Wednesday, September 26, 2007

Who is at risk for venous thrombosis on long haul flights?

A large international study from Leiden attempts to answer some of the questions regarding venous thrombosis in air travelers and is available here in PLOS.This was a large (n=8755) follow-up study (over a five year period) involving employees from a number of companies.

First on all, short flights-less than 4 hours-seem to not be an issue while longer ones may be.

Some interesting observations were made.

Shorter travelers ( less than five five) and taller ones(over six one) seemed at greater risk and- perhaps surprisingly- so did younger folks (less than 30 years of age). So, it seemed best to not be too young, short or tall. Some speculations regarding vein compressions in the short and not enough room for the legs in the tall seemed plausible but why younger travelers. The investigators suggested that one of the many epidemiological traps for the unwary might be in play.This may be an example of the "attrition of the susceptibles". Individuals who are susceptible to a given event are likely to experience it soon after the start of exposure.The younger travelers likely had not been doing long haul flights for very long while the older employees had and those with clotting tendencies may have been deselected-i.e. no longer traveling or perhaps even taking prophylactic measures.

The relationship between risk and "extremes" of height had been made previously as had their other major observation that women on oral contraceptives had an increased thrombosis risk (Incidence rate ratio of 3.6). I had blogged previously about a 2006 JAMA article which presented some evidence that a major factor in the pathogenesis was blood flow alterations as opposed to coagulation system changes brought about by the flight.

The best advice still seems to be to get up and walk around as much as you can on long plane trips. What about the patient who has previously experienced a thrombotic event in temporal proximity to a long air flight and who is ready to travel again? Should they take low molecular weight heparin pre- flight? I think I would.

Wednesday, September 19, 2007

Policy side effects:thinking beyond Stage One

DB 's MEDICAL RANTS recent comments about the need to consider the potential "side effects" of health policy decisions stimulated me to revisit Thomas Sowell's Applied Economics-Thinking beyond Stage One. Economics seems to be much about effects and side effects.

In this book Dr.Sowell examines economic policies in terms of their "later repercussions" not just their immediate effects of their apparent aim or their "hoped-for" result.For Sowell, a program's "unintended consequences" are often foreseeable if the processes involved were considered in terms of the incentives and constraints and not in terms of the desirability of the goals. Rent control brings abut housing shortages,black markets and poor quality housing not the
readily available, affordable housing promised for the poor.The caps on earning found in some Canadian provinces predictably brings about shortages and long waiting lines as described by the former Canadian, The Physician Executive. Tendency to cherry pick patients and treat the chart and emphasize quality measures while ignoring other important features of patient care were clearly foreseeable consequences to P4P.

The seasoned physician knows he may have to wait a while to learn about the problems that may occur with use of a new drug (i.e. those side effects not evident in the randomized trials that are done for drug approval). However,the shortages and other problems that are well recognized with socialized systems such as Canada and Great Britain are things that should not surprise us when they appear if similar systems were put into place in this country.

With relatively uncommon,non-acute side effects we often just have to wait and see if in the long term a new drug will cause harm while with certain policy moves using knowledge of human nature, history of how things have worked in the past and analyzing the relevant incentives and constraints we may well know what to expect.

Sunday, September 16, 2007

Applying group data to individual patients-the problem revisited and perhaps a solution sugested

How does one apply the results of even the very best designed and executed randomized clinical trials (RCT) to the individual patient? I guess the answer is very carefully and not too literally.

I have written about this issue here in discussing the classic,everyone-must-read, article from the 2004 Milbank Quarterly by Kravitz, Duan and Braslow entitled "Evidence-based Medicine;Heterogeneity of treatment effect and the trouble with averages". It can be found here.

The basic fact is that everyone does not react the same to a given medication.The summary statistic of a clinical trial does not reveal that there is a mixture of

"substantial benefit for some, little benefit for many and harm for a few"

In other words you cannot expect the average effect to occur in your patient.

In the Sept 12, 2007 issue of JAMA, David Kent and Rodney Hayward revisit this issue and offer what they believe to be a solution to the problem. ( "Limitations of Applying summary results of clinical trials to individual patients-The need for risk
stratification",JAMA vol 298, no 10, pg 1209.

They propose that the answer is risk-stratified analysis which will greatly increase the power of the detecting the critical differences in treatment effect but ,the authors suggest is rarely used. I am not sure I have ever seen it used in a major clinical trial publication.This risk stratification is supposed to be a definite improvement over the simple sub-group analysis which typically takes one characteristics( e.g. gender or some co-mobidity) at a time,the problems of which are well known including lack of power and increased likelihood of false positive associations.

Had the authors treated us to a few good examples it would have been more convincing;the one graphical illustration of how this method improves things probably will not turn the heads of many readers.But it is good that folks who know more about statistics and analysis than I do are thinking seriously about improving the way we use group data to manage the patients who have a pernicious tendency to be individuals.

New COPD guidelines-the guideline epidemic continues unbated

Here is a link to comments about the new GOLD COPD guidelines and here are the guidelines. Even with references it is only a merciful 26 pages.

The category of Stage 0 was eliminated which makes sense to those among us who wondered abut the logic of defining the first stage of a disease as a condition that poses the increased risk of that disease.

I was glad to see that mention was made of the problem of overestimating the degree of impairment using spirometry in elderly patients, particularly if one uses the percent predicted methods. This method designates a given FEV1 , for example, as 76 or some other number percent of predicted. This method works fairly well, although it never had sound statistical basis, it just happens to work reasonably well but older folks and shorter people tend to get short shrift and appear to be more imparted that they should be. Further there is a normal decrement in lung function which is incompletely "Corrected for" when one use the percent predicted formula.I don't have a solution for that other than be aware that the old folks' pulmonary function impairment may not be a severe as the percent predicted value would indicate.

Some of the old time lung doctor treatments are not recommended including mucolytic agents and continuous antibiotic prophylaxis.

Tuesday, September 11, 2007

P4P and Covert rationing

DrRICH's posting on P4P is a masterpiece and it is only Part One. I have ranted on and on about P4P here wherein I seconded the notion that it was unethical and as such physicians should not be negotiating about the details of the process and here wherein I discussed the disastrous results of an insurance carriers P4P program in Seattle. His posts delve into more sweeping and fundamental aspects.

He tackles the Axiom of Industry that states:

Standardization of any process improves quality and reduces cost.

The axiom may make some sense in processes involving making widgets and it that setting may be able to actually increase quality and decrease cost but for the most part medicine involves processes involving living human beings and their diseases both of which vary widely along multiple dimensions making , for example, treating someone with heart failure as different as it could be from making widgets.

P4P is only part of the current landscape of medical practice which is dominated by managed care. DrRich offers a description of and an insight into this world in which words may not mean what they seem or are usually taken to mean and one in which the goals of the physicians and the managed care companies could not be more in opposition. Simply put, if physicians do their job they may well spend the insurance company's money, while if the insurance company is doing its job it will not spend money.

Practicing physicians who take the time to read his "Manged Care in an age of covert rationing" will never look at what they do in the same way again and if medical educators do not make its reading mandatory they have little defense against the accusation of dereliction of duty.

MEDICARE taketh away and giveth back -sorta

Recently, various Government agencies have been very active in regulating the use of erythropoiesis stimulating agents (ESAs) . The major ESA players are recombinant human erthropoietin (Epogen,Procrit) darbepoetin (Aranesp). In several groups of patients (mainly renal patients and patients with head and neck cancers receiving radiation therapy) clinical studies indicated increased mortality and thrombotic events in patients in whom the targeted hemoglobin was greater than 12. This lead the FDA to issue safety warnings and guidelines regarding the target level of hemoglobin and then CMS to propose limitations on Medicare and Medicaid coverage for the use of ESAs. This is a follow up to an earlier posting regarding this issue bearing some limited "good news".

Unfortunately, not only were renal patients the focus of proposed Medicare coverage restrictions but also were other clinical groups who have received ESAs with clinical benefit. Of particular concern to hematologists were patients with myelodysplastic syndromes (MDS). There is a ten year history of safe use of ESAs in MDS and evidence that there is improved survival and decreased progression of MDS to leukemia as well as decreased transfusion requirements .

Several professional groups ( including the American Society of Hematology, SWOG and ASCO) protested to CMS regarding possible restrictions regarding use of ESAs in MDS patients and apparently CMS listened and made no national coverage determination (NCD in CMS jargon) limiting its use in MDS patients.This gives the green light to its use if there are no limitations imposed by regional Medicare carriers.

So, it is at least a partial victory for the physicians and their patients but battles may still have to be fought with the local Medicare contractors.

Some of us can still remember from the early days of Medicare when the powers that be needed the cooperation of both physicians and hospitals to make the thing work and they promised to not interfere with patient treatment and the physician and hospital fees were not directly determined by the government. The days of " reasonable and customary" charges are long gone and doctors now have to refer to the latest CMS decision memo to see what medications they can use.

Sunday, September 09, 2007

New Asthma guidelines-some more some less

Here is the latest version of asthma guidelines. The full report is 487 pages and is entitled " Guidelines for the diagnosis and management of asthma." Asthma specialists can be appropriately proud because this report is longer than the 304 page tome penned by a joint group (ACC/AHA) dealing with the 2007 guidelines for the management of patients with unstable angina/non-ST segment elevation myocardial infarction. Both overshadow in bulk the rather brief (88 page) guideline publication from GOLD (Global Initiative for Chronic Obstructive Lung Disease) and the 2004 86 page treatise (JNC 7) which still incites seemingly irreconcilable differences between blood pressure experts regarding how to treat blood pressure and can be found here.

Not only are there more guidelines published all the time they seem to get bigger and bigger.The dominate paradigm seems to be "more is better". Recent discussions regarding asthma are suggesting that in regard to mild persistent asthma less may be about as good as more in terms of intensity of therapy even while the guideline verbiage grows and grows.

It will take sometime to contrast the details with earlier versions of the asthma guidelines but one difference I noticed was that there it is permissible ( or mandatory) to not only increase treatment when control is not adequate but it is also allowable to actually decrease treatment intensity when asthma is well controlled.

I will need a little more time to try and wrap my understanding around what I might really need to know after the fluff is filtered out (you can't have a paper that long without some fluff) but here is what the reviewer for Med Page Today had to say about it and here is an overview with some details from Medscape. Long acting beta agonist (LABAs) are not recommended as mono therapy for persistent asthma nor for treatment of acute exacerbations. Lip service is given to long acting theophylline oral medications as an alternative but I suspect the docs using them are hard to find. Fortunately, the panel was not frightened off by the meta-analysis published by the Salpeters,which I ranted about over and over, and continue to recommend the use of the combo treatment of LABA plus inhaled steroids.

The idea that we may not need to treat mild persistent asthma as aggressively (intensely) as we now recommend has been written about recently in two clinical trials in the NEJM and in the form of an editorial in the Annals of Internal Medicine. The NEJM articles can be found here and here.

One of the reason for use of so-controller ( as opposed to rescue therapy) in persistent asthma is the expectation (hope? theory?) that chronic mediation will control or minimize the inflammatory processes so that long term lung function loss will not occur. Short term trials of such therapeutic ploys such as use of rescue combo inhaler of an ICS plus a LABA ( as was done in one such trial ) cannot address the long term concerns and I suspect that ICS will continue to be the mainstay of the treatment of persistent asthma for some time to come.

Wednesday, September 05, 2007

Efficient claims payments is the last thing Medical insurers want

Everyone who has ever been stooged by Insurance carriers regarding medical claims, patients and physicians alike, has to read this entry in the Covert Rationing Blog and , of course, everyone has been stooged. DrRich has this great comment describing how insurance companies screw docs out of their fees.

They accomplish this by employing byzantine rules, by strictly enforcing unintelligible requirements that shift like the sands, by establishing arcane appeals processes, and, when all else fails, by generating a series of black holes into which claims mysteriously disappear, so that (if the doctor still insists on being paid) the claims process must be initiated all over again. Call it the “Shoots and Ladders” model of claims processing.

If we need to squeeze just one more sentence into the medical school curriculum, it should be that one.

DrRick refers the readers to details written by Dr. Stanley Feld in the blog Repairing the HealthCare System.
Go there to learn more alarming and infuriating details.