All correct, Juan

But, this does not mean that physicians do better. Or, to re-formulate the question, which essentially was the reason for the birth of EBM: how do physicians know?

It seems that have by now learned about the value of research evidence (strengths and limitations of explicit knowledge) and we are going back to full circle (and probably justifiably so): what is the role of experience, that tacit knowledge that physicians acquire during their career?

Best

ben

From: Juan Gérvas [mailto:[log in to unmask]]
Sent: Friday, May 30, 2014 1:44 PM
To: Djulbegovic, Benjamin; [log in to unmask]
Subject: Re: Statins adverse effects, level of evidence

-the critical question is to "believe" in "risk tables" as "decision tables" and use it in personal care without having "impact analysis"
-the general idea of transforming a cardiovascular "risk table" (prediction rules) in a cardiovascular "decision table" (clinical decision) is very risky, as we have no "impact analysis" in most cases; see attached paper (Ann Intern Med, 2006)
-in fact, we have many studies about the validity (specificity and sensibility) of the "prediction" and the results are very poor
-the "prediction" is right (according to risk tables) but in practice, after 10 year you can notice that the "prediction" does not work, does not fit with the patient's medical history.
-this is because the "risk" is not for "your patient in front of you" but about someone of the "patient' population" who "math" with someone in the "refering population" (Framingahm in most cases)
-that is, we are transforming a "population risk" in a clinical one having no enough knowledge to do it.
-the prediction value of the risk calculators is similar to a crystal ball prediction (the only "use" is to increase the apparent scientific base of an a-scientific decision)
-un saludo
NOTE 1. A crystal ball is a crystal or glass ball believed by some people to aid in the performance of clairvoyance
NOTE 2. Ignoring social factors in clinical decision rules: a contribution to health inequalities. The debate surrounding the concept of cardiovascular risk estimates for decision making when treating arterial hypertension may be a good illustration. According to this concept, the decision to treat hypertension would not be based on blood pressure (BP) threshold, but on the patient's estimated absolute cardiovascular risk, assessed by age, sex, BP level, tobacco consumption, cholesterol level, high-density lipoprotein cholesterol, glucose intolerance and left ventricular hypertrophy.3 The variables and equations used in the models are those available in international cardiovascular cohorts or databases and thus ignore the psychosocial context of the patients, although adverse psychosocial conditions were associated with a mean 2.7 increased risk of myocardial infarction and contributed to 35% of the population attributable risk in the recently published InterHeart Study, in line with previous reports
http://eurpub.oxfordjournals.org/content/15/5/441.long

El 30/05/2014 17:29, Djulbegovic, Benjamin escribió:

Jim,

Thanks. See my responses below.

Best

ben

From: Jim Walker [mailto:[log in to unmask]]
Sent: Friday, May 30, 2014 10:10 AM
To: Djulbegovic, Benjamin
Cc: [log in to unmask]
Subject: Re: Statins adverse effects, level of evidence

Hi Ben.

Thanks!

Two questions:

1.     Could you send references to the few best papers you refer to?

BD: the classic is Pauker & Kassirer threshold equations.

1.            Pauker SG, Kassirer J. The threshold approach to clinical decision making. The New England journal of medicine. 1980;302:1109 - 1117.

2.            Pauker SG, Kassirer JP. Therapeutic decision making: a cost benefit analysis. The New England journal of medicine. 1975;293:229 -234.

I think Paul Glasziou, David Sackett, Gordon Guyatt and many others have also written some papers discussing the issue how to weigh benefits vs. harms.

Here are some of our references along the same lines (ref #1, #11,#13, #14 show equations I alluded to in my earlier post-these papers may be available through the open access. Ref#1 formulates the threshold equations in terms of NNT and NNH); note, however, they are written from perspective of expected utility theory. We have recently moved away from EUT along the lines of dual processing and regret theory. People’s preferences under dual processing or regret theory will be different than under EUT, which may result in a different calculus/recommendation. And, that is a crux of the problem in this entire debate (about weighing benefits vs. harms).

1.         Djulbegovic B, Hozo I and Lyman G. Linking Evidence-based Medicine Therapeutic Summary Measures to Clinical Decision Analysis. MedGenMed, January 13, 2000 http://www.medscape.com/Medscape/GeneralMedicne/journal/2000/v02.n01/mgm0113djul/mgm0113.djul-01.html

2.         Djulbegovic B, Hozo I, Beckstead J, Tsalatsanis A, Pauker SG. Dual processing model of medical decision-making. BMC Medical Informatics and Decision Making.2012, 12:94.

3.         Tsalatsanis A, Barnes LE, Hozo I, Djulbegovic B. Extensions to Regret-based Decision Curve Analysis: An application to hospice referral for terminal patients. BMC Medical Informatics and Decision Making 2011, 11:77 (doi:10.1186/1472-6947-11-77)

4.         Tsalatsanis A, Hozo I, Vickers I, Djulbegovic B. A regret theory approach to decision curve analysis: A novel method for eliciting decision makers' preferences and decision-making. BMC Medical Informatics and Decision Making 2010, 10:51

5.         Hozo I, Djulbegovic B. Will insistence on practicing medicine according to expected utility theory lead to an increase in diagnostic testing? Medical Decision Making 2009:29;320-324

6.         Hozo I, Djulbegovic B. When is diagnostic testing inappropriate or irrational? Acceptable regret approach. Med Decis Making 2008;28:540-553

7.         Hozo I, Schell MJ, Djulbegovic B. Decision-making when data and inferences are not conclusive: risk-benefit and acceptable regret approach. Semin Hematol 2008;45:150-159

8.         Djulbegovic B, Hozo I, Lyman GH. Estimating net benefits and harms of screening mammography in women age 40-49. Ann Intern Med 2007;147:882

9.         Djulbegovic B, Lyman G. Screening mammography for women age 40-49: regret or no regret? Lancet 2006;368:2035-2037

10.       Djulbegovic B, Hozo I. When should potentially false research findings be considered acceptable? PLoS Med 2007; 4(2): e26. doi:10.1371/journal. pmed.0040026

11.       Hozo I and Djulbegovic B .Using Internet to Calculate Clinical Action Thresholds. Comp Biomed Res 1999;32:168-185

12.       Djulbegovic B, Hozo I, McMasters K, Scwartz A. Acceptable Regret in Medical Decision Making. Med Hypotheses. 1999;53:253-259

13.       Djulbegovic B, Hozo I, Fields KK, Sullivan D. High-dose chemotherapy in the adjuvant treatment of breast cancer: benefit risk analysis. Cancer Control 1998;5:394-405

14.       Djulbegovic B and Desoky A. Equation and nomogram for calculation of testing and treatment thresholds. Med Decis Making 1996;16:198-199

2. How far is this from capturing your intention?:

"Theoretically, as we and others have shown in a number of papers, treatment can be justified when the predicted the NNT:NNH ratio is equal to the risk of disease outcomes (expressed as a percent). For example, if the risk of cardiovascular disease is 10% over n years, then the benefit (NNT) should be more than 10 times the total cumulative NNH of harms over the same period (that is, NNT:NNH = 10:1). [Although this seems to suggest that a lower NNT:NNH ratio would be acceptable when the risk of bad outcomes was less.]

Of course, the acceptable NNT-to-NNH ratio needs to be decided on by each individual patient in consultation with her physician. For example, a given patient might decide on an NNT:NNH ratio of 2:1.

This is not evidence-based, but can provide a starting point for shared decision making."

BD: NNT/NNH=risk/probability of disease above which we should act =10:1 is the accurate statement from EUT point of view; not necessarily from the point of view of other theories of choice. (More interesting question is how do we elicit the patients’ preferences, so that indeed we are assured that NNT:NNH of 2:1 reflects our patients’ true values & preferences? )

Best regards.

On May 30, 2014, at 8:38 AM, Djulbegovic, Benjamin <[log in to unmask]> wrote:

Theoretically, as we and others have shown it in the number of papers, treatment can be justified when benefit of Rx exceeds its harms by the magnitude appropriate for the disease risk. For example, if the risk of cardiovascular disease is 10% over n years, then benefit should be greater (than total sum of) harms 10 times over the same period. If preferences are taken into account then the ratio needs to be adjusted ( e,g,, if one would prefer avoiding cardiovascular event to statins' harms by 5 times, then benefit of statins needs to exceed its harms by 2 times only and vice verse).

This, of course, should not to be construed as a medical advice or to minimize Juan's important message regarding shared decision -making. However, if some rational guidance is sought, this can be a starting point for discussion.

Ben Djulbegovic

Sent from my iPad

( please excuse typos & brevity)

On May 30, 2014, at 1:56 AM, "Juan Gérvas" <[log in to unmask]> wrote:

-to decide in your situation, Ian, you need a general practitioners who knows you well (you as human being, biology, psychology and social) more than an evidence researcher
-i am not in a campaign against statins but with great concern about its correct use
-there is enough evidence to recommend in general the use of statins for secondary prevention
-there is enough evidence to recommend in general against the use of statins for primary prevention
-please think when we are commenting and working about antibiotic resistence, we are not in a campaing against antibiotics
-un saludo
-juan gérvas

El 30/05/2014 0:12, Johnson, Ian (MAN-CTY) escribió:

Juan - you seem to have taken up a campaign against statins. I, as an evidence researcher, am unsure how to respond. I had an ischaemic thalamic stroke 3 years ago, leaving me with unilateral peripheral neuropathy and central pain syndrome. I am, of course on atorvastatin 20mg. I have muscular 'pain' but only one sided, so I know it is neuropathic and not metabolic. I have no obvious statin-related AEs, other than, possibly, hair loss. My question is, what evidence of benefit:risk is there for secondary prevention, other than theoretical, or anecdotal? Obviously, I would be happier to be without a statin, but as a stroke victim, one always feels vulnerable.

Ian

Sent from my iPhone 5

On 29 May 2014, at 18:57, "Juan Gérvas" <[log in to unmask]> wrote:

Therapeutics Initiative.
Estatinas, efectos adversos. Como era esperable, las estatinas tienen efectos adversos. Revisión.
Statins: proven and associated harms. Be aware, statins have adverse effects. Review.
http://ti.ubc.ca/letter89

Este mensaje no contiene virus ni malware porque la protección de avast! Antivirus está activa.

Este mensaje no contiene virus ni malware porque la protección de avast! Antivirus está activa.

Este mensaje no contiene virus ni malware porque la protección de avast! Antivirus está activa.