Adam, thank you for elucidating the importance of these basic epidemiological concepts in an easy to understand concepts. I just wish that your writing is picked up by the common media, even Fox News!
This was a good read. The appropriate communication of scientific results is hard. The execution of good science is hard. The proper interpretation and analysis of data is hard. I just wrote about how regression adjustments don’t completely control for confounding though they’re often treated that way. Data never speaks for itself.
Adam, thank you. Of course you are correct here. However, the opposite problem also occurs and it can cause huge problems. That is, researchers sometimes treat all manner of variables as confounders when they are in fact not valid confounders. Such faulty adjustment can cause a real effect to disappear from the results.
All scientists should know that a confounder is not just any variable that reduces the estimated association ("effect size") when it's included in a regression. A valid confounder needs to cause the outcome — formally, at least be independently associated with the outcome — and it must not be caused by the exposure.
Here is a real example. I am omitting key details. A research team observed an increasing rate of diagnoses of a medical condition. They suspected that the increase might be an artifact of a policy change rather than a true increase. So they adjusted for the policy change, comparing the diagnosis rates before and after the policy change. That made the increased diagnosis rate largely disappear. From that they concluded that the increased rate did not reflect reality. (They did not publish the unadjusted data, but they should have.) They did not cite any evidence that the policy changed caused an increasing rate of diagnosis. From then on, that team and their collaborators variously claimed or simply assumed that the observed increased rate of diagnosis was not real. That steered the course of investigation into the condition in the wrong direction.
The analysis that used faulty adjustment simply adjusted for a date (year). Any event that year would have produced exactly the same result. For example, adjustment for the year some of political election would lead to the false conclusion that there was no actual trend in the medical condition.
In sum, studies should show raw, unadjusted results as well as adjusted results, and they should justify the validity of each included confounder.
Medical research is riddled with bias, intentional or otherwise. I wrote some research papers in my medical specialty and peer reviewed papers for journals. The longer I did these things, the more sceptical I became. You had to really look hard under the bonnet to find hidden sources of bias, especially so in drug trials, and practices like multiple statistical testing would be hidden anyway. Vaccinations, especially covid vaccinations during pregnancy, are a contentious issue with entrenched opinions on both sides. I personally support the replacement all 17of the ACIP members. Why does Denmark have 7 recommended childhood vaccinations while the US has 14? Why does a US newborn need vaccination against Hep B? That is all you need to suspect financial interests are paramount.
No it’s not “financial interests” Ian - and if you don’t understand the reasoning behind the use of Hep B vaccine at birth, your own bias, due to lack of knowledge on the subject of Hep B infection and the long term risks it carries, is clearly on display!
You imply that it’s somehow financially rewarding for vaccine producers to have babies immunised at birth, when in reality it is the in the child’s interests AND the community’s that this child is not at risk of Hep B in the future, provided the course is completed during early life! Claims that vaccine manufacturers make huge profits from childhood vaccines is an old stale chestnut with no foundation. Please educate yourself about the risks of undiagnosed Hep B and its complications, because anyone who is unvaccinated and comes in contact with the virus, either through inadvertently sharing cups, shavers, or even a toothbrush, or as a child playing in contaminated groundwater, faces a very uncertain future - all of which can be overcome by that vaccine you decry. Even plumbers should be fully vaccinated to limit their risk of inadvertent illness while working!
I was a hospital anaesthetist for all of my working life, so I am more aware and knowledgeable about Hep B than you will be, as a family physician, since this is an ever present risk for us. I suggest maybe you strike a more cautious approach before preaching from on high, in case you are preaching to someone likely to know more than you. Hep B transmission needs exchange of bodily fluids. "Sharing of cups" ! that is just ridiculous and babies are not likely to be sharing razors. Plumbers will contact sewage etc, not a suitable indication for babies
All of those are potential life experience that put people at risk of contracting Hep B, including sharing a cup/drink with someone who unknowingly is infected and has a cracked lip, a dental issue - anything that allows virus into saliva from their blood. You ARE correct, shaving and working as a plumber aren’t direct factors for a baby - whereas vertical transmission from an infected mother is THE greatest risk - but during a lifetime, unknowing contact IS a risk, preventable by post-natal and childhood vaccination. Given the HUGE inequities in the American healthcare system, coupled with the awful maternal and perinatal morbidity and mortality data, please tell us all why, as an anaesthetist, you feel so highly qualified to speak on neonatal vaccination? As a family physician, I’ve delivered hundreds of babies and cared for their mothers, fathers, siblings and grandparents, given thousands of vaccinations at all ages, and never had a single case of a serious adverse reaction, so while you may have experienced the risks inherent in the American system, including the risks of all the blood-borne diseases, I’ve worked hard at helping to prevent even more cases from developing, while also trying to ensure I too didn’t run foul of those same risks.
Do you know a better safer and more certain way to prevent the acquisition of Hep B infection?
I've never understood the concept of the data speaking for themselves. Trump speaks for himself and it's complete gobbledegook.
Ha ha! Very good analogy 😁
Adam, thank you for elucidating the importance of these basic epidemiological concepts in an easy to understand concepts. I just wish that your writing is picked up by the common media, even Fox News!
This was a good read. The appropriate communication of scientific results is hard. The execution of good science is hard. The proper interpretation and analysis of data is hard. I just wrote about how regression adjustments don’t completely control for confounding though they’re often treated that way. Data never speaks for itself.
Adam, thank you. Of course you are correct here. However, the opposite problem also occurs and it can cause huge problems. That is, researchers sometimes treat all manner of variables as confounders when they are in fact not valid confounders. Such faulty adjustment can cause a real effect to disappear from the results.
All scientists should know that a confounder is not just any variable that reduces the estimated association ("effect size") when it's included in a regression. A valid confounder needs to cause the outcome — formally, at least be independently associated with the outcome — and it must not be caused by the exposure.
Here is a real example. I am omitting key details. A research team observed an increasing rate of diagnoses of a medical condition. They suspected that the increase might be an artifact of a policy change rather than a true increase. So they adjusted for the policy change, comparing the diagnosis rates before and after the policy change. That made the increased diagnosis rate largely disappear. From that they concluded that the increased rate did not reflect reality. (They did not publish the unadjusted data, but they should have.) They did not cite any evidence that the policy changed caused an increasing rate of diagnosis. From then on, that team and their collaborators variously claimed or simply assumed that the observed increased rate of diagnosis was not real. That steered the course of investigation into the condition in the wrong direction.
The analysis that used faulty adjustment simply adjusted for a date (year). Any event that year would have produced exactly the same result. For example, adjustment for the year some of political election would lead to the false conclusion that there was no actual trend in the medical condition.
In sum, studies should show raw, unadjusted results as well as adjusted results, and they should justify the validity of each included confounder.
Medical research is riddled with bias, intentional or otherwise. I wrote some research papers in my medical specialty and peer reviewed papers for journals. The longer I did these things, the more sceptical I became. You had to really look hard under the bonnet to find hidden sources of bias, especially so in drug trials, and practices like multiple statistical testing would be hidden anyway. Vaccinations, especially covid vaccinations during pregnancy, are a contentious issue with entrenched opinions on both sides. I personally support the replacement all 17of the ACIP members. Why does Denmark have 7 recommended childhood vaccinations while the US has 14? Why does a US newborn need vaccination against Hep B? That is all you need to suspect financial interests are paramount.
No it’s not “financial interests” Ian - and if you don’t understand the reasoning behind the use of Hep B vaccine at birth, your own bias, due to lack of knowledge on the subject of Hep B infection and the long term risks it carries, is clearly on display!
You imply that it’s somehow financially rewarding for vaccine producers to have babies immunised at birth, when in reality it is the in the child’s interests AND the community’s that this child is not at risk of Hep B in the future, provided the course is completed during early life! Claims that vaccine manufacturers make huge profits from childhood vaccines is an old stale chestnut with no foundation. Please educate yourself about the risks of undiagnosed Hep B and its complications, because anyone who is unvaccinated and comes in contact with the virus, either through inadvertently sharing cups, shavers, or even a toothbrush, or as a child playing in contaminated groundwater, faces a very uncertain future - all of which can be overcome by that vaccine you decry. Even plumbers should be fully vaccinated to limit their risk of inadvertent illness while working!
I was a hospital anaesthetist for all of my working life, so I am more aware and knowledgeable about Hep B than you will be, as a family physician, since this is an ever present risk for us. I suggest maybe you strike a more cautious approach before preaching from on high, in case you are preaching to someone likely to know more than you. Hep B transmission needs exchange of bodily fluids. "Sharing of cups" ! that is just ridiculous and babies are not likely to be sharing razors. Plumbers will contact sewage etc, not a suitable indication for babies
All of those are potential life experience that put people at risk of contracting Hep B, including sharing a cup/drink with someone who unknowingly is infected and has a cracked lip, a dental issue - anything that allows virus into saliva from their blood. You ARE correct, shaving and working as a plumber aren’t direct factors for a baby - whereas vertical transmission from an infected mother is THE greatest risk - but during a lifetime, unknowing contact IS a risk, preventable by post-natal and childhood vaccination. Given the HUGE inequities in the American healthcare system, coupled with the awful maternal and perinatal morbidity and mortality data, please tell us all why, as an anaesthetist, you feel so highly qualified to speak on neonatal vaccination? As a family physician, I’ve delivered hundreds of babies and cared for their mothers, fathers, siblings and grandparents, given thousands of vaccinations at all ages, and never had a single case of a serious adverse reaction, so while you may have experienced the risks inherent in the American system, including the risks of all the blood-borne diseases, I’ve worked hard at helping to prevent even more cases from developing, while also trying to ensure I too didn’t run foul of those same risks.
Do you know a better safer and more certain way to prevent the acquisition of Hep B infection?