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Again a second addendum, becauseI think its important:

I have been asked:

"If I am interpreting you correctly, what you are saying is, you think that blood pressures should never be measured unless a person is symptomatic. I’m not saying that is wrong but is that what you are saying?"

The key phrase here is 'unless a person is symptomatic' which begs the questions: what symptoms and who decides.  

I would argue that the systems of screening and risk assessment that cause harm are those that send postal invitations out, or make phone calls, to populations of asymptomatic individuals in the community (that is to people who are not actively complaining or seeking intervention of any kind) ,and especially if, for example, saying things like "and your GP thinks this is a good idea" which is written on invitations for breast cancer screening where I live in Scotland).   

However,  if a person visits a health carer for any symptomatic reason then I would leave whether to take a blood pressure up to that health carer, whilst encouraging that carer to be aware of the dangers of over investigation, and false positives in populations where a disease/risk factor is of low prevalence.  The question of when to check the BP in a face to face 1:1 consultation in surgeries is a matter for individual clinical judgement.  We can all think of scenarios where we would and would not check the BP, but I would avoid checking a BP unless it seems clinically relevant to me.

Owen


On Wed, Oct 31, 2018 at 2:18 PM Owen Dempsey <[log in to unmask]> wrote:
Following a reply I would like to share an addendum:
If I was asked for example: 

"I would imagine you would agree that treating blood pressures of 200/120 likely provides a reasonable overall benefit - if so how does one pick this up without sometimes measuring blood pressure?"

The key phrase here is 'reasonable overall benefit' .. benefit to the individual perhaps, although I would prefer to say a reasonable 'chance' of benefit; but collectively I would say that population based screening of the asymptomatic population in order to detect occasional very high blood pressures causes more harm than good. 

If the population isn't screened then the person with the asymptomatic very high BP would go undetected, and may come to harm because of it.  However this does not, in my view, justify population based screening because: 
 
  1. the minimum level at which BP would benefit from treatment  is not known, this leads to many false positives and much over diagnosis, and morbidity, 
  2. treating the borderline cases leads to expense and side effects, 
  3. there are opportunity costs in terms of what the resources used to screen could be spent on, screening for example takes away time and money to be spent on people who are ill, 
  4. there are financial implications for individuals and for health services, 
  5. and this kind of population based care makes it harder for individual practitioners to provide inter-personal care because people are de-individualised by the process.  

The health services, and individuals, have limited resources, this means that the care that can be provided is not without limits.  I do think it is reasonable for the population at large to made aware of healthy lifestyle advice, such as smoking is bad for everyones health, just as poverty, and lack of access to healthcare is bad for everyone's health. 

Owen

On Wed, Oct 31, 2018 at 11:16 AM Owen Dempsey <[log in to unmask]> wrote:
Dear all, 

I think there are two very important concepts being discussed in this thread:   First, just to say, I support Juan's assertion that prediction and decision rules are intertwined, so offering risk assessment is never innocent of harm, and secondly, I consider the basis on which evidence can possibly guide asymptomatic risk and screening assessment practices:  I suggest that should never rely on the impressions formed solely on the effect on the  intended target. Two issues to comment on: 

1)  cardiovascular risk assessment for asymptomatic populations:

Offering risk assessments to asymptomatic populations (including, for example,screening for heart disease risks or cancer) is never simply a case of enabling informed decisions to be made.  Even offering such a risk assessment creates anxiety and a fear for future health. Providing such a risk assessment enforces a decision: whether or not to take action on the basis of the result. In addition, the process provides a false sense that knowing one's risk will improve life in the long run. 

Offering risk assessments, (and screening tests), to asymptomatic populations actually takes away the freedom of the individual to lead his or her life free of the anxiety induced by the offer, and its associated sequelae. A risk estimate or a screening test result, is what could be called a signifier, that his to say: it signifies the 'patient; and the 'carer', to take the right action, to make the right decision 'for them'. There is choice but it is a 'set up', a constrained choice when the freedom not to know has already been lost. Risk assessment and treatment decision cannot be divorced from one another, and so risk assessment always carries risk of harm. 

This matters because if the anticipatory diagnostic process is likely to cause more harm than do good, either individually or collectively , or both, then it should not be offered, and there should be no population based programme for it. I have argued before, and in my book 'Anticipation and Medicine", that such programmes (in the wealthier nations) will inevitably cause more harm than good and should not be offered

2) Do Statins for primary prevention reduce overall mortality?

If they don't then this is a logically empirical reason why they should not be offered.  And, even if they do, this is insufficient reason, on its own, to warrant a population based practice.  This is because it is always insufficient to ask "Does it work?", meaning "Does it reduce heart disease deaths, or overall mortality?". There are other important questions:

Other questions that should address are, For example: 

  1. Do authoritative institutions take into account, as harms, inevitable harms, unpredictable adverse events,  and overdiagnosis  when warranting guidelines (and how do we know)? 
  2. Do they take into account the opportunity costs of such programmes (for example, the reduced amount of money available to spend on other services?)
  3. Do they take into account the way the market induces carers and the lay public to over estimate the actual benefit of such care?  

This matters because, as with much of such care in the wealthier nations, such products (as cardiovascular risk assessments, cancer screening, and Statins)  cause harms:
  1. direct and visible, as in side effects, 
  2. and invisible: as in over diagnosis, 
  3. and financially to individuals, 
  4. financially to public health services for the poorest especially, and 
  5. unknown ( even unknowable) harm for life to fulfil its health potential 
This is why risk assessment can be harmful, and why we should care whether or not patients take Statins.

Note that this topic is the subject matter of the short book I have had published recently and which I would recommend for students/carers being taught about real EBM.

Best wishes

Owen

On Wed, Oct 31, 2018 at 9:56 AM Juan Gérvas <[log in to unmask]> wrote:
-to finish this debate
1/ using any cardiovascular risk calculator in the consultation room to take decisions is like using a magic crystal ball to take decisions (no scientific base, but could be shared decisions)
2/ of course i never even think that you "cherry pick the meta-analysis", sorry, i never ever think that; i wrote " if your prefer cherry picking by the authors of meta-analysis" what is a critic to the way meta-analysis are done, by cherry picking
and 3/ i’m not pro or con statins, i'am only trying to debate about its rational use
-thanks in any case for your intelligent ideas and sorry for my horrible English
-un saludo juan gérvas @JuanGrvas

El mié., 31 oct. 2018 a las 4:17, McCormack, James (<[log in to unmask]>) escribió:
Thanks Juan for your response.

1) really glad you liked the calculator - and thanks to other people who said they also found it useful

2) risk calculators are all about how to help clinicians and patients make decisions - but agree they are not appropriate to use to decide on a specific threshold for treatment

3) not sure why a risk calculator that is used to give ballpark estimates of CVD needs to undergo a formal impact analysis - a formal impact analysis is used to evaluate if a prediction rule will be beneficial or harmful. When used for education to help make ballpark estimates the only outcome of interest is whether or not the person was properly informed - whether CVD events are impacted is irrelevant - a shared decision is the important endpoint

4) I didn’t cherry pick the meta-analysis - if you look at the actual numbers all MAs on this topic show pretty similar results - one should never just read the conclusion of a meta-analysis because as we have shown, many people who publish MAs don’t know how to interpret confidence intervals https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/1471-2288-13-134

The MA I sent and the one you suggested show pretty much the same thing - which is to be expected as they looked at mainly the same trials - although one (JACC) included a few more trials

See below for the result of each MA - the one I used was the JACC and your's was the AIM MA. The overall CVD and mortality point estimates were almost identical, one showed a larger point estimate for stroke and the opposite for MI - but there is such an overlap with the confidence intervals you can’t really say they are any different. Importantly, every point estimate leans in favour of statins. 

Just for the record I’m not pro or con statins - I really don’t care if people use them or not - just that people are given the opportunity to make decisions based on the best available evidence.

A) Any cardiovascular event

JACC MA - 0.81 (0.75-0.89) – primary outcome endpoint so not any CVD event but similar
Arch Int Med MA - 0.81 (0.74-0.89)

 B) Mortality

JACC MA - 0.90 (0.82-0.99)
Arch Int Med MA - 0.92 (0.76-1.13)

 C) Stroke

JACC MA – 0.74 (0.55-0.99)

Arch Int Med MA - 0.92 (0.76-1.10)

 D) MI

JACC MA - 0.78 (0.67-0.94) - CHD

Arch Int Med MA - 0.69 (0.52-0.91)

Hope all the above makes sense

James



On Oct 30, 2018, at 1:59 PM, Juan Gérvas <[log in to unmask]> wrote:

-excellent tool your risk calculator  cvdcalculator.com
-but it is just a risk calculator, a table of risk not a table of decision
-to my knowledge you have not undergone formal impact analysisso you cannot use in a clinical context
-you cannot transform predicition rules in  decision rules https://www.ncbi.nlm.nih.gov/pubmed/16461965
-about women and statins i prefer cherry picking by myself but if your prefer cherry picking by the authors of meta-analysis:
"Statin therapy is an effective intervention in the secondary prevention of cardiovascular events in both sexes, but there is no benefit on stroke and all-cause mortality in women" .https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/1195535
-un saludo juan gérvas @JuanGrvas

El mar., 30 oct. 2018 a las 20:57, McCormack, James (<[log in to unmask]>) escribió:
Thanks Juan - just a few comments - thanks for the info about the sugar industry - very interesting

A) CVD risk assessment
1) not sure why using CVD risk assessments needs to reduce CVD morbidity or mortality - in my opinion their only purpose should be to inform patients about a ballpark estimate of their CVD risk
2) agree that guidelines use them to inappropriately to establish treatment thresholds 
3) what do you think of the risk calculator we developed cvdcalculator.com - always looking to make it better so would love feedback on how to improve it or if we got something wrong we would be happy to fix it

B) Women and statins
I think cherry picking 2 studies that didn’t show a statistical benefit is not the way one should discuss evidence. The meta-analysis (link below) seems to suggest that when you look at all the evidence there is a benefit in women - or am I missing something - would love to hear why this MA is flawed or what the concern is - you said you had lots of concerns


James


On Oct 30, 2018, at 12:25 PM, Juan Gérvas <[log in to unmask]> wrote:

-sorry for the delate in answering, James, i thought the question was over
-about my two questions
1/ do you agree with "it is uslees the global cardiovascular risk assessment in the primary prevention of cardiovascular disease in adults”? 
There is currently no evidence reported that the prospective use of global cardiovascular risk assessment translates to reductions in CVD morbidity or mortality. THIS A KEY POINT IN PRIMARY PREVENTION AS IT IS USELESS THE USE OF ANY PREDICITION RULE https://bmjopen.bmj.com/content/7/3/e013650?rss=1 
Prediction rules are not decision rules but may clinical guidelines transform predicition rules in  decision rules https://www.ncbi.nlm.nih.gov/pubmed/16461965
2/ do you agree with "sugar lobby paid scientists to blur sugar's role in heart disease”?
"Sugar Industry and Coronary Heart Disease Research. A Historical Analysis of Internal Industry Documents" Together with other recent analyses of sugar industry documents, our findings suggest the industry sponsored a research program in the 1960s and 1970s that successfully cast doubt about the hazards of sucrose while promoting fat as the dietary culprit in CHD. https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2548255
-about your questions only one merit more debate, in my opinion
1) reduce cardiovascular events in secondary prevention? - I think they do Yes, almost no doubt in males. Lot of concern in females
For example: Scandinavian Simvastatin Survival Study (4S). Both CHD and total mortality were significantly reduced in men; however,  there was no significant reduction in CHD mortality and no benefit on  total mortality in women (RR, 1.16; 95% CI, 0.68-1.99)
Cholesterol and Recurrent Events (CARE). CHD mortality was significantly reduced in men but not in women
-un saludo juan gérvas @JuanGrvas


El mar., 23 oct. 2018 a las 22:34, McCormack, James (<[log in to unmask]>) escribió:
Thanks Juan for agreeing to participate and appreciate your responses - see below for my response - capitals not because I am yelling but so you can easily see my response

On Oct 23, 2018, at 12:32 PM, Juan Gérvas <[log in to unmask]> wrote:

-thanks, James, everything is clear
-my answers in bold by your questions
-but two questions for you:
1/ do you agree with "it is uslees the global cardiovascular risk assessment in the primary prevention of cardiovascular disease in adults”?

NOT SURE WHAT YOU MEAN - DO YOU MEAN THAT RISK ASSESSMENTS (FRAMINGHAM ETC) ARE OF NO VALUE OR THAT LOWERING RISK BY STOPPING SMOKING, DECREASING BLOOD PRESSURE, BEING PHYSICALLY ACTIVE OR EATING HEALTHY FOOD IS USELESS

2/ do you agree with "sugar lobby paid scientists to blur sugar's role in heart disease”?

I HAVE NOT SEEN EVIDENCE THAT THEY HAVE BUT I SUPPOSE IT IS POSSIBLE. CAN’T INFER MOTIVE HOWEVER. PERSONALLY I THINK WE ARE DEMONIZING SUGAR IN A SIMILAR WAY IN WHICH WE DEMONIZED FAT 40 YEARS AGO. THE PROBLEM IS THAT TO ANSWER NUTRITION QUESTIONS LIKE LOW FAT VS LOW CARB REQUIRE HUGE TRIALS OVER YEARS AND I DON’T BELIEVE THESE WILL EVER BE DONE. I HOPE I AM WRONG


Statins based on the best available evidence - given that as with all evidence, it is never perfect - 

1) reduce cardiovascular events in secondary prevention? - I think they do Yes, almost no doubt in males. Lot of concern in females

INTERESTING - I THINK EVERY META-ANALYSIS I HAVE SEEN SHOWS THAT THE RELATIVE BENEFIT IS SIMLAR IN MALES AND FEMALES - WHAT IS YOUR TAKE ON THIS OR YOUR CONCERN

2) reduce mortality in secondary prevention? - I think they do Yes, almost no doubt in males. Lot of concern in females
3) reduce overall SAE in secondary prevention? - I think they do Yes, almost no doubt in males. Lot of concern in females
4) reduce CVD events in primary prevention? - I think they do No. And we know it from more than two decades

I THINK EVERY META-ANALYSIS I HAVE SEEN SHOWS THERE IS A RELATIVE BENEFIT WHEN IT COMES TO CVD IN PRIMARY PREVENTION - WHAT SYSTEMATIC REVIEW OR MA DO YOU HAVE SHOWING NO BENEFIT - REMEMBER THE REASON WE THINK IT WORKS IN SECONDARY PREVENTION IS BECAUSE OF SYSTEMATIC REVIEWS AND MA FROM A COMBINATION OF INDUSTRY AND NON-INDUSTRY TRIALS 

5) reduce mortality primary prevention? I think likely - all the point estimates are in favour but meta-analyses differ in whether or not the p-value is <0.05 https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/1471-2288-13-134 - they very likely don’t increase mortality No. And in any case, if yes, very little effect so harms are more important than benefits

AGREE

6) reduce SAE in primary prevention? they seem not to but I also believe that there is much inconsistency in definition/reporting of serious adverse events that while interesting we must remember that this is a secondary analysis and is really only hypotheses generating No.

With regards to tolerability
1) RCTs in general don’t show that the adverse effects are higher in the statin group compared to placebo - however the collection and reporting of adverse effects in all trials is at best weak Don't forget cerivastatin. RCT usually are not powered for adverse effects

DISAGREE - IF YOU THINK THAT ADVERSE EFFECTS (ABOVE PLACEBO) ARE SO PREVALENT, THESE STUDIES EVEN INDIVIDUALLY ARE MORE THAN POWERED TO PICK UP ADVERSE EFFECTS LIKE MUSCLE ACHES ETC - YO ARE CORRECT IN THAT THEY WON’T PICK UP ADVERSE EFFECTS THAT ARE SAY 1/1,000

2) enough people complain of muscle aches while on statins that it likely is a real issue but it is really hard to put a number to the incidence We can measure adverse effects with a proxy: rate of adherence to statin therapy was only 50% at six months, and further declined at one year.

DISAGREE - ADHERENCE IS A TERRIBLE PROXY MEASURE OF ADVERSE EFFECTS - SOME OF THE ADHERENCE MAY BE DUE TO PERCEIVED INTOLERABILITY BUT THE VAST MAJORITY IS THAT PEOPLE DON’T PERCEIVE A BENEFIT, DON’T LIKE TAKING PILLS,  DON’T LIKE THE INCONVENIENCE OR THE COST


-un saludo juan gérvas @JuanGrvas

El mar., 23 oct. 2018 a las 0:14, McCormack, James (<[log in to unmask]>) escribió:
Hi Juan - agree this is an old debate but in debate it is always good to find common ground. Would you agree/or disagree with the following

Statins based on the best available evidence - given that as with all evidence, it is never perfect - 

1) reduce cardiovascular events in secondary prevention? - I think they do
2) reduce mortality in secondary prevention? - I think they do
3) reduce overall SAE in secondary prevention? - I think they do
4) reduce CVD events in primary prevention? - I think they do
5) reduce mortality primary prevention? I think likely - all the point estimates are in favour but meta-analyses differ in whether or not the p-value is <0.05 https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/1471-2288-13-134 - they very likely don’t increase mortality
6) reduce SAE in primary prevention? they seem not to but I also believe that there is much inconsistency in definition/reporting of serious adverse events that while interesting we must remember that this is a secondary analysis and is really only hypotheses generating

With regards to tolerability
1) RCTs in general don’t show that the adverse effects are higher in the statin group compared to placebo - however the collection and reporting of adverse effects in all trials is at best weak
2) enough people complain of muscle aches while on statins that it likely is a real issue but it is really hard to put a number to the incidence

Hope the above is clear enough. Just wondering what you think specifically about these points.

James


On Oct 22, 2018, at 2:53 PM, Juan Gérvas <[log in to unmask]> wrote:

-this is an old debate
-the key is the frequency and severity of the adverse effects
Statins for primary prevention and serious adverse events
http://www.cmaj.ca/content/184/7/791.1

-but of course, it is easy to find studies pushing for the classical position:

Statins for the primary prevention of cardiovascular disease
https://www.bmj.com/content/348/bmj.g280

Statins  for Prevention of Cardiovascular Disease in AdultsEvidence Report and  Systematic Review for the US Preventive Services Task Force

-i have sent three links, this morning, and the third one is a critc of the previous ones
Behind the headlines. "Controversial report claims there's no link between 'bad cholesterol'  and heart disease," "Bad  cholesterol 'helps you live longer',"
Crítica a "el colesterol malo ayuda a vivir más. Lo que hay detrás de un titular.
https://www.nhs.uk/news/heart-and-lungs/study-says-theres-no-link-between-cholesterol-and-heart-disease/
-un saludo juan gérvas @JuanGrvas

El lun., 22 oct. 2018 a las 19:24, Kev Hopayian (<[log in to unmask]>) escribió:
What I take away from this is that in the elderly, cholesterol levels have poorer predictive value for primary events and less or no benefit in primary prevention. Hardly surprising, because as you get older, age becomes a stronger predictor. 


On 22 Oct 2018, at 15:41, Juan Gérvas <[log in to unmask]> wrote:

Cholesterol LDL-C does not cause and it is not associated with cardiovascular disease. Do not use statins.
El colesterol (ni "el malo", LDL) ni causa ni está asociado a enfermedad coronaria. No emplee estatinas.
[if you have problems, ask me directly the PDF, for personal use]

Lack  of an association or an inverse association between  low-density-lipoprotein cholesterol and mortality in the elderly: a  systematic review.
En mayores de 60 años, menor mortalidad con colesterol "malo" (LDL) más alto.
https://bmjopen.bmj.com/content/6/6/e010401.full

Behind the headlines. "Controversial report claims there's no link between 'bad cholesterol'  and heart disease," "Bad  cholesterol 'helps you live longer',"
Crítica a "el colesterol malo ayuda a vivir más. Lo que hay detrás de un titular.
https://www.nhs.uk/news/heart-and-lungs/study-says-theres-no-link-between-cholesterol-and-heart-disease/
-un saludo juan gérvas @JuanGrvas

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