrough would add only 3-4 years to average life expectancy.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6193043695356712843.post-13270598518991851452012-07-10T00:25:40.771+10:002012-07-10T00:25:40.771+10:00Thanks for providing a patient perspective, and I ...Thanks for providing a patient perspective, and I understand the important role of peace of mind, but I am not talking about being hit by a bus, I am talking about mortality associated with the intervention.<br />A good example is breast cancer screening, where large randomised studies of mammography (over 600,000 women) have shown a significant reduction in breast cancer mortality, but because the overall mortality is the same, it means that those who underwent mammography were more likely to die of other causes. There was real harm for the thousands of women who had false positive diagnoses and subsequently underwent surgery, radiotherapy, chemotherapy etc.<br />I do not want to ignore the reduction in cardiovascular death, but I still think that what epidemiologists call 'fact of death' trumps 'cause of death' every time.Dr Skeptichttps://www.blogger.com/profile/09376469049519802493noreply@blogger.comtag:blogger.com,1999:blog-6193043695356712843.post-77654436910424401112012-07-09T23:54:50.320+10:002012-07-09T23:54:50.320+10:00"I always look at overall mortality in studie..."I always look at overall mortality in studies of treatments that are meant to reduce mortality." <br /><br />That's because you've likely never survived a heart attack.<br /><br />Those who do, trust me on this, are VERY interested in future CV death and MI risks. True, I could get hit by a bus tomorrow or develop a brain tumour or die of sepsis after a botched knee surgery, but my odds of having a subsequent MI are what actually keep me awake at night. . .Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6193043695356712843.post-40105148061273262022012-07-09T01:45:41.452+10:002012-07-09T01:45:41.452+10:00Thanks CZ,
The conclusion you refer to is correct,...Thanks CZ,<br />The conclusion you refer to is correct, but my question is: Is that the conclusion you are interested in? Despite the reduction in CARDIOVASCULAR death or MI in high risk patients, there was still no significant difference in the OVERALL deaths.<br />This is a common finding in many studies. For example, cancer studies talk about disease-specific mortality often being reduced with treatment X, but overall mortality is often the same.<br />I always look at overall mortality in studies of treatments that are meant to reduce mortality. Measures of subgroup mortality can be spurious.Dr Skeptichttps://www.blogger.com/profile/09376469049519802493noreply@blogger.comtag:blogger.com,1999:blog-6193043695356712843.post-3115937771634930782012-07-09T01:19:06.876+10:002012-07-09T01:19:06.876+10:00Hi Dr. S - as a heart attack survivor, I too am co...Hi Dr. S - as a heart attack survivor, I too am concerned about the "stent happy" cardiologist like Mark Midei et al whose overuse of this expensive treatment option has given stents a black eye (and interventionalists big headaches!) <br /><br />But a slight addition to your post is in order here: the 2010 J Am Coll Cardiology review you mention in fact concluded: <br /><br />"Routine invasive strategy reduces long-term rates of cardiovascular death or MI and the largest absolute effect in seen in higher-risk patients." <br /><br />This is an important difference for those of us high-risk patients who survived ACS/MI and were subsequently stented.Anonymousnoreply@blogger.com