This thread in intensely engrossed on the research of global warming. I do not
want to distract from that subject.
However I want to take advantage of the title of the topic. Here is a
mini-article, I wrote on a topic that may be of greater personal benefit to
goanet readers, than global warming.
The article after the second or third reading should be self-explanatory.
Readers may want to make their own decision, if the issue ever affects them.
Regards, GL
Omission Bias – in Patient or Physician?
I was interested in Dr. LoConte’s comments about "Omission Bias" relating to
breast cancer prevention using Tamoxifen. (HemOnc Today Jan 25, 2010). She
finds an "omission bias" of the patients / public, and links it to their
“cognitive dissonance” of risk-perception. Yet, the application of the Breast
Cancer Prevention Trial (BCPT) data really shows significant limitations of
scientific success, despite our trumpeting the positive findings.
If one reads the WebMD article on the BCPT study (1), (and other publications);
which intelligent lay-persons or their relatives would do, one will
understandably have serious reservations about taking five years of a
medication for a condition one may never get. From a population-based
perspective, this therapeutic option has its own side-effects; and at the end
of the day, it does not reduce mortality from cancer. For an individual at high
risk for breast cancer based on GAIL model, Tamoxifen addresses a problem
(breast cancer) that may never occur; and if it (cancer) is to occur, the drug
does not prevent the more fatal variety, that is non-estrogen-modulated.
From a cost-analysis perspective, which scientists undertaking evaluation of
the study (and providing NCCN and other guidelines) should assess, the
price-tag is astronomical. Based on US drug-cost, Dr. Melnikow from the
University of California-Davis estimated it to be $1.3 million per
year-of-additional-life for women at the lower end of the high-risk scale. In
Canada, given that country’s drug prices, the cost is one-tenth of that
amount. In third-world countries, the dollar-cost per added-year-of-life will
likely be lower. Yet, in relation to family income, the cost could be
prohibitive. If insurance covers the drug, the cost is enough to ‘break the
bank’, even in rich countries. It is remarkable that respected
oncologists would make recommendations (in articles and at cancer
meetings) without presenting a thoughtful cost-benefit analysis, unless they
are recycling the BCPT data and "standard of care" guidelines in the USA.
It is unfortunate that the scientific community did not embark on a
middle-ground to see if fewer years on the drug would provide a near-similar
benefit with significantly less toxicity (risk of uterine cancer, pulmonary
embolism, DVT, cataracts) as well as cost. The middle-course in medical care
(if possible) is often transcendent; rather than patients refuse the drug or
physicians not prescribe it. The middle-course may be even more important in
the USA, given the healthcare debate in progress. It is likely Dr. LoConte’s
patients who declined chemo-prophylaxis had greater insights than doctors give
them credit for. An astute patient or relative, and most are when the issue
affects them, may even be turned-off by the spurious magnification of benefit
using ‘relative reduction’, instead of providing the ‘absolute reduction’ of
breast cancer occurrence in the BCPT trial.
Like most doctors, I do not encourage (neither do I discourage) patients to get
their medical information from the web. Yet the WebMD article had much more
analytic information on cost-benefit of breast cancer chemo-prevention; than
many medical papers or lectures on this topic. It appears that it is the
physician-presenters who may have an “Omission Bias.”
Reference
1.
http://www.webmd.com/breast-cancer/news/20060724/tamoxifen-prevention-questioned
