Medical science Archives - Page 6 of 8

Blood pressure and the conundrum of medical numerology

Michel AccadJune 25, 2015December 13, 2016Medical scienceLeave a comment

As part of a series on heart disease, Gina Kolata of the New York Times is calling attention to Blood Pressure, The Mystery Number.

And what a mystery it is! Reading Kolata’s piece, one gets a sense that hypertension researchers are chasing after the optimal blood pressure the way Pythagoreans of old sought numeric answers for the riddles of the universe.

Kolata relates:

What about a patient like Glenn Lorenzen, 67, whose systolic pressure was a frightening 220 in October? On a chilly day in December…he had received the good news that drugs and weight loss had lowered his reading to 124. Should he be happy? Should he aim to be below 120? Or should he ease up on the medications a bit and let his pressure drift toward 140 or even 150?

Unfortunately, with Lorenzen’s happiness hanging in the balance, doctors must make decisions “in a fog of uncertainty.”Continue reading “Blood pressure and the conundrum of medical numerology”

On the sagging of medical professionalism

Michel AccadJune 3, 2015September 10, 2021Ethics, Medical practice, Medical scienceLeave a comment

[The following article is published with the kind authorization of its author, Herb Fred, MD, MACP. It first appeared in the Fall 2004 issue of the Texas Medical Board Bulletin.]

For the past two decades, medicine has been a profession in retreat, plagued by bureaucracy, by loss of autonomy, by diminished prestige, and by deep personal dissatisfaction.¹ These ills would be bad enough by themselves. But another malady confronts us—the sagging of our professionalism.Continue reading “On the sagging of medical professionalism”

COI and empirical fundamentalism

Michel AccadMay 22, 2015December 13, 2016Ethics, Medical science, Philosophyconflict of interest4 Comments

Over at the Incidental Economist, Austin Frakt has published a thoughtful commentary on Lisa Rosenbaum’s NEJM series on the obsession over conflict of interest. Frakt is supportive of Rosenbaum’s position but also touches on a dimension to the story which I did not address in my admittedly polemical piece yesterday.

Frakt’s most important statement is actually not in the post itself but in a Tweet linking to it.

I view COI disclosure as (meta) data. Like all data it doesn’t self-interpret. This is the source of all COI-debate: http://t.co/qIyds8T6Bu

— Austin Frakt (@afrakt) May 22, 2015

Frakt is absolutely right and his statement points to a very fundamental assumption that underlies not only the COI concerns, but the legal practice of medicine in general. Namely, the assumption is that in science and medicine, we should “let the data speak for itself.”Continue reading “COI and empirical fundamentalism”

Against the war on obesity

Michel AccadMay 15, 2015September 10, 2021Ethics, Medical practice, Medical scienceobesityLeave a comment

[This essay was published in the May 2015 issue of San Francisco Medicine. The entire issue is devoted to obesity and you may find it on-line here. ]

A war on obesity has been declared. Public health authorities have identified excess body mass as an epidemic threat. With a great sense of urgency, they are mobilizing resources to address this preeminent health concern. To bolster the effort, the American Medical Association has recently decreed obesity as a disease. Local, state, and national political powers are now engaged in its eradication and have enlisted the assistance of a number of celebrities.

But does the war on obesity have clear objectives and a sound strategy? Will the campaign be conducted as a targeted strike with a well-defined exit plan, or will it turn into an open-ended conflict with limited prospects for victory? Will the offensive conform to “just war” principles, or will it be mired in moral confusion? Whatever the answers, I have reasons to object to this war.Continue reading “Against the war on obesity”

Population medicine: The other “dismal science”

Michel AccadMay 5, 2015September 10, 2021Healthcare economics, Medical sciencepopulation medicine4 Comments

[On May 18, the website of the Ludwig von Mises Institute ran a slightly edited version of this article. You can find it here.]

In its current usage, the phrase “dismal science” is a disparagement leveled against mainstream economics for its failure to provide a coherent account of economic activity.

According to Austrian school critics of the neo-Keynesian synthesis, this failure is in large part due to a foolish determination to bring into economics the mathematical precision of the physical sciences. To achieve this precision, neo-classical economists disproportionately focus their inquiry on global measures of economic activity: gross national product, aggregate demand, global supplies of money, goods, or labor, and other variables that lend themselves to quantification and numerical modeling. Lost in mainstream economic analysis is the attention due to the individual economic actor who, by virtue of his or her power of self-determination, is ill-suited for the equation or the graph.

A similar love affair with quantitative methods has rapidly taken over the medical field over the last several decades.Continue reading “Population medicine: The other “dismal science””

What it means to be normal

Michel AccadNovember 29, 2011December 13, 2016Medical scienceLeave a comment

“The artifactual disease” is the phrase George Pickering coined to describe hypertension in the 1950’s and 60’s. In those days, he dominated the debate about the nature of hypertension, arguing against those who thought hypertensive patients who developed complications comprised a distinct entity of subjects. “The higher the pressure, the worse the prognosis,” he would repeatedly affirm. To my knowledge, he did not expound on the J-curve phenomenon, but he surely made a convincing case that defining a disease on the basis of arbitrary cut-off numbers is most foolish indeed.

But since the 1970’s, after clinical trials established the success of anti-hypertensive therapy, and with the growing enthusiasm for “risk-factor modification” and the inexorable rise of population medicine, any attempt to expect rational nomenclature or clarity of thought has seemed increasingly futile.

Instead, we must be impressed by discussions of studies where “Patients were categorized by their mean SBP level over follow-up as very low normal (<120 mm Hg), low normal (120 to <130 mm Hg), high normal (130 to <140 mm Hg), high (140 to <150 mm Hg) and very high (>150 mm Hg). ”

I recently tested myself on a 24-h ambulatory blood pressure monitor. My SBP varied from 90 to 142 mmHg.

No wonder I was feeling out of sorts.

Heterogeneity of treatment effect: additional difficulties

Michel AccadNovember 22, 2011December 13, 2016Medical science2 Comments

An article by Diamond and Kaul in the American Journal of Cardiology outlines additional difficulties for the science of medical predictions.

Some of the problems related to HTE have been outlined by Kravitz et al., as we have previously seen, and Kent et al. offered a proposal to mitigate them. But as we noted, the proposal by Kent et al. assumes a treatment that provides fixed relative risk reduction across the range of risks. This is displayed in Panel A in the AJC paper:

The thin line is the hypothetical baseline risk-outcome relationship, the bold line is the post-treatment risk-outcome relationship. In Panel A, the relative risk reduction is constant. As one moves from lower risk to higher risk, the absolute benefit (vertical difference between the lines) increases.Continue reading “Heterogeneity of treatment effect: additional difficulties”

More on HTE

Michel AccadNovember 18, 2011December 13, 2016Medical science2 Comments

I am very grateful to Dr. James Gaulte for pointing out the paper by Kravitz et al. on the vexing problem of heterogeneity of treatment effects (HTE). The article indeed provides a very clear and comprehensive explanation of the issues, and it is apparent that the proposal by Kent et al. discussed in the last post was aimed at addressing some of the challenges described by Kravitz et al. I agree with Dr. Gaulte that the article should be recommended reading for medical students (and we’re all medical students…), but I will present here additional comments about the specifics of the paper, as well as the general philosophy that the authors seem to espouse. Interested readers are encouraged to review the paper first.Continue reading “More on HTE”

Dealing with variable risk

Michel AccadNovember 11, 2011December 13, 2016Medical scienceLeave a comment

I mentioned in the last post a recent proposal by Kent et al. that would improve clinical trial reporting and—in the authors’ words—lead to “actionable” clinical trial results. The proposal addresses “heterogeneity of treatment effect (HTE)” and the relationship of that effect to the baseline risk of clinical trial enrollees.

HTE is the technical term used to reflect the fact that clinical trials (other than N-of-1 trials) are designed to reach a conclusion about an overall treatment effect, usually reported as relative or absolute risk reduction for the treated population when compared to the control group. Clinical trial results tell nothing specific about an individual subject’s response to treatment.

Clearly, not everyone enrolled in the treatment arm of a given clinical trial benefits from (or is harmed by) the intervention. Attempts to sort out who benefits most or least is usually done by dividing the trial population into subgroups, one characteristic at a time (eg. male vs female, old vs. young, hypertensive vs. normotensive, etc.), and by performing a statistical analysis on each subgroup. Traditional subgroup analyses, however, are fraught with many well known limitations and are not practically useful to help identify those likely to benefit.

In this proposal, Continue reading “Dealing with variable risk”

“EBM” on the decline

Michel AccadNovember 9, 2011December 13, 2016Medical scienceevidence-based medicineLeave a comment

In August 2010, a group of eminent statisticians and clinical trial specialists (Drs. Kent, Rothwell, Ioannidis, Altman, and Hayward) published online a proposal to deal with a major short-coming of clinical trials, the so-called heterogeneity of treatment effect (HTE). The authors offer a refinement in the way clinical trial results are analyzed and reported.

Perhaps sensing mounting dissatisfaction with the blunt tool of ‘evidence-based medicine,’ and perhaps in an attempt to dismiss any further rebuff, Kent et al. introduce their proposal by characterizing the critics of EBM as mere Luddites:Continue reading ““EBM” on the decline”