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Weight Loss Patent Abstract
A method is provided for identifying a patient as being suitable
for implantation of a weight-loss assist device. The method includes
identifying the patient as being generally suitable for the implantation
and subsequently, measuring a value associated with the patient.
Responsively to determining that the value is beyond a threshold
associated therewith, the weight-loss assist device is implanted.
Weight Loss Patent Claims
1. A method for identifying a patient as being suitable for implantation
of a weight-loss assist device, comprising: identifying the patient
as being generally suitable for the implantation; subsequently,
measuring a value associated with the patient; and responsively
to determining that the value is beyond a threshold associated therewith,
implanting the weight-loss assist device.
2. The method according to claim 1, wherein measuring the value
comprises measuring a rate of gastric emptying.
3. The method according to claim 1, wherein identifying the patient
as being generally suitable comprises performing a physical examination
and evaluating a medical history of the patient.
4. The method according to claim 1, wherein measuring the value
comprises a level of weight loss.
5. The method according to claim 4, wherein measuring the level
of weight loss comprises placing the patient n diet counselling.
6. A method for identifying a patient as being suitable for implantation
or a weight-loss assist device, comprising: determining a weight
of the patient at first and second times; determining whether a
level of weight loss of the patient from the first time to the second
time exceeds a weight loss threshold; and responsively to determining
that the level of weight loss does exceed the weight loss threshold
implanting the weight-less assist device.
7. The method according to claim 6, wherein determining whether
the level weight loss exceeds the weight loss threshold comprises
identifying a weight loss reduction corresponding to an excess weight
loss of at least 3% during a period lasting between 3 and 6 weeks.
8. A method for identifying a patient as being suitable for implantation
of a weight-loss assist device comprising: measuring a gastric emptying
rate of the patient; determining whether the gastric emptying rate
exceeds a gastric emptying, rate threshold; and responsively to
determining that the gastric emptying rate does exceed the gastric
emptying rate threshold, implanting the weight-loss assist device.
9. The method according to claim 8, wherein determining whether
the gastric emptying rate exceeds the gastric emptying rate threshold
comprises identifying a gastric emptying, rate corresponding to
a level of gastric retention at two hours of less than 40%.
10. The method according to claim 8, wherein determining whether
the gastric emptying rate exceeds the gastric emptying rate threshold
comprises identifying a gastric emptying rate corresponding to a
level of gastric retention at two hours of less than 30%.
11. The method according to claim 8, wherein determining whether
the gastric emptying rate exceeds the gastric emptying rate threshold
comprises identifying a gastric emptying rate corresponding to a
gastric half-emptying time of less than 110 minutes.
12. The method according to claim 8, comprising: determining a
weight of the patient at first and second times; and determining
whether a level of weight loss of the patient from the first time
to the second time exceeds a weight loss threshold, wherein implanting
the weight-loss assist device comprises implanting the weight-loss
assist device responsively to determining that the gastric emptying
rate exceeds the gastric emptying rate threshold and responsively
to determining that the level of weight loss exceeds the weight
loss threshold.
13. A method for identifying a patient as being suitable for implantation
of a weight-loss assist device, comprising: measuring a first rate
of gastric activity of the patient, prior to food intake by the
patient; measuring a second rate of gastric activity of the patient,
subsequently to the food intake; comparing a difference between
the first and second rates to a threshold; and in response to the
comparing, implanting the weight-loss assist device.
14. The method according to claim 13, wherein comparing comprises
determining whether the difference is above a threshold.
15. The method according to claim 13, wherein comparing comprises
determining whether the difference is below a threshold.
16. The method according to claim 15, wherein determining comprises
subtracting one of the rates from the other rate.
17. The method according t claim 15, wherein determining comprises
calculating a ratio of the rates.
18. The method according to claim 15, wherein determining comprises
setting the threshold to be greater than 40%.
19. The method according, to claim 15, wherein determining comprises
setting; the threshold to be less than 40%.
20. The method according to claim 15, wherein determining comprises
setting the threshold to be greater than 5%.
21. The method according to claim 15, wherein determining comprises
setting the threshold to be between 5% and 40%.
22. The method according to claim 15, wherein determining comprises
setting the threshold to be between 15% and 25%.
23. The method according to claim 15, wherein measuring the first
and second rates of gastric activity comprises measuring first and
second rates of propagating slow waves, respectively.
24. The method according to claim 15, wherein measuring the first
and second rates comprises measuring the rates non invasively.
25. The method according to claim 15, wherein measuring the first
and second rates comprises measuring the rates invasively.
26. The method according, to claim 15, wherein measuring the first
and second rates comprises temporarily coupling a measurement electrode
to a gastric muscle of the patient.
27. A method for identifying a patient as being suitable for implantation
of a weight-loss assist device, comprising: measuring a first rate
of gastric activity of the patient; subsequently, applying electrical
stimulation to the patient; subsequently, measuring a second rate
of gastric activity of the patient; determining whether a difference
between the first and second rates is above a threshold; and in
response to determining that the difference is the threshold, implanting
the weight-loss assist device.
28. The method according, to claim 27, wherein measuring the first
and second rates of gastric activity comprises measuring, first
and second rates of propagating slow waves, respectively.
29. The method according to claim 27, wherein measuring the first
and second rates comprises temporarily coupling a measurement electrode
to a gastric muscle of the patient.
30. The method according to claim 27, wherein applying electrical
stimulation to the patient comprises temporarily coupling a measurement
electrode to a gastric muscle of the patient.
31. The method according to claim 27, wherein determining comprises
subtracting one of the rates from other rate.
32. The method according to claim 27, wherein determining comprises
calculating a ratio of the rates.
33. The method according to claim 27, wherein determining comprises
setting the threshold to be less than 20%.
34. The method according to claim 27, wherein determining comprises
setting the threshold to be between 20% and 40%.
35. The method according to claim 27, wherein determining comprises
setting the threshold to be greater than 40%.
Weight Loss Patent Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S. Provisional
Patent Application 60/728,658 to Haddad et al., filed Oct. 20, 2005,
entitled "Patient; selection method for obesity treatment."
which is assigned to the assignee of the present patent application
and is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to assisting weight
loss, and specially to screening procedures for determining a patient's
suitability for implantation of a weight-loss assist device.
BACKGROUND OF THE INVENTION
[0003] Obesity is a difficult to treat chronic condition defined
by a body mass index (BMI=mass/height.sup.2[kg/m]) greater than
30. For obese persons, excessive weight is commonly associated with
increased risk of cardiovascular disease, diabetes, degenerative
arthritis, endocrine and pulmonary abnormalities, gallbladder disease
and hypertension. Additionally, such persons are highly likely to
experience psychological difficulties because of lifestyle restrictions
such as reduced mobility and physical capacity, due to back pain
joint problems, and shortness of breath. In severe cases, this can
contribute to absenteeism and unemployment. Moreover, impairment
of body image can lead to significant psychological disturbances.
Repeated failures of dieting and exercise to resolve the problem
of obesity can result in feelings of despair and the development
of clinical depression.
[0004] U.S. Pat. No. 6,600,953 to Flesler et al., which is assigned
to the assignee of the present patent application and is incorporated
herein by reference, describes apparatus for treating a condition
such as obesity. The apparatus includes a set of one or more electrodes,
which are adapted to be applied to one or more respective sites
in a vicinity of a body of a stomach of a patient. A control unit
is adapted to drive the electrode set to apply to the body of the
stomach a signal, configured such that application thereof increases
a level of contraction of muscle tissue of the body of the stomach,
and decreases a cross-sectional area of a portion of the body of
the stomach for a substantially continuous period greater than about
3 seconds.
[0005] U.S. Pat. No. 6,571,127 and PCT Patent Publication WO 99/03533
to Ben-Haim et a., which are incorporated herein by reference, describe
apparatus and methods for applying signals to smooth muscle so as
to modify the behavior thereof. In particular, apparatus for controlling
the stomach is described in which a controller applies an electrical
field to, electrodes on the stomach wall so as to modify the reaction
of muscle tissue therein to an activation signal, while not generating
a propagating action potential in the tissue. In the context of
the present patent application and in the claims, the use of such
a non-excitatory signal to modify the response of one or more cells
to electrical activation thereof without inducing action potentials
in the cells, is referred to as Excitable-Tissue Control (ETC).
Use of an ETC signal is described with respect to treating obesity,
by applying the ETC signal to the stomach so as to delay or prevent
emptying of the stomach. In addition, a method is described for
increasing the motility of the gastrointestinal tract, by applying
an ETC signal to a portion of the tact in order to increase the
contraction force generated in the portion and the stretching of
nearby tissue.
[0006] U.S. Patent Application Publication 2004/0147816 to Policker
et al., which is assigned to the assignee of the present patent
application and is incorporated herein by reference, describes diet
evaluation gastric apparatus, which detects when a patient swallows,
and detects the type and amount of matter ingested. The apparatus
includes electrodes adapted to be coupled to the fundus and antrum
of the patient and to measure electrical and mechanical activity
therein, and a control unit to analyze such electrical and mechanical
activity and optionally apply electrical energy to modify the activity
of tissue of the patient.
[0007] In an article by Tougas et al., entitled, "Assessment
of gastric emptying using a low fat meal: Establishment of international
control values, " American Journal of Gastroenterology, 95(6),
2000, pp. 1456-1462, which is incorporated herein by reference,
a study is described in which a simplified scintigraphic measurement
of gastric emptying was compared to coventional gastric scintigraphic
techniques and normal gastric emptying values defined in healthy
subjects.
[0008] An article by Choli et at., entitled, "[.sup.13C] Octanoic
acid breath test for gastric emptying of solids: Accuracy, reproducibility,
and comparison with scintigraphy," Gastroenterology, 112, 1997,
pp. 1155-1162, which is incorporated herein by reference, describes
a breath test using .sup.13C to measure gastric emptying of solids.
[0009] An article by English et at., entitled, "Food fails
to suppress ghrelin levels in obese humans, " J Clin Endocrinol
Metab, June 2002, 87(6): 2984-2987, which is incorporated herein
by reference, describes ghrelin as the first circulating hormone
shown to stimulate feeding in humans following systemic administration.
Food consumption was known to decrease circulating ghrelin concentrations
in lean subjects. The authors investigated the effects of a test
meal on plasma ghrelin and leptin cocentrations in 13 lean and 10
obese subjects. Fasting ghrelin was significantly higher in lean
than in obese subjects, and fell by 39.5% thirty minutes after eating
in the lean group before returning rapidly towards baseline values.
There was no change in circulating, ghrelin in the obese group.
Circulating leptin concentration also fell acutely 15 minutes following
food intake in lean but not obese subjects. The authors concluded
that (a) obese subjects do not exhibit the decline in plasma ghrelin
and leptin seen after a meal in the lean, and (b) the role of the
decline in leptin is unclear but given the orexigenic properties
of ghrelin, the lack of suppression following a meal in obese subjects
could lead to increased food consumption and suggests that ghrelin
may be involved in the patlhophysiology of obesity.
SUMMARY OF THE INVENTION
[0010] In some embodiments of the present invention, a patient
is identified who appears to be a generally-suitable candidate for
implantation of a weight-loss assist device. For example, a generally-suitable
candidate may be identified based on weight, height, age, and desire
to undergo the implantation procedure. Subsequently, once the candidate
has been identified as being generally suitable, one or more further
tests are performed in order to determine whether the candidate
is in: (a) a first population, which includes patients who are likely
to benefit from the implantation of the device, or (b) a second
population, which includes patients who are not likely to derive
substantial. benefit from the implantation
[0011] An example of a benefit derived from the device is defined
by at least a threshold amount of weight loss following activation
of the implanted device, compared to the patient's pre-implantation
weight. In an embodiment, the threshold weight loss is a level of
excess weight loss (EWL) of about 10% attained during a time period
of about 6-20 weeks. Alternatively, benefit is defined using thresholds
of EML equal to about20%, 30%, or 40%. Alternatively, is additionally,
a benefit derived from the device is expressed using a measure other
than weight loss, such as, for example, improved control of blood
sugar or another blood component, improved self-reported body image,
or an improved cardiovascular parameter.
[0012] In accordance with an embodiment of the present invention,
patients are determined to be in the first or second population
based upon a rate of gastric emptying. Typically, if the rate of
gastric emptying is faster than a threshold, ten the patient is
determined to be likely to benefit from implantation of the device.
For example, if the patient's gastric half-emptying time is less
than about 80, 90, or 100 minutes, then the patient may be determined
to be likely to benefit from implantation. Alternativey or additionally,
if the level of gastric retention at two hours is less than about
20%, 30%, or 40%, then the patient may be determined to be likely
to benefit from implantation.
[0013] In accordance with an embodiment of the present invention,
a patient who is identified as being a generally-suitable candidate
is placed into an evaluation program. During the evaluation program,
the patient is weighed and counseled regarding changes in diet an/or
lifestyle which are likely to help produce weight loss. Alternatively,
the patient is not counseled, but is tracked during the evaluation
period. At a later points (e.g., about 2-6 weeks o) about 6-20 weeks
following counselling or initiation of tracking), the patient's
weight is measured again. An excess weight loss greater than, for
example, about 2%, 2.5%, 2.75%, or 3% is used to determine that
the patient is likely to benefit from implantation.
[0014] In an embodiment, a weighted or non-weighted combination
score is derived based on fast gastric emptying and weight loss
during the evaluation period. For some applications the combination
score allows patients whose gastric emptying rate is not sufficient
to justify implantation to nevertheless have the device implanted
if weight loss during the evaluation period is sufficiently high.
Alternatively or additionally, the combination score allows patients
whose weight loss during the evaluation period is not sufficient
to justify implantation to nevertheless have the device implanted
if the gastric emptying rate is sufficiently high.
[0015] In an embodiment, a patient is expected to have both a threshold
gastric emptying rate and a threshold weight loss during the evaluation
period in order to be determined to be likely to benefit from implantation.
[0016] There is therefore provided, in accordance with an embodiment
of the invention, a method for identifying a patient as being suitable
for implantation of a weight-loss assist device, including:
[0017] determining a weight of the patient at first and second
tires;
[0018] determining whether a level of weight loss of the patient
from the first time to the second time exceeds a weight loss threshold;
and
[0019] responsively to determining that the level of weight loss
does exceed the weight loss threshold, implanting the weight-loss
assist device.
[0020] In an embodiment, determining whether the level of weight
loss exceeds the weight loss threshold includes identifying a weight
loss reduction corresponding to an excess weight loss of at least
3% during a period lasting between 3 and 6 weeks.
[0021] There is further provided, in accordance with an embodiment
of the invention, a method for identifying a patient as being suitable
for implantation of a weight-loss assist device, including:
[0022] measuring a gastric emptying rate of the patient;
[0023] determining whether the gastric emptying rate exceeds a
gastric emptying rate threshold; and
[0024] responsively to determining that the gastric emptying rate
does exceed the gastric emptying rate threshold, implanting the
weight-loss assist device.
[0025] In an embodiment, determining whether the gastric emptying
rate exceeds the gastric emptying rate threshold includes identifying
a gastric emptying rate corresponding to a level of gastric retention
at two hours of less than 40%.
[0026] In an embodiment, determining whether the gastric emptying
rate exceeds the gastric emptying rate threshold includes identifying
a gastric emptying rate corresponding to a level of gastric retention
at two hours of less than 30%.
[0027] In an embodiment, determining whether the gastric emptying
rate exceeds the gastric emptying rate threshold includes identifying
a gastric emptying rate corresponding to a gastric half-emptying
time of less than 110 minutes.
[0028] In a embodiment, the method includes:
[0029] determining a weight of the patient at first and second
times; and
[0030] determining whether a level of weight loss of the patient
from the first time to the second time exceeds a weight loss threshold,
[0031] wherein implanting the weight-less assist device includes
implanting the weight-loss assist device responsively to determining
that the gastric emptying rate exceeds the gastric emptying rate
threshold and responsively to determining that the level of weight
loss exceeds the weight loss threshold.
[0032] There is still further provided, in accordance with an embodiment
of the invention, a method for identifying a patient as being suitable
for implantation of a weight-loss assist device, including:
[0033] identifying the patient as being generally suitable for
the implantation;
[0034] subsequently, measuring a value associated with the patient;
and
[0035] responsively to determining that the value is beyond a threshold
associated therewith, implanting the weight-loss assist device.
[0036] In an embodiment, measuring the value includes measuring
a rate of gastric emptying.
[0037] In an embodiment, identifying the patient as being generally
suitable includes performing a physical examination and evaluating
a medical history of the patient.
[0038] In an embodiment, measuring the value includes measuring
a level of weight loss.
[0039] In an embodiment, measuring the level of weight loss includes
placing the patient in diet counseling.
[0040] There is also provided, in accordance with an embodiment
of the invention, a method for identifying a patient as being suitable
for implantation of a weight-loss assist device, including:
[0041] identifying the patient as being generally suitable for
the implantation;
[0042] subsequently, measuring a value associated with the patient;
and
[0043] responsively to determining that the value is beyond a threshold
associated therewith, implanting the weight-loss assist device.
[0044] There is additionally provided, in accordance with an embodiment
of the invention a method for identifying a patient as being suitable
for implantation of a weight-loss assist device, including:
[0045] determining a weight of the patient at first and second
times;
[0046] determining whether a level of weight loss of the patient
from the first time to the second time exceeds a weight loss threshold;
and
[0047] responsively to determining that the level of weight loss
does exceed the weight loss threshold, implanting the weight-loss
assist device.
[0048] There is still additionally provided, in accordance with
an embodiment of the invention, a method for identifying a patient
as being suitable for implantation of a weight-loss assist device,
including:
[0049] measuring a gastric emptying rate of the patient; determining
whether the gastric emptying rate exceeds a gastric emptying rate
threshold; and
[0050] responsively, to determining that the gastric emptying rate
does exceed the gastric emptying rate threshold, implanting the
weight-loss assist device.
[0051] There is yet additionally provided, in accordance with an
embodiment of the invention, a method for identifying a patient
as being suitable for implantation of a weight-loss assist device,
including:
[0052] measuring a first rate of gastric activity of the patient,
prior to food intake by the patient,
[0053] measuring second rate of gastric activity of the patient,
subsequently to the food intake;
[0054] comparing a difference between the first and second rates
to a threshold; and
[0055] in response to the comparing, implanting the weight-loss
assist device.
[0056] In an embodiment, comparing includes determining whether
the difference is above a threshold.
[0057] In an embodiment, comparing includes determining whether
the difference is below a threshold.
[0058] In an embodiment, determining includes subtracting one of
the rates from the other rate.
[0059] In an embodiment, determining includes calculating a ratio
of the rates.
[0060] In an embodiment, determining includes setting the threshold
to be greater than 40%.
[0061] In an embodiment, determining includes setting the threshold
to be less than 40%.
[0062] In an embodiment, determining includes setting the threshold
to be greater than 5%.
[0063] In an embodiment, determining includes setting the threshold
to be between 5% and 40%.
[0064] In an embodiment, determining includes setting the threshold
to be between, 15% and 25%.
[0065] In an embodiment, measuring the first and second rates of
gastric activity includes measuring first and second rates of propagating
slow waves, respectively.
[0066] In an embodiment, measuring the first and second rates includes
measuring the rates non invasively.
[0067] In an embodiment, measuring, the first and second rates
includes measuring the rates invasively.
[0068] In an embodiment, measuring the first and second rates includes
temporarily coupling a measurement electrode to a gastric muscle
of the patient.
[0069] There is also provided, in accordance with an embodiment
of the invention, a method for identifying a patient as being suitable
for implantation of a weight-loss assist device, including:
[0070] measuring a first rate of gastric activity of the patient;
[0071] subsequently, applying electrical stimulation to the patient;
[0072] subsequently, measuring a second rate of gastric activity
of the patient;
[0073] determining whether a difference between the first and second
rates is above threshold; and
[0074] in response to determining that the difference is the threshold,
implanting the weight-loss assist device.
[0075] In an embodiment, measuring the first and second rates of
gastric activity includes measuring first and second rates of propagating
slow waves, respectively.
[0076] In an embodiment, measuring the first and second rates includes
temporarily coupling a measurement electrode to a gastric muscle
of the patient.
[0077] In an embodiment, applying electrical stimulation to the
patient includes temporarily coupling a measurement electrode to
a gastric muscle of the patient.
[0078] In an embodiment, determining includes subtracting one of
the rates from the other rate.
[0079] In an embodiment, determining includes calculating a ratio
of the rates.
[0080] In an embodiment, determining includes setting the threshold
to be less than 20%.
[0081] In an embodiment, determining includes setting the threshold
to be between 20% and 40%.
[0082] In an embodiment, determining includes setting the threshold
to be greater than 40%.
[0083] The present invention will be more fully understood from
the following detailed description of embodiments thereof, taken
together with the drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0084] FIG. 1 is a flow chat showing a method for selecting patients,
in accordance with an embodiment of the present invention;
[0085] FIGS. 2 and 3 are graphs showing gastric emptying rate data
for two sets of patients, acquired and analyzed in accordance with
an embodiment of the present invention;
[0086] FIG. 4 is a graph showing weight loss data for two sets
of patients, acquired and analyzed in accordance with an embodiment
of the present invention;
[0087] FIG. 5 is a graph showing excess weight loss in multiple
patients as a function of gastric emptying rate, acquired and analyzed
in accordance with an embodiment of the present invention;
[0088] FIG. 6 is a graph showing weight loss curves for different
patient populations, acquired and analyzed in accordance with an
embodiment of the present invention; and
[0089] FIGS. 7-11 are additional graphs showing respective selection
criteria and their relationship to the different patient populations,
acquired and analyzed in accordance with respective embodiments
of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0090] FIG. 1 is a flow chart showing a method for identifying
patients who are suitable to have a weight-loss assist device implanted,
in accordance with an embodiment of the present invention, As is
shown in the flow chart, a patient who wants to lose weight requests
to enroll, and initial screening determines whether the patient
is a generally-suitable candidate for implantation of the weight-loss
assist device. For example, a generally-suitable candidate may be
identified based on weight, height, age, and desire to undergo the
implantation procedure. Unsuitable candidates are not permitted
to enroll, but may be encouraged to seek other forms of treatments
(e.g., ongoing diet and lifestyle counselling). Candidates who are
identified as being generally suitable are enrolled in an evaluation
program, in which one or more tests are performed in order determine
whether the candidate is in: (a) a first population, which includes
patients who are likely to benefit from the implantation of the
device, or (b) a second population, which includes patients who
are not likely to derive substantial benefit from the implantation.
[0091] In the first stage of the evaluation program, as show in
FIG. 1, the patient is weighed, and counseled regarding changes
in diet and/or lifestyle which are likely to help produce weight
loss. At a later point (e.g., about 2-6 weeks or about 6-20 weeks
following counselling or initiation of counselling), the patient's
weight is measured again. An excess weight loss greater than a threshold
between about 2% and about 3% (such as, for example, about 2%, 2,5%,
2.775%, or 3%) is used to determine that the patient is likely to
benefit from implantation. In an embodiment, the, threshold is less
than 2% (e.g., it is between 0.1% and 2%), or greater than 3% (e.g.,
it is between 3% and 5%). For some applications, the weight loss
threshold is expressed as a rate of weight loss (e.g., a threshold
of about 0.1-5% EWL/month, typically a threshold of 0.5-1.5% EWL/month).
[0092] Patients who do not lose at least the threshold amount of
weight are typically rejected as candidates for implantation of
the weight-less assist device. Alternatively, the lack of sufficient
weight loss during the first stage of the evaluation program is
used as an indicator against the implantation, but does not, in
and of itself, result rejection of the patient as a candidate for
implantation.
[0093] Subsequently, some or all of the patients undergo testing
of gastric emptying rate. For some applications, techniques for
measuring gastric emptying are utilized that are described in the
above-referenced article by Tougas et al. and/or the above-referenced
article by Choi et al., which are incorporated herein by reference.
Typically, if the rate of gastric emptying is faster than a threshold,
then the patient is determined to be likely to benefit from implantation
of the device. For example, if the patient's gastric half-emptying
time is less than about 80, 90, or 100 minutes, then the patient
may be determined to be likely to benefit from implantation. Alternatively
or additionally, if the level of gastric retention at two hours
is less than about 20%, 30%, or 40% then the patient may be determined
to be likely to benefit from implantation.
[0094] Typically, but not necessarily, the gastric emptying threshold
rate is in a range which is considered to be a generally normal
emptying rate for healthy people (e.g., 10-50% retention at two
hours and/or t1/2 of 30-100 minutes). Thus, it may be that some
patients with non-pathological gastric emptying rates are rejected
as candidates for implantation of the weight-loss assist device.
[0095] It is noted that although FIG. 1 shows a requirement of
both above-threshold weight loss and above-threshold gastric emptying
rate in order to determine that a patient is a suitable candidate
for implantation of the weight-loss assist device, the scope of
the present invention includes performing only one of these tests,
or combining the tests using a weighting function.
[0096] In addition to or instead of the tests for weight loss and
gastric emptying rate described hereinabove the scope of the present
invention includes identifying one or more of the following in order
to facilitate an identification of a patient as a suitable candidate
for having a weight-loss assist device implanted:
[0097] prolonged history of excess weight, such as from about 11-40
years, e.g., greater than 15, 18, or 20 years,
[0098] type of obesity (e.g., peripheral),
[0099] quality of if questionnaire scores, such as a RAND-36 test
showing a pain factor score above 70, 75, or 80,
[0100] scores on the three actor eating questionnaire (TFEQ) (e.g.,
cognitive control score range between 1 and 20, for example, less
than about 9, or between about 4 and about 8 or 9), initial weight
(e.g., range of 80-130 kg, or a range between about 100 and about
120 or 125 kg), and
[0101] socioeconomic conditions (e.g., patients with greater motivation
or social support structures to maintain lifelong weight control).
[0102] FIGS. 2 and 3 are graphs showing gastric emptying rate data
for two sets of patients, acquired and analyzed in accordance with
an embodiment of the present invention. In this study, a weight-loss
assist device was implanted in 16 patients. (Data shown in FIGS.
2 and 3 represent results from 15 of the patients; gastric emptying
rate data for the 16 the patient are missing due to a technical
problem.).
[0103] The weight-loss assist device comprised a set of electrodes
implantable on the funds, a set of electrodes implantable on the
antrum, and a control unit. The control unit received data from
the fundic electrodes indicative of stretching of the fundus, and
data from the antral electrodes indicative of changes in the rate
of slow wave propagation. The control unit analyzed the data from
both sets of electrodes, and determined whether there was a high
likelihood that a meal was being eaten. Upon such a determination,
the control unit drove the antral electrodes to apply an ETC signal
as a pulse train immediately following, detected gastric electrical
activity. In general, a pulse train frequency of approximately 40-120
Hz is believed to be particularly suitable, and in this study the
frequency was approximately 80 Hz. The duration of ETC pulse trains
(or DC signals) is generally optimal if between approximately 500
and 2500 ms, and the duration of the ETC pulse trains in is study
was typically approximately 1200 ms. Peak-to-Peak ETC signal amplitudes
between approximately +/-6 mA and +/-16 mA, typically from +/-8
mA to +/-12 mA were applied. The applied signal tends to reduce
eating in many patients.
[0104] In this study, measurements were taken regarding the rate
of gastric emptying three weeks following implantation, but prior
to initiating weight-loss treatment by applying a signal the stomach
of each patient. A range of gastric emptying rates was identified,
most of which being gastric half-emptying times from 60 to 120 minutes,
and levels of retention at two hours from 15%/ to 45%. It is noted
that this range of gastric emptying rates is generally considered
normal.
[0105] The weight-loss assist device was activated six weeks after
implantation. Patients' weights and overall health were monitored.
At 20 weeks post-implantation, patients were divided into two groups
based on weight loss compared to pre-implantation, weight. Patients
whose excess weight loss was greater than 10% were assigned to group
A. Patients whose EWL was less than 10% were assigned to group B.
[0106] The pre-activation gastric emptying rates of the patients
in both groups were retrospectively analyzed, and these results
are shown in FIGS. 2 and 3. It is seen that patients who lost more
weight (group A) had significantly higher gastric emptying rates
than those in group B, who lost less weight (p<0.01,t-test).
[0107] It is noted that the rates of gastric emptying for all patients
in the study were within the normal range, and that patients in
group B ("slow" gastric emptying rate patients) were all
asymptomatic with respect to their gastric emptying rates.
[0108] FIG. 4 is a graph showing weight loss data for the 16 patients
in groups A and B, acquired and analyzed in accordance with an embodiment
of the present invention. Six weeks after implantation of the weight-loss
assist device, but prior to activation of the device to initiate
weight-loss treatment, the weight of each patient was measured,
and these weight results are shown in FIG. 4. Patients in group
A are seen to tend to have higher excess weight loss than patients
in group B at week 6. Patients in group A had significantly greater
excess weight loss than patients in group B after 14 weeks A therapy
with the weight-loss assist device, i.e., at week 20 post-implantation
(p <0.01). In other words, patients who eventually would lose
more than 10% of their excess weight after 14 weeks of therapy could
generally be identified retrospectively, based on their weight loss
due to diet counselling.
[0109] FIG. 5 is a graph showing excess weight loss in the above-described
15 patients as a function of gastric emptying rate three weeks following
implantation, but prior to initiating weight-loss treatment, acquired
and analyzed in accordance with an embodiment of the present invention.
(As noted above, gastric emptying rate data for the 16the patient
are missing due to a technical problem.) It is seen that 5 out of
6 patients having less than 25% retention at 2 hours lost more than
10% of their excess weight after 14 weeks of therapy. Additionally,
8 out of 9 patients having more than 25% retention at 2 hours lost
less than 10% of their excess weight after 14 weeks of therapy.
[0110] FIG. 6 is a graph showing weight loss curves for different
patient populations, acquired and analyzed in accordance with an
embodiment of the present invention. In particular, FIG. 6 shows
the percent excess weight loss that would have been achieved had
the patients in this study been screened using one of the following
screening procedures provided in accordance with some embodiments
of the present invention:
[0111] Procedure I: Screen for (a) at week 6, EWL, greater than
3%, and (b) at week 3, meal retention at two hours less than 35%,
[0112] Procedure II: Screen for EWL, at week 6 greater than 3%,
and
[0113] Procedure III: Screen at week 3 for meal retention at two
hours less than 35%.
[0114] Procedure X: For comparison, weight loss for patients who
would have been rejected according to Procedures I and II is shown
in FIG. 6, as well.
[0115] FIG. 7-11 are additional graphs showing respective selection
criteria and their relationship to different patient populations,
acquired and analyzed in accordance with respective embodiments
of the present invention. The 16 patients described hereinabove
are a subset of a group of 33 patients. The study on the additional
17 patients was initiated after that described hereinabove with
respect to the 16 patients, FIGS. 7, 8, and 10 show results with
respect to the group of 33 patients. FIGS. 9 and 11 are graphs showing
data with respect to the 16 patients. (Tests described hereinbelow
with reference to FIGS. 9 and 11 were only performed on the 16 patients.)
[0116] FIGS. 7 is a graph showing the results of analyzing the
group of 33 patients in whom the weight loss assist device described
hereinabove was implanted. "Non-responders" (n=11) were
classified as those with an EWL of less than 5% at 8 weeks after
initiation of therapy. "Moderate responders" (n=5) were
those with an EWL between 5% and 10%. "Responders" (in=17)
were those with an EWL, greater than 10%.
[0117] It is seen that responders tended to have been overweight
for a longer time than non-responders and moderate responders. In
an embodiment of the present invention, a longer duration of a patient's
excess weight is used as a positive indicator for implantation of
a weight-loss assist device. For example, durations greater than
10, 15, 20, or 25 years may be used to indicate in favor of implantation.
Alternatively or additionally, a weighted scale may be applied in
the decision process, favoring implantation in accordance with increasing
duration of a patient's excess weight.
[0118] FIG. 8 shows results for the same patient groups (responders,
moderate responders, non-responders), with respect to the parameter
of obesity type Of the 33 patients represented in FIG. 8, fifteen
had peripheral obesity, and eighteen had central obesity. FIG. 8
shows a general tendency towards higher responsiveness to therapy
by the weight-loss assist device in patients with peripheral obesity
compared to patients with central obesity. For example, 50% of patients
with peripheral obesity were found to be responders, while 31% patients
with central obesity were found to be responders. Similarly, only
21% of patients with peripheral obesity were non-responders, while
44% of patients with central obesity were non-responders. In an
embodiment of the present invention, a patient's peripheral obesity
is a favorable indicator for implantation of a weight-loss assist
device.
[0119] FIG. 9 shows results in the 16 patents, with respect to
the parameter of the RAND-36 pain factor score. Responders tended
to have a higher score (avg.=83) than non-responders (avg.=71).
In an embodiment of the present invention a higher score on the
RAND-36 test with respect to pain (or similar results on a similar
test) is used as a favorable indicator for implantation of a weight-loss
assist device. For example, a score greater than 70, 75, or 80,
or a weighted analysis of the score, may be used as a favorable
indicator for implantation.
[0120] It noted that some embodiments described herein relate to
assessing patient pain and identifying the patient as being appropriate
for implantation of a weight-loss assist device in response to a
lower-than-threshold level of pain. For some applications, these
embodiments are supplemented or replaced by an evaluation of another
psychological and/or questionnaire-based factor, and identifying
the patient as being appropriate for implantation of the device
in response to an assessment that is "healthier" than
a threshold. Thus, other scales of the SF-36 may be used, or another
indicator of overall physical health, mental health, social acceptance,
etc.
[0121] FIG. 10 shows results for the group of 33 patients, with
respect to the parameter of cognitive control scale of the three
factor eating questionnaire (TFEQ). Responders tended to have lower
scores (avg.=7.1) than non-responders (avg.=9.3). In an embodiment,
TFEQ cognitive control scores of less than about 9, or between about
4 and about 8 or 9, are used as indicators favoring implantation
of a weight-loss assist device.
[0122] FIG. 11 is a graph comparing fasting ghrelin levels in patients
from Group A(n=5) and Group B (n=11), described hereinabove. The
patients in Group A, who had greater than 10% EWL, are seen to tend
to have higher ghrelin levels (avg.=761 ng/ml)4 than patients in
Group B (avg.=571 n/ml), p=0.09. In an embodiment, higher ghrelin
levels (e.g., greater than 500, 550, 600, 650, or 700 ng/ml) are
used as an indicator favoring implantation of a weight-loss assist
device.
[0123] A variety of tests are described herein for determining
the suitability of a patient for implantation of a weight-loss assist
device. It is noted that the scope of the present invention includes
performing only a single one of these tests, or combining two or
more of the tests using a weighting function. For example, a combination
score may be generated based on:
[0124] 2-hour gastric retention (GR)-1 point for 20% <GR<30%,
2 points for 5% <GR<=20%;
[0125] (b) excess weight loss 3-6 weeks 4 weeks) after initiating
counselling-1 point for 2% <EWL<3%, 2 points for 3% <=EWL<4%,
3 points EWL>4%;
[0126] (c) number of years of obesity-1 point for 15-20, 2 points
for greater than 20;
[0127] (d) type of obesity-1 point for peripheral;
[0128] (e) RAND)-36 pain factor score (PF)-1 point for 70<PF<75,
2 points for 75<=PF<80, and 3 points for PF>=80;
[0129] (f) cognitive control scale of the TFEQ-1 point for 7<=TFEQ<=8,
2 points for TFEQ<7; and
[0130] (g) fasting ghrelin levels (GL)-1 point for 600 ng/ml<GL<700
ng/ml, 2 points for GL>=700 ng/ml.
[0131] In an embodiment, patients with a combined score of at least
4 are accepted for implantation of a weight-loss assist device.
In some embodiments of the invention, patients with a combined score
of at least 6, 7, or 8 are accepted, while in other embodiments,
patients with a combined score of at least 3 are accepted. It is
to be understood that some elements of the combined score may be
eliminated from the list and the scoring mechanism modified accordingly.
Similarly, other elements may be added to the list and the scoring
mechanism modified accordingly.
[0132] It is noted that although techniques described hereinabove
relate to screening patients to determine whether they are suitable
for implantation of a weight-loss assist device that provides electrical
stimulation, the scope of the present invention includes using the
techniques described herein for screening patients to determine
their suitability for other invasive procedures, as well. For example,
these techniques may be used to determine a patient's suitability
for undergoing gastric banding or any other surgical procedure for
treating obesity. Similarly, the scope of the present invention
includes using, the screening techniques described hereinabove to
identify patients who would be most likely to benefit from implantation
of a diabetes-treatment device (e.g., that applies electrical stimulation
to the pancreas or gastrointestinal tract), instead of or in addition
to implantation of a weight-loss assist device.
[0133] For some applications, the screening procedures described
hereinabove are used to screen patients prior to implantation of
a device that employs techniques described in one or more of the
following references, which are described in the Background of the
present patent application and are incorporated herein by reference:
U.S. Pat. No. 6,600,953 to Flesler et al., U.S. Pat. No. 6,571,127
and PCT Patent Publication WO 99/03533 to Ben-Haim. et al., and
U.S. Patent Application Publication 2004/147816 to Policker et al.
[0134] It will be appreciated by persons skilled In the art that
the present invention is not limited to what has been particularly
shown and described hereinabove. Rather, the scope of the present
invention includes both combinations and subcombinations of the
various features described hereinabove, as well as variations and
modifications thereof that are not in the prior art, which would
occur to persons skilled in the art upon reading the foregoing description.
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