Computer generated transcript

Warning!
The following transcript was generated automatically from the content and has not been checked or corrected manually.

which is a bit, which is an important, um, public health concept. Um, I have got slump, some slides to talk to you about. I'm hoping that Claudia would be able to load them up, sort of. Or if I can launch the, um, meeting from my, um, from my laptop, then I can show it to you. But, uh, Claudia, I just forwarded the email back to you again. Yes, I have literally just received it. Now I will share screen. Thank you. Thank you very much. So sorry, guys. Um, 10 minutes gone, but we'll rush through a bit of a presentation. Um, and then, um and then we'll we'll get going. So sorry about the delay. Um, Okay. So, um, as I said, today's talk is about, uh, screening programs. Um, in the United Kingdom, we have, um and you can see that this was produced by one of our public health registrars. So, um, a big thank you for them to share their slides with May. So, um, I have kept, um and acknowledge them on on the slides. Um, so this is an introduction to screening program. So objective of the section next slide, please. um is to teach you, uh, talk to you about, um, keep going and keep clicking for me, please. Claudia, thank you. Understanding the key concepts and key issues around screening, understanding how communication affects understanding of the principles of screening critically assess whether a condition is suitable for a clinical screening program. So what is screening? So next? Likely so screening is a public health service. And, um, you would have different screening programs in, um in Ukraine or any other part of the world that you're going to be practicing in, Um, and it is a public health service, which members of a defined population who do not necessarily perceive that they're at risk of or already affected by disease are asked a question or offered a test to identify those individuals who are more likely to be helped than harmed by further tests or treatment to reduce the risk of a disease or its complications. Now that's a bit of a worthy definition, and we in in the United Kingdom. We've got a national screening committee, which tells us which undergoes a lot of evidence and review and research to understand what, um, tools or tests can become screening, Um, tools. Um and that is quite important, because, um, there are lots of tests. Who can, which you know which people might think. Why don't we have a screening? Um, tool force a prostate cancer or ovarian cancer? Um, but the screening tools or the tests that are available, um, may cause more harm, um, than identify disease early. So therefore, um, uh, screening tests or tools are put into place because you're basically screening healthy people. So people who are not affected by the disease So they have to be carefully, um, thought about and there's a lot of evidence and research goes in before they are identified as a screening tool or a test next slide, please. So what is the purpose of screening? So the purpose of screening is that we reduce morbidity and mortality. Um, and, uh, we we, um uh, kind of have an earlier, um, way of identifying, um, a stage of a disease when it's early, so that we can make amends and make treatment plans in Sometimes the screening tests are helping to inform decisions about the person's own health or the future of a child health. And there's a human rights approach to it. So we do. Antenatal screening antenatal helps to identify. Um uh, if Children people have certain, um, congenital abnormalities early Now there's a human right and ethical risk there because, um, you might think that technology so advanced that people with some congenital abnormality slides such as down syndrome live a productive life till quite late age. So do we need to screen them early? Um, and yes, of course, the discussion can happen. Um, parents can choose not to screen, but if they choose to screen, then they can know. Um, they can have that ethical, um, conversation right up front to say whether they want to then continue forward with with with the pregnancy. So screening tool helps us with that as well. Um, and and then when apply to conditions like dementia, you can you can give some screening questionnaires, which might help you to identify whether there's early signs of dementia. But then how do we then treat that? So all of those discussions come into play in kinds of screening programs and tools. Next, like please. So what are the aims of screening? So the aims of screening is to identify a condition otherwise unknown before it clinically manifest itself. Uh, then we can intervene and improve the outcomes. And in many ways, it can sometimes protect society from contagious diseases as well. So some certain screening tools can also do that to next slide, please. As opposed to case finding case finding is secondary prevention through early detection of cases using health services for other reasons. So, for example, if you wanted to find out if you have got, um, people with diabetes who have not been diagnosed then in a in a community set up, you could run some programs of work where you could do, um, you know, get them to come in and have an assessment and have have a finger prick test to, uh, identify if they've got early diagnosis. So they've already got diagnosis. They don't know they've got diagnosis, but we can do tests, uh, and then find out that they they've got diagnosis. So that's kind of early case finding. And it's not screening because in this case, uh, in in the screening, we're looking at people who are healthy and don't have any clinical conditions, and in case finding they have a condition they don't know about it. And, um, they will identify. Um, you know, a test will identify whether they've got the disease or not. We can still identify them early and give them treatment regimes that can help them next. Like please. Um so So therefore, that's exactly what I'm saying. So screening versus case finding screening is directed at people who do not have symptomatic disease, and case finding is directed at people who have presented, um to the health service and are usually unhealthy in some kind of way. So if you were to screen obese people, um, and then if you offered them a blood test, you might be able to find a lot of people who've got undiagnosed Type two diabetes. And that's case finding. And it's not a screening program. Um, next, like please. So why stress the difference? Because, um, it's different from clinical practice and targets, apparently healthy people. So that's what we're kind of still trying to hone in on the fact that screening programs are for healthy people, um, and population properly organized screening programs, um, can add that, uh, it's not a marginal extra two. A clinical service. Um, and it has to be done properly as a program. So you can't say Okay, Come on. Diabete service. You need to go and identify all the people with undiagnosed diabetes. So can you just do something on top and go and and, uh, you know, give a blood test to everybody who's over bm i 30 And then you diagnose more diabetes people that can be done for a screening program. A screening program has to be set about how we go out and ask people who are otherwise healthy in a particular age group to come forward and have a test or have a screening tool which identifies a clinical condition for them. So next slide, please. So in the United Kingdom, we have, um uh, so, uh, yeah. Sorry. Take that out. Take that in the next one, please. Yeah, the next one, please. Thank you. If you go to the next slide, please. Thank you. Yeah. And click again. Yeah. So this one. So in the United Kingdom, um, uh, this is the list of all of the, um screening programs that are available off by the general population. So, as you can see, there is antenatal screening programs and that pick up fetal anomaly. There's infectious diseases also screened for pregnant women are screened for HIV, hep B, rubella and syphilis. That's an initial blood test. As soon as you become pregnant, you can do, uh, do that blood test and women who are at high risk and also screen uh, screened for sickle cell and thalassaemia. Because those are also important in pregnancy to, uh, to identify early in the newborn, um, in the newborn, uh, stage, there is, uh, the newborn and infant physical examination, which helps to identify, uh, the any problems with the with the newborn child. There's a newborn blood spot test, which helps to identify if they've got thyroid or other metabolic conditions. And then there's a newborn hearing test in Young Person's uh, and an adult. We've got screening test for abdominal aortic aneurysm, diabetic retinopathy, breast cancer, cervical cancer, bowel cancer and then the other related programs not quite made into the screening program. So there's pros post prostate cancer risk management, this chlamydia screening in young people, and there's NHS Health Checks Program, which is to identify people with high risk of vascular conditions next slide, please. So what do we need to know before we set up a screening program? Okay, so So the next likely will take us through some of the concepts. So as you can see on here, So if you start from the from the left hand side, we're picking up healthy people who've got no detectable disease, Okay? And then before they develop a detectable disease, so so please note the time interval, So t zero is when they don't have a disease. T two is when we are screening them for the disease, and t one is where they've got a clinically detectable disease. So for the purpose of understanding this, let's just focus on t zero and t one. Okay, So what? We're trying to know what we know from pathophysiology of conditions. So for cervical cancer, breast cancer and some of these cancer programs that there is a lead time before and and there's a huge on time. So, John time is a time before they healthy person goes and develops breast cancer. Say, for example, what we know from the evidence and research is if we intervene in that soldier on time, so as you can see in the middle of the of the slide. It says so John Time. So John time safe for breast cancer is from the time that person is healthy to the time that they develop full blown breast cancer. Now, if in that soldier on time, we intervene and again, we look at evidence and research and we pick up, uh, women who are in the high risk of developing breast cancer, and we offer them a test in this In the case of breast cancer, it's called mammogram, and we offer it at a particular stage in their lifestyle. So people 50 and above get a mammogram. Uh, and we are then able to intercept in that disease. Um uh, pathway. And that screening test then can pick up early onset of breast cancer, which can then be treated and be made. Um, you know, the many breast cancer is now kind of considered in many cases, a treatable condition, because if you're identified early, um, then you can be, um, you can be treated for it. So to develop a screening program, we need to be very familiar about the disease. Pathophysiology. So what is the steps before, um, a person clinically manifest with the disease. We need to also understand at what stage in, uh, in that period when a healthy person, um uh develops a clinical condition at what stage? We can provide that screening tool. And that is the period when we then have to intervene. It will be different for different age groups for different conditions. And and that's why then we then can know that that is the time we can, um, a instigate a screening tool, a screening test. But we also know, uh, at what intervals we need to then repeat the screening test. So mammogram is done, and then a mammogram is repeated every so many years again because we know that from the pathophysiology that, uh, if you've got a negative mammogram now, you should be okay, provided no other physical conditions or other conditions change in you for a few years and then you can pick it up again. So, for example, cervical cancer screening program for younger women is every three years every five years and and so and then it it it expands, Um, as you as you go great older. It becomes every five years. We know from the pathophysiology of how a healthy woman then develops cervical cancer at what stage is in their reproductive cycle. We've got to intervene and do the screening test. So this is very important to understand the natural history of the disease before we can put a screening program in next, like please. So in the United Kingdom, all of this evidence and research and review and, um, making sure that the screening programs are in place are done by the National Screening Committee. What do they do? They review the state of the evidence for the recommend recommended disorders. They also cover the chronic diseases that need, um, uh, screening program. So So, for example, they make the decision that for prostate cancer screening, uh, the evidence is still not sufficient for us to introduce a population level screening program. Whereas for di diabetic retinopathy, there is sufficient evidence to, um to develop a screening program. So therefore, you know, chronic disease, uh, chronic diseases can be intercepted by the screening programs. They also look at where evidence is lacking, but review supportive pilots are identified for comedian bowel cancer screening that was made available But now they are established programs for comedian bowel cancer screening. So the evidence is caught up. And now we've got, uh, implemented screening programs for comedian Bowel. So the national screening committee in the UK makes those kind of decisions. Next light, please. And what evidence is required? So how are these expert body's making these decisions? So, um, the NSC modification of the W h O approved criteria and you can look up this, the Wilson and you gonna, um uh is an evidence based approaches to house screening tools. Um uh, screening programs can be established and you can look up their, uh, their kind of, uh they're paper which says that the evidence that we required to make a test a screening tool is based on the condition we're developing The training tool for how predictive the test is will come to come to that in a minute. What are the treatment that's required? So you might put in a test, and then the test means that the person who's identified to have a positive test needs to have quite a significant intervention. Um, which means that the harms from the intervention might outweigh that the screening program tool. Well, that's important for us to know as well. So because, you know, if it means, um, that somebody, uh, is going to be put more to risk by, uh, by some intervention procedure. So, for example, for bowel cancer screening, you know, colonoscopy is used now. Colonoscopy in its own right has got a lot of complications. So now we've used something called, like a fit test. So it's, you know, it's the fit test of screening two or possibly not. So those are the kind of diagnosis and interventions and evidence based that we need to identify before we do before we, uh, intervene and say a screening program is a screening program and then the screening program. How is that going to be, um, rolled out? You know how easy it is or who's going to do it. All of those things have to be taken into account before a screening test or a tool becomes a screening test or a tool next. Likely. Yeah. So that's what I was trying to say. Yeah. Keep clicking. Yeah, that's one. Thank you. No. Next one, uh, validity of the test. Yes. So Oops. The one before. Please. Thank you. The one. Yeah. Thank you. So, in order to assess the suitability of a screening test, it has to be valid. It has to be acceptable. And we have to also think, think about the cost of the test as well. So that's quite important as well. Um, so that's why um the, you know, it's important to check the validity of the test. So next, like this, And how do we check the validity of the test? So we have to do some major calculations, and this is sometimes where our maths comes into being. Okay, so every test we put through through this, um, kind of analysis, So we identify the people who are identified to have a true positive test. Then we identified those who got a true negative test. They also identify people who've got false positive test and people who identify as false negative test. Just bear with me as I go through this because this might take a little bit of time if you click next, please. Okay. So the sensitivity, the validity of the test is based on the sensitivity and the specificity. Okay, So the sensitivity is the probability of the test being positive, given the disease is pre present and the ability of the test to pick up what is testing for. So, for example, for chlamydia screening. So the folks of chlamydia screening the sensitivity of the test is the probability of the chlamydia screening test, which is very much, you know, peeing the pot soup in the pot and then that gets tested. Now, how sensitive is it in picking up people? Healthy people who've got no symptoms with chlamydia? Uh, and the sensitivity of the test as it's calculated by the, um you know, by the chart that we've got before, which is how many true positives okay, are identified through that test over the top over the number of true positives and false negatives. Okay, so the basically the number of people who are positives over all the people who have been screened will give us the sensitivity, okay, And then the specificity is the probability of the test being negative, given the disease is absent the ability of the test to reject what is not being tested for. So if we pick up all of the people who have not tested positive but there could be false positives or false negatives within that. That gives us the identification of specificity. OK of a test. It's a bit of a complicated way of calculating. So my suggestion would be that you look this up in your textbooks and then drop me a line if you feel you don't understand this. So screening tests are more reliant and more valid if their specificity is high. So if they're picking up more, uh, and certain tests will be more specificity is high, then they're more valid. But the sensitivity and the specific city helps us to identify which which screening tests are likely to have a population health benefit. Next slide, please. The next one, please. Okay. And then we come to another, um, bit of complex concept and this is called the predictive value of the test. So the predictive value of the test is is how good is this test? Okay, so you've identified. Is the test sensitive or specific? So is it picking up more people positive, or is it picking up more people who are false, positive and and and that gives you a sense of how good the test is and then you have to identify using those concepts as long. What is the predictive value of the test? And this dissent depends as on the disease prevalence. So if you go to younger population groups where chlamydia is really prevalent and you need to identify the predictive value so you probably likely to find more sensitive and more more sensitive people with positive chlamydia test screening because young, younger people have more risk, um, risk taking behavior. If you apply the same test to an older population, you'll probably find that you're not picking up as many positive pace cases. But you might be picking up people who are probably not positive, but they're being picked up anyway. For some reason, they've just been picked up and said they're false positives. So the positive predictive value is the probability of the disease being present, given a positive test result in a particular cohort of people where the disease is more prevalent. So that's the probability of the disease being present. Okay in that, and it gives that positive test result so that again helps us identify whether we do a chlamydia screening in younger population breast screening in over fifties cervical cancer screening in younger women, and that gives us that positive predictive value. The negative predictive value is gives us the probability of the disease being absent. Given a test is negative. Now, how sure can you be if, if a screening test says it's negative, how sure can you be? And that's that negative predictive value. And this is important because this is what information we need to explain. Test results to people next slide, please. Okay, if you keep screening. Okay, So I think I've I've explained slight 20 which was a slide before about how you're getting two positive and negative predictive value. And then it is important to also understand that a screening test has to be relevant for the condition. It has to be an important health problems. So breast cancer debilitates and kills young women survived. The cancer screening kills young women. Chlamydia screening is very important because chlamydia is a health problem for younger people. If it's not detected early and not treated early, people can be left with fertility or infertility problems in future life. So it has to be a health problem that is a burden of disease in a population and the disease also has to have a natural history. That's well understood. So we need to understand the disease pathway. So there has to be a problem. Um, uh, that, uh, that is a latent to a declared disease. So remember that lead time we need. We need to know the pathophysiology as to how a patient becomes, um, from healthy to, uh, sort of, uh, sort of a clinical manifestation case. So we need to understand that disease pathway. It also needs to have a detectable risk factor or disease marker latent period on early symptomatic stage. So, for example, in cervical cancer screening, we know for sure that there is a lead time between, um cervical changes that happen in a woman and then when they when they develop, uh, manifestation of cervical cancer. But what we know is that there is a lead time, which is quite long, whereby the cervical, um, cells change, and there are several stages of that changes. And if you could diagnose that with the smear test and identify those cervical um, cell changes early, then we can intervene and make sure that the person is treated early and they don't want to develop that cancer, but because we studied cervical, um, cancer. For many, many, many years we've studied, um, the pathophysiology and the changes in the sub cervix. We now know that we can put a very, very robust screening program in for healthy women and that we pick up those changes early and that can, that can make a difference to women's lives. Also, it has to be a cost effective intervention because if the cost is so expensive that to pick up one patient we have to spend significant amount of money, then it probably is not going to be a good enough screening tool or a screening test, because, um, we'll have to do it for thousands of people to pick up one person. And and that might not be viable as well. So the condition is also quite important in deciding where a screening program is going to be viable or not. Next, like please. And then, as I said, the test, the test has to be simple. It has to be safe. It has to be precise. It has to be validated for a particular conditions. So going back to those sensitivity specificity. Positive, positive predictive value, negative predictive value. We need to be very, very sure about the test. And then the distribution of the test valleys in the target population should be known as well. So it's important for us to know that, you know. So if I'm picking up, if I'm looking at cervical cell changes, then I know for the target population. If I if I screen 100 women, I should be able to pick that up for most women rather than only two or three women. So that's what I was trying to say before the test should be acceptable to the population. Now we can't introduce a test and say, Okay, well, we've we've introduced this test. This means you need to go in bare yourself, um, and and somebody has to examine you now that might not be acceptable to certain cultures, to certain populations. Um, so we need to be mindful that we can't pick up a test and run with it. If if there is no evidence that it will not be acceptable, there should be in a great policy on further diagnostic investigations of individuals with positive test results and on the choices available to those individuals as well. So, for example, if you say right, I'm screening you for bowel cancer. And if the investigation comes as positive, then I'll have to put you through some more tests and more more investigations. And you need to have these very significant drastic surgery to yourself. And you might say, Thank you, Doctor. I'm 80 years old. Um, I'll take the risk and I live with it. I only have another couple of tests, uh, years to live. I don't want to go and put myself at risk of a bowel perforation and all sorts of other things. I'd rather not have it. But if you're a 50 year old and you say, Well, you know the test that results in a coloscopy is important and it's, you know, it's it's it's not as risky as it should be. And it can take out, uh, unhealthy cells early that might be acceptable to people. So what happens after a test is quite important in choosing a test for a screening tool. And then, you know, the National Screening Committee battles with all of this evidence day in and day out, and then they are also looking at age criteria. How frequently as well when they're deciding whether whether the test is suitable for a screening tool. Next, like please. Okay. So remember, at the beginning of the of the program, we talked about all of those screening programs, and these are some of the screening tests. So the Guthrie tests is used in neonatal to check for many metabolic conditions. Um, mammogram is a test to check for breast cancer disease. Fecal occult blood is used to screen bulk cancer. Um, digital retinal photography is taken for people who are diabetic, uh, to make sure that they're they're not becoming. Um, you know, the diabetes is not affecting their blood. Uh, sorry. The their their eyes. Um uh, and you know. So here is a test of all of these, uh, list of all the tests that can be done to make sure that the that the tests are are suitable for the screening programs. Next slide, please. Yeah, and we talked about this, that they there has to be an effective treatment. So no point you kind of screening somebody and saying right, you are at high risk or we've we've diagnosed early disease or you're at high risk of disease, but we don't know what to do with it now. So if you're at high risk of disease, the treatment might be or the management plan might be that we screen you more frequently. So for cervical cancer screening if we diagnose women earlier on, um, in the early stages of cancer, uh, of sort of early cell changes than what we do, is we We bring their screening closer and we screen them more frequently so that we can pick up early, uh, changes that are cancerous and can treat it early as well. In breast cancer, disease is the same thing. So if he identifying illusions, we take them out with five to them. If they're benign, we just keep them under observation or if they're malignant, then we put them into treatment Regime. There has to be agreed. Evidence based policies covering the individuals should be offered treatment and appropriate treatment to be offered. It's absolutely vital you cannot start screaming screening program, and it's almost criminal to start a cleaning program if you cannot provide a subsequent management program for it. So my a friend of mine is trying to introduce cervical cancer screening in India. Now, the thing is, um, the technology is not there. The labs is not there. So? So the the debate we're having is Do we screen everybody or do we only screen symptomatic women? Because the the test we know from the Western world works. But, um, we know for sure. If you have to give it to every person in India, the population is very big. The infrastructure is not there. It's costly. Um, can we actually do it or not? And those are the kind of discussion's and dilemmas we have. Um, OK, next slide, please. Okay. Yeah. Next slide, please. And Q. So the screening program has to be, um, it has to come. It has to be tested on a quality, high quality, randomized controlled screening trial. So you have to not just say okay. Well, the screening program, this screening test is good, and and we want to just run it. You can't do that. You have to run randomized control programs where you put a group of people through the screening program, uh, a group of people without the screening program, and then you identify whether the screening program is actually making a difference in healthy people. Um, and evidence that the, um that the complete screening program, the test, the diagnostic procedure, the treatment and the intervention is clinically, socially, ethically acceptable to the health professionals and the public. So, um so So that is another thing that has to be tested and and through those programs of reviewing the evidence and actually running some randomized controlled studies, we can also test those out because we could have cluster studies within them to actually also take the views of the clinicians and the people who are undertaking those tests. And many of them are being run for safety things like the prostates, um, prostate screening programs as well, Because in certain parts of the world process screening programs, um, are taking place. Um uh, but in the United Kingdom, it it's not. And and that's because the evidence is still not clear that for our population, that will be the best way of doing it. And and some of in some some states, it's come into place in some states isn't because the evidence is still being developed next, like please and the opportunity cost of the screening program, Um, should be economically balanced in relation to the expenditure medical care. So, as I kind of said, if it takes a humongous amount of time to do one or two or three tests, um, or if it's a if it's such a costly program, that too, you know, you know, to identify one case, we're having to spend millions of pounds, then the opportunity cost of actually doing the screening program has to be balanced out compared to whether we just find something else instead. And the benefits of the screening program should outweigh the physical or psychological harm. So, you know, um, as I said, you know, down screening program Parents these days are choosing to say, you know, thank you very much, Doctor, that you said my my add born child may may have downs, but people with down survive have productive life. So I'm happy to go ahead with the program. Uh, 222 with with that pregnancy, have another couple might be quite psychologically traumatized by even having the choice of doing that, and they might just say No, thank you very much. We'll take the consequences of whatever and we won't even have the screening, too. So you know, those kind of ethical dilemmas should be also considered as part of the screening program and then should be a manage. And there should be a process of monitoring the quality of the screening program. That's very, very important. You can't set up a screening program and think, Oh, it's running all right. It's speaking of the people it's going along. Our screening programs in the UK have got a significant amount of quality and assurance and and sort of, um uh, sort of, um, kind of peer review happening all the time to make sure that the screening program is picking up the right people. It's not causing so much harm. It's, you know, any complications from it? Is it picking up more false positives? All of that constantly happens on the background screening program, and that's why the screening program continues to have that, uh, bit of quality assurance and standards are are set quite high so that we're not harming people, but we're picking. We're picking up people early and making the benefit come to the population Next slide, please. I'm probably going to be halfway through this, uh, this set of slides, but we'll carry on and see how we get to next. Like please. Thank you. So, yeah. Keep going, please. Thank you. Yeah. So then the feasibility go back. Yeah, the feasibility. So, as I said, identification of the target population, proportion of the target population that to be examined. Um So, for example, like as I said, chlamydia screening is for young people. Breast cancer is for older people. Why are we not doing breast cancer for younger people? So all of that comes from that evidence based on the feasibility as well and facilities for diagnosis and treatment. So mammograms to set up mammogram, um, is quite an expensive task. But if we just say to have a mammogram, you can only come into the hospital. That's not gonna happen. So what happens in our, um, in the UK is we've got vans which take the mammogram machines into the communities where we know women are probably scared, and we want to come up to a hospital and we provide that screening program in there, so facilities should be there to deliver the program. There should be a referral and a call recall system. So if you don't respond to your to your, um uh, invite, then what happens to you and then Cosper cases detected as well. So, you know, as I said, you know the cost to identify one case is also detected and as used as a part of the feasibility of getting a screening program up and running next slide, please. Okay, this is again another interesting concept, and I think it would be good if I spend a little bit of time on this. So the effectiveness of a screening program is based on the length bias and the lead time bias. Okay, so the length bias is that likely to detect individuals with longer preclinical phase than those with more aggressive disease? And individuals with longer preclinical phase are likely to have a better prognosis. So length bias. It's likely to detect individuals with the longer preclinical phase. So So, as I said, before somebody develops a cervical cancer, there is small changes that's happening in their cervical, um, cells. And if we can pick that, if you can pick that stage up, um, then you know there, there there is way that we can impact on it. But sometimes that can impact on the screening program. Um, by giving us assurance that they're not developing a disease because we're not screening them every single year, we're screening them at regular intervals, and it might be that that that phase could get shortened In some women, the lead time bias is the survival time for people with screen detected disease and is no longer simply because they are detected at an earlier point in the natural history of the disease. So your screening for cervical cancer, but you find out that somebody has already got cancer and you intervene. You take out that bit of cancer. You keep screening them. They don't develop cancer anymore. So they are now benefited from that lead time buys because that you know their their their their survival time is now improved because their screen detected a disease that they already had had. Um, yeah, And then there is the There is the concept of the pop, the popularity paradox, which is the over diagnosis. So sometimes screening tools can over diagnose this over diagnosed conditions, and that can be, um, can be harmful for some some people as Well, so that's why it's quite important to understand the effectiveness of a screening program. Before we part, we put we put it into a population which is completely healthy. It might be complex concepts. These. So please bear with me. Go back to these slides, read them up, and if you've got questions, come back to me and I can take it, take you through it again. Next slides, please. Okay, so this again, evidence has showed us that what is the difference between those who attend and those who do not attend the screening program now? Factors who, uh, factors associated to who? Those who attend Normally, if you're educated, you know that the screening program will help you to, um, identify disease early. You're at a high risk at a party for for whatever reason, for, um, for a condition. Um, so they're generally healthier. They, you know, and and those are the people who take up the screening program. And the next list is people who do not take up a breast screening program. So, for example, um and and, uh, and we have to try harder to take the program to them, to make sure and assure them that the program will heal them more benefit rather than harm. Um, uh, and those are some of the lists, um, that we've got. And again, these are evidence from, um, from sort of evidence of running screening programs for many, many years. Next slide, please. Okay, I think we've talked about cost effectiveness, so let's just move down this. Okay, Um, so then percent teachers of versus frequencies. So this gives an example. Lets you skip this one because I think you can read this in your in your in your leisure and just the their answers are there as to how you counsel somebody who's got, um, a predictive value of of sort of a downs, baby. And how do you communicate that? So these are the types of evidence that's used to make sure that we've got the robust evidence behind each screening program. So randomized control trials, time trends, case control studies, modeling because, remember, not for every screening tool are we going to get thousands and thousands of people around randomized control trials. Random control trials are also very, very, um, expensive. So it's important that we understand that it will not always be a randomized control trial. But there'll be other evidence base is that we can look into systematic reviews or another one. So we could take a whole lot of published evidence and do a systematic review, and that can give us evidence whether we we go on to develop a, uh, screening program or not. Next slide, please. Okay, Come to the conclusion. Okay, we've run through that quite quickly. We've got some time for questions. So in conclusion, screening is an important public health prevention concept, and certain criteria need to be chosen. And I think we've gone through that. I know. I've galloped through it. Um, so please take some time to familiarize yourself with it. We're not expecting you to be experts, but, um, when you counsel somebody who's come with a positive or a negative test, you should be able to tell them, um, you know the importance of it. And there are other online e learning tools that you can access This, um, this training from So So, um, do go and look for that, uh, as well. Um, you and and certain criteria need to be chosen to decide the introduction and implementation of the screening program. And I think we've gone through that, Um, the screening program is susceptible to length and lead time bias and over diagnosis because we could over diagnose people. The lead time means we could identify people early or late, and the length time means we could pick up somebody in their space, and we can tell them that they're negative, but they could develop aggressive disease very soon. So all of these impact on what we are counseling are people for after a screening programs, positive or negative result. But the important importance of communication. Um, communicating a screening importance of a screening program, the positive or the negative value with key people is absolutely paramount. Um, because you could lose people. You could get people to be identified early or late or, um, or give them a chance or worry them unnecessarily. Some of them involve Children, some of them impact on their lives. So it's important that communication is really, really key. Next, like please, and I think that is the end. Okay. Do we have any questions, Claudia? Um, not that I've seen in the chap. If anyone wants to run mute themselves. And ask a question. Please feel free. I will be also posting the feedback form and the certificate in the chat so you can download and fill it in as well. But please feel free to, um, you and ask any questions while we have five minutes left. Thank you. Other than that, you can get five minutes back. And I'm sure you've got busy schedules. How is everybody today? I know you put in the chat where you all joined from. Oh, good. Thank you. Okay, good. Okay, so we've got 10 people on here today, and I think they're very keen to go into the next lecture. That's okay. No problem at all. This was a heavy, heavy lecture today, but I'm trying to pick up key things from the public health lectures that you will need as a clinician wherever you practice. So I'm trying to gallop through them. Um, but please feel free to ask me any questions because today's lecture I understand, could be quite heavy. As a concept, I put my email address in the chat. If anybody wants to contact me, okay. Thank you, doctor, for your time. And I will get Um, yeah. As I said, um, anybody wants to contact me. That's great. And I will give them back five minutes. Thank you, Doctor. Take care. All right. There, again. Doctor, please. Going up at this representation? Um, sorry. I thought you said you were gonna give us the presentation. Right. Your presentation, uh, available. It's all recorded. Okay. Okay. Thank you.