.
What to believe?
What makes information credible?
Whom to believe?
What types of data are most or least credible?
The text within
is dedicated to helping patients and caregivers better evaluate
medical claims - to help distinguish between strong and weak
information; how to avoid confusing cause and effect, and how to
better recognize hype, fraud, and wishful thinking.
We can do this
by learning to ask questions of the information we receive, and
by recognizing the factors that can distort medical claims and
scientific findings. These factors include
conflict of interest, and
bias - including biases
common in patients - and by learning about the scientific
methods used to evaluate therapies for cancer and other medical
conditions.
Biases:
different reasons for different groups:
Bias: according to the
Webster dictionary is "an inclination of temperament
or outlook; especially: a personal and sometimes unreasoned
judgment." Bias can influence how one looks at outcomes, and
how tests are constructed in order to favor the result that
is wanted or wished for.
Conflict of interest occurs
when an individual's personal, professional, or
financial interests intentionally or unintentionally
influence decisions on scientific methods, or how data
is interpreted.
Financial
conflict of interest leads to bias: "A financial
conflict of interest, I believe, is any financial
association that would cause an investigator to prefer
one outcome of his research to another. Let me give you
an example. If an investigator is comparing drug A with
drug B and owns a large amount of stock in the company
that makes drug A, he will prefer to find that drug A is
better than drug B. That is a conflict of interest."
~ Marcia Angell, M. D. -
dhhs.gov
Anyone
that develops new drugs or sells supplements has an
inherent financial
conflict of interest in respect to evaluating the
true value of their product or service. As just one
example, this financial bias can lead to
selective reporting
or so-called hype
in order to maximize shareholder confidence and the
value of the company as just one example.
Similarly, scientists who have a financial interest must
disclose these
relationships, and they are inherently less able to
overcome the biases these secondary interests can
create. Consider that by investing in a company a
scientist demonstrates a belief in the value of its
product, perhaps in advance of definitive evidence.
Scientists have an ethical responsibility to avoid
arriving at conclusions ahead of time. The
discipline of good science requires that theories are
tested in well-controlled studies, and that the outcomes
are evaluated objectively before conclusions are made.
Intellectual
bias: Investigators and scientists can develop
unintended biases about the value of their work, idea,
or intellectual property. Investigators may
unconsciously see benefit when none exists, or they may
set up a study in ways more likely to reveal weaknesses,
exaggerate the benefits, overlook unanticipated side
effects, and so on. And sometimes patients will
recommend to other patients what they themselves have
done as a way of validating it. While this may seem
reasonable, a few cases are not predictive of what will
happen to you or to the average patient. See weaknesses
of anecdotes and
observational studies
below.
Denial:
In order to cope with living with a life-threatening
disease, patients or caregivers may develop a tendency to
minimizes the dangers of the the disease, or to inflate the
potential of alternative and other less toxic approaches to
control it. Potentially, denial can lead to missed
opportunities and delays that can make the disease more
difficult to treat.
Fears: Fears
are understandable and human, and sometimes can be
justified. In patients the fear of the toxicity associated
with many standard cancer therapies can form a bias in favor
of claims made for safer alternative, or even
investigational low toxic therapies. Similarly, the fear of
questioning authority may prevent patients from seeking a
second opinion or from exploring appropriate investigational
therapies.
The above
speaks to the need for a strong
independent and impartial agency to evaluate study
findings so that the public can have confidence in the
medical products we ultimately receive and rely on.
Confusing Cause
& Effect
It's natural to
look for connections between one event and another. But it's
important to consider that chance or numerous other factors
could also explain the "effect." Therefore it can be misleading
to form beliefs on observations and anecdotes, even when
supported by logical ideas.
The
significance of so-arrived-at beliefs can range from harmless to
dangerous. A harmless but extreme example is when a
baseball player hits a home run and observes he had eggs for
breakfast that day; who then continues to have eggs on game
days.
But making
observations and exploring potential connections between events
(forming hypothesis) is the starting point of science --
inspiring further research and well-controlled experiments that
prove or disprove the observed possible connections.
Here are some
common and potentially misleading assumptions about cause and
effect related to indolent lymphoma:
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My disease is stable,
therefore the life style changes I have made are helping.*
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An assay predicted my response
to treatment, therefore the assay is proven to be valid.
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My lymph nodes are regressing,
therefore the investigational vaccine I took is effective.
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My lymph nodes started growing
while I took xyz, therefore xyz causes progression.
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My lymph nodes started
regressing while taking xyz, therefore it's effective
against the disease.
*NOTE: Patients with indolent lymphomas may be particularly
susceptible to confusing cause and effect, because the
natural cause of the disease is more variable than for most
other cancers. Therefore, if a practitioner prescribes a
life style or alternative protocol that 100 patients follow,
as many as 30% are likely to do well for a time - not
necessarily as a result of the protocol, but because they
would have done well anyway. This "effect," that has good
probability of being unrelated to the practice, will often
result in strong belief and promotions, as in: "How can you
argue with success?"
This is not
to say some unproven practices are not helpful in some way
or degree. And if the practices are harmless and based
on plausible theory we should not condemn them out of hand,
so long as the patients are informed of the alternative
explanations. In other words, we believe that practitioners
have an obligation to state that their ideas and practices
have not been proven in controlled studies to provide
benefit. Furthermore, patients should learn to look
for potential financial or intellectual biases - such as
does the doctor profit from me using his or her protocol -
and take this fully into account.
Baseball and
the FDA:
Pitchers
want to believe every close pitch is a strike and that the
strike zone is too small. So just as we recognize the
need for a neutral party to call balls and strikes in the
game of baseball, we should also recognize the need for an
impartial agency, such as the FDA, to evaluate claims of
clinical benefit.
In order to test claims for a given drug, the drug sponsor
must conduct well-designed studies that minimize bias and
demonstrate clinical benefit. Without such a system we
would have a "Wild West" environment with no means of making
informed or safe medical decisions, and no good foundation
on which advances in clinical science could be made.
Is the FDA without bias and conflict
of interest? No agency or human being is
completely free of bias, but the agency is committed and
mandated by law to achieve impartiality. There are strong
policies on ethics and conflicts of interest in place, and
criminal penalties can be invoked for violations of these
regulations.
About FDA's Ethics Program:
"The Agency’s ethics program is administered to help ensure
that decisions made by Agency employees are not, nor appear
to be, tainted by any question of conflict of interest. The
"ethics" laws and regulations were established to promote
and strengthen the public’s confidence in the integrity of
the Federal Government. The Agency’s Ethics and Integrity
Branch provides advice and assistance to FDA employees on a
variety of ethics related matters including, but not limited
to, financial disclosure, prohibited financial interests,
outside activities, co-sponsorship agreements, and post
employment."
See
FDA.gov/opacom/ethics/
Is anyone's
perspective inherently more believable?
Perhaps we
can learn quickly from the perspectives of doctors and
scientists who have cancer, as the threatening nature of the
disease is likely to remove any financial biases they may
have had in respect to the integrity of the drug evaluation
system in America. And if a secret alternative cures exists,
won't these professionals have the background and the strong
motivation to recognize and validate these approaches?
Here as an
example we offer the perspective of an inspiring individual
and cancer survivor,
Medical Doctor
"Patients who don’t understand
the difference between information based on theory,
anecdote, historical analysis, or double-blind placebo
controlled studies are making ill-informed decisions,
believing alternative therapies are safer or more effective
when they are not. Even patients who presume that
alternative therapies are ineffective may use them. Why?
When faced with a life-threatening disease requiring highly
toxic treatments with no guarantees, or when dying because
there are no effective conventional treatments, it takes
guts to reject something or someone claiming to be able to
save you, just in case you might be wrong." -
Wendy S. Harpham, MD (NHL survivor) Full text:
amcancersoc.org
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Terminology to
help you assess clinical data and medical claims:
Abstracts |
Theory |
Treatment Response |
Statistical Significance (p-value & confidence)
-
Abstracts:
Abstracts are summaries of larger papers and therefore do
not contain all the available details of the study methods
and data. Abstract conclusions may not be accepted by
experts in the field. Reputable peer-reviewed journals
sometimes require modifications to conclusions from the
original abstract for this reason -- or they may reject the
paper from publication because it was determined that the
methods (methodology) or data did not support
the conclusions made in the abstract. Therefore, it's
important to avoid forming conclusions on the basis of
abstracts. They should be considered only a starting
point for discussions with your doctors and perhaps a basis
for additional inquires and research.
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It's important to note that one must be very
cautious in drawing conclusions from merely
reading an abstract. It's important to read
the full article, understand the
methodology, and the strength of the
statistics and research design to determine
if the conclusions the authors present in
the abstract are reasonable. The better the
journal -- and the higher the quality of the
peer review necessary to be published in the
journal, the more likely the methods and
design, etc. will be good. Even with that,
I've seen some questionable studies get into
good journals. |
Questions to ask:
1) Was the paper published in a respected journal?
2) What types of studies and methods were used to reach the
conclusions?
3) Do papers published by other groups support the
conclusions?
Reproducibility is valued in science, especially when
a finding comes from a different investigative group. The
reason for this is that it reduces the chance that bias, or
choice of methods, influenced the findings or the
conclusions.
-
Theory is
an idea or hypotheses. In clinical science theory is often
based on what is known about the disease, and also perhaps
related factors, such as the immune system. There have been
many theories of disease intervention that have sounded
rational, but haven't worked when tested.
Theories are starting points for experiments and studies.
They should not be regarded as a proof. When someone
tells you that this is how a treatment works and that it is
therefore desirable, you might ask:
What clinical data supports the theory?
Who published the findings, and in what journal?
What are the possible biases?
-
Treatment response:
an often misused term to describe clinical benefit from a
treatment based on a clinical change, such as the reduction
in size of a lymph node.
Treatment responses, however, may or may not result in
clinical benefit - improved survival or the reduction of
symptoms. For example, with lymphatic cancers the lymph
nodes can increase and decrease in size because of transient
inflammatory reactions, which could lead to false
assumptions about the benefit of a treatment or a life style
intervention.
Some questions to ask about response:
1) How long was the response?
2) At what intervals were the responses measured and with
what tests?
3) Did the measured response correspond to clinical
benefits?
4) Who reported the responses and were the outcomes verified
by independent reviewers?
5) How large was the patient sample, and how were they
selected?
6) What is the expected clinical course of the disease?
-
About statistical
significance: In order to
draw better conclusions about data we need to know just a
little about measures of statistical significance.
Statistical
conclusions, about responses to treatment in a small group
of patients for example, are not absolute. Everything
is possible, but some things are very possible, some are
less possible and others are very unlikely -- but still
possible to occur. We draw conclusions with a certain amount
of confidence, conventionally 95% or 99%, but there is still
some chance of an error (5% or lower).
Source:
stanford.edu
So lets keep is simple. We're looking for two measures
of statistical significance in scientific reports:
p-value and confidence
interval. If the p-value is .05 or less, the findings
are statistically significant. The confidence interval (CI)
shows a range that a finding (such as response rate) falls
within.
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Measures
of statistical significance
|
Value or
range that indicates statistical
significance
|
p-value
threshold probability
value that tells you if outcome is due to chance
|
.05 or less
.01 is very good
.05 is on threshold (borderline)
.08 is not statistically significant |
95% confidence interval
(were the study repeated
multiple times, it would contain the true effect 95% of
the time) A range of plausible results. |
71% (95% CI: 42-92%)
83% (95% CI: 63-95%)
94% (95% CI: 63-97%)
In the last example, we might say that we are 95%
confident that the response rate is between 63 and 97%.
The wider the confidence interval the less precise the
reported value or point estimate. |
|
P-value or
Probability value: A
value that results from a calculation that tells
you how likely or unlikely the finding (of a
difference in treatment response as an example)
was due to chance.
Common language for low
p-value: Statistically significant -
means unlikely due to chance.
Caveats about
importance of P-value:
-
Threshold
(cap) is arbitrary, therefore, the closer
the p-value is to the threshold (.05), the
less statistically significant.
-
Statistical
significance does not necessarily = clinical
importance.
-
Chance is
rarely the most pressing issue. Biggest
threat is systemic error (bias) Therefore
more qualitative questions include: Are
these the right pts? Are these the right
outcomes? Are there measurement biases? Are
observed associations confounded by other
factors?
-
P values
provide no information on the results'
precision-that is, the degree to which they
would vary if measured multiple times.
Consequently, journals are increasingly
emphasizing a second approach: reporting a
range of plausible results, better known as
the 95% confidence interval (CI). See below.
Factors that influence
P-values:
-
Magnitude of
the main effect: a larger difference will
have a lower p-value·
-
Number of
observations: a difference noted in a study
of 500 patients will have a lower p-value
than the same differences observed in a 25
pt group.
-
Spread of the
data (standard deviation): if the observed
differences in response are unified and less
spread out, the p-value will be lower (more
statistically significant)
Source: Adapted from American College of
Physicians-American Society of Internal
Medicine
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Formal definition
of a 95% Confidence Interval (CI):
"The interval computed from the sample data
which, were the study repeated multiple times,
would contain the true effect 95% of the time."
Common
language for Cl:
An estimate of
important parameters - how precise or "stable"
is your estimate.
- CI is
often reported with a coverage probability
of 95%
- Confidence
intervals are more informative than the
simple results of hypothesis tests since
they provide a range of plausible values for
the unknown parameter.
The wider the
confidence interval the less precise the
reported value or point estimate.
Simplified example:
Response rate
are:
- New Drug
-- 40/50 pts respond (80% respond)
- Standard
Drug - 20/40 pts respond (50% respond)
- The
difference in response rate is 80-50, or 30%
- This
resulting 95% CI of 30% calculates to:
11%-49%
Since both values
in range are above zero, the treatments are
significantly different. We might then say that
we are 95% confident that the difference in
response rate between the new and the standard
drug is between 11 and 49%.
How do you
calculate the CI?
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Also see:
Return to top
Types of
Clinical Data (most reliable first)
-
Randomized controlled
clinical trials: (Provides strongest
evidence of clinical benefit)
Participants are assigned randomly (by chance) to separate
groups (arms) for the comparison of different treatments --
usually a standard and an investigational treatment. Patient
informed consent is required. Neither the investigators nor
the patient choose the group in which participants will be
placed.
Using chance to assign people to treatment arms helps to
avoid selection bias -- putting
pts in better health in the investigational arm, for
example. It also helps to ensure that the groups will be
similar and that the treatments they receive can be compared
objectively.
At the time of a trial, genuine uncertainty must exist about
which of the treatments is best. These trials can be
"double-blinded" or "non-blinded." In double-blind studies,
neither the investigator nor the participants are informed
of which arm the participants have been assigned to. This
also reduces bias and improves confidence in the
findings.
-
Nonrandomized controlled clinical trials (experimental
studies):
Participants are assigned to a treatment group based on
criteria determined by the investigators, such as prognostic
indicators, and disease type. This study design makes it
possible for investigator bias to influence the findings,
and therefore there is less confidence that the group
receiving the treatment under study and the control group
are comparable.
-
Case series (observational studies):
Studies that describe results, such as responses, time to
progression, etc.) from patients who received the treatment
under investigation. Case series (observational studies)
provide weaker evidence than do experimental studies because
of the potential for biases such as, but not limited to, who
is observed and what outcomes the observer is looking for
-- and unknown association between factors and outcomes --
such as not accounting for other reasons that could account
for the observed result in a given group of patients.
The value of these types of studies (e.g., case series,
ecologic, case-control, cohort) is that they provide
preliminary evidence that can be used as the basis for
hypotheses in stronger experimental studies, such as
randomized controlled trials.
Consider the recent HRT report finding that using estrogens
increases the risk of heart disease and cancers. The
hypothesis that it might reduce these risks was based on
observations that were proven to be incorrect.
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About press releases, and the reports
you don't see:
Protocols, ethical principles, and a desire to maintain
credibility are beneficial forces that encourage responsible
public reporting of drug development research and clinical
trial outcomes. But consider that an easy way to put a
positive spin on a company's drug development project is to
report or leak to the press only the reports with favorable
outcomes, and to keep less than stellar results from being
released at all. Ask yourself: How is response being
defined? How were the patients selected?
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Anecdotes (Least reliable)
These are informal reports that may or may not come from
direct observation. Anecdotes may be useful as
starting points for future inquires, but they are often the
source of misleading information as well. It can be
dangerous, wasteful, or both to base decisions on anecdotes
for many reasons including, but not limited to, the
following:
-
The
possible biases - and sometimes the unknown or
questionable credentials -- of the individuals making
the report or claim;
-
Anecdote will lack details about the specifics of the
case, such as natural course of the disease, how
responses were measured, and information about the
ultimate outcome -- such as how the intervention
affected survival;
-
This
type of report typically uses vague language to report
benefit, such as "response." See above.
-
The
anecdote will often be based on assessments of response
without use of objective tools, and without review from
disinterested 3rd parties, such as the FDA. It will also
fail to provide details about the duration of the
response, and the overall clinical benefit.
-
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Anecdotes often confuse
cause and effect. For example, "I took zinc and
my bad breath increased or decreased." In this
example, there are a host of other factors that
could account for the change, therefore the
association cannot be made, credibly. |
-
Drawback
of anecdotes (personal accounts), by example:
Jane
recently asked Jim what weather to expect in New York on
October 1st. Jim reports that it was 25
degrees when he went last year on that date.
We know
that Jim's account does not predict next year's weather
on that day in New York, because we have lots of
experience with temperature and weather. At best it's a
reference point on what's possible.
Examining Jim's report closely it may occur to us that
Jim didn't mention where he was in New York, at what
elevation, and at what time of day he took the reading
... Therefore, we don't have other important
variables that can tell us how likely his experience is
to predict ours.
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In-vivo or in-vitro?
We frequently read or hear about the anti-cancer properties
of this or that supplement based on scientific research
findings. Here are some questions to ask of this kind
of information:
-
Was the
response detected in a test tube (in-vitro)?
The
human body is infinitely more complex than a test tube.
Nevertheless, indications of activity in a test tube
often become the basis for product claims about natural
supplements. Be aware that this can only be a
starting point for additional experiments. Using such
data as the basis of medical claims is irresponsible,
and bias should be suspected. Furthermore, you
might ask if the dose used to produce the in-vitro
effect possible to achieve in the body, or can it be
achieved safely?
-
Animal studies?
Is the claim for the promise of a drug or supplement based
solely on animal studies? While animals are useful for
preclinical testing of new drugs, there are many differences
between animals and humans; and drugs that show promise in
animals do not always work or work safely in humans.
Junk Science: How Politicians, Corporations, and Other Hucksters
Betray Us (Hardcover)
Junk Science Judo: Self-Defense against Health Scares and Scams
(Hardcover)
unSpun: Finding Facts in a World of Disinformation (Paperback)
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