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A game theoretic approach to repeated foreign
body ingestion
Between January 2010 and February 2014,
a 39-year-old asthmatic woman with
borderline personality disorder, post-
traumatic stress disorder, and a history of
childhood sexual trauma was admitted to
our hospital system 61 times for foreign
body ingestion. During these hospitaliza-
tions, she underwent 62 upper endos-
copies. She also required two exploratory
laparotomies for surgical retrieval of a
pencil fragment and a battery that had be-
come obstructed in the small bowel. She
has swallowed pencils, portions of dispos-
able razors, knitting needles, metal nail
files, toothbrush handles, plastic pen frag-
ments, hair barrettes, disposable cutlery,
and AA batteries. All her admissions oc-
curred late in the evening or on weekends.
During the past 4-year time period, she
also underwent at least 28 additional
upper endoscopies at outside hospitals for
intentional foreign body ingestion. The
patient was assessed as being at high risk
for repeated self-harm. She engaged in
cognitive behavioral therapy, dialectical
behavioral therapy, and electroconvulsive
therapy, but her pattern of repetitive swal-
lowing remained unchanged.
A minority of patients is responsible for
the majority of intentional foreign body
ingestions with substantial economic
burden to hospitals [1, 2]. The interaction
between hospital and patient can be
phrased in terms of a nonzero sum game
between two adversaries [3, 4]. Two strate-
gic options are available to both the hospi-
tal and the patient. In ●
"Fig. 1 a, the four
outcomes associated with the two options
available to each adversary are arranged in
a two-by-two matrix. Each of the four en-
tries in the matrix contains two numbers.
The first number represents the prefer-
ence ranking of the hospital, and the sec-
ond number represents the preference
ranking of the patient. For instance, in
●
"Fig. 1 a, the upper left entry –2, + 2 re-
flects the (negative) loss to the hospital
through endoscopy, and the psychological
gain experienced by the patient through
foreign body ingestion and subsequent
medical treatment. The entry –3, + 1 in
the lower left cell represents a worse out-
come for the hospital, if the patient is not
managed immediately, and higher costs
accrue through additional medical adverse
events. The adverse events also diminish
the patient’s gain associated with a more
risky and complex medical encounter. As
reflected by the upper and lower cells in
the right column of ●
"Fig. 1 a, without
foreign body ingestion, no costs or benefits
accrue to hospital and the patient. From
the patient’s perspective, better outcomes
are always achieved by choosing the
strategy of foreign body ingestion irre-
spective of what the hospital subsequently
decides. From the hospital’s perspective,
endoscopy always represents the lesser
evil. Therefore, the game between hospital
and patient always ends with the outcome
of the upper left cell marked in red.
The hospital might consider spending
some money on providing the patient
with an incentive not to swallow foreign
objects. For instance, the hospital may
provide the patient with a paid hospital
position to alleviate her economic hard-
ship and social isolation, contingent on
the condition that she stops swallowing
foreign objects. Such a hypothetical sce-
nario is depicted by ●
"Fig. 1 b with its
changed lower row. If the patient contin-
ues to ingest foreign bodies in spite of the
incentive, the hospital would lose money
from the endoscopy and the wasted in-
centive. The patient may still experience
some psychological benefit from the
medical encounter, but would lose her
monetary reward. Such outcome is reflect-
ed by the –3, –1 entry of the lower left cell
in the revised game matrix shown in
●
"Fig. 1 b. If the patient accepts the in-
centive as being equivalent or even better
than the endoscopy encounters, the hos-
pital loses some money, but less than with
repetitive endoscopy (dependent on the
expenditure and type of incentive). Such
outcome is reflected by the –1, + 3 entry of
the lower right cell in●
"Fig. 1 b.
From the patient’s perspective, overall
better outcomes are now associated with
a strategy of no foreign body ingestion,
provided that the hospital also adheres to
its strategy of offering an incentive. The re-
vised game between hospital and patient
results in a new steady state marked in
red by the outcome of the lower right cell.
Using game theory and the principles of
contingency management, patients with
repetitive foreign body ingestion could be
offered an incentive to keep them from
swallowing foreign objects [4,5].
Endoscopy_UCTN_Code_CCL_1AB_2AF
Competing interests: None
Sarah J. Diamond, Amnon Sonnenberg
Portland VA Medical Center and Division
of Gastroenterology/Hepatology, Oregon
Health & Science University, Portland,
Oregon, USA
References
1Frei-Lanter CM,Vavricka SR,Kruger TH et al.
Endoscopy for repeatedly ingested sharp
foreign bodies in patients with borderline
personality disorder: an international sur-
vey. Eur J Gastroenterol Hepatol 2012; 24:
793 –797
2Huang BL,Rich HG,Simundson SE et al. In-
tentional swallowing of foreign bodies is a
recurrent and costly problem that rarely
causes endoscopy complications. Clin Gas-
troenterol Hepatol 2010; 8: 941 –946
3Straffin PD. Game theory and strategy.
Washington, DC: The Mathematical Associa-
tion of America; 1993
4Sonnenberg A. Personal view: the paradox of
runaway competitions in gastroenterology.
Patient
foreign
body
ingestion
–2, +2 0,0
0,0–3,+1
endoscopy
expectant
management
a
no
foreign
body
ingestion
Hospital
Patient
foreign
body
ingestion
–2, +2 0,0
–1, +3–3, –1
endoscopy
provide
incentive
b
no
foreign
body
ingestion
Hospital
Fig. 1 Game matrix of the interaction be-
tween hospital (row player) and patient (col-
umn player); abaseline scenario; bscenario
after introduction of incentive.
Cases and Techniques Library (CTL) E79
Diamond Sarah J, Sonnenberg A. Foreign body ingestion …Endoscopy 2015; 47: E79–E80
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Aliment Pharmacol Ther 2006; 23: 871 –
878
5Dutra L,Stathopoulou G,Basden SL et al. A
meta-analytic review of psychosocial inter-
ventions for substance use disorders. Am J
Psychiatry 2008; 165: 179 –187
Bibliography
DOI http://dx.doi.org/
10.1055/s-0034-1390920
Endoscopy 2015; 47: E79–E80
© Georg Thieme Verlag KG
Stuttgart · New York
ISSN 0013-726X
Corresponding author
Amnon Sonnenberg, MD, MSc
Portland VA Medical Center P3-GI
3710 SW US Veterans Hospital Road
Portland
OR 97239
USA
Fax: +1-503-220-3426
sonnenbe@ohsu.edu
Diamond Sarah J, Sonnenberg A. Foreign body ingestion …Endoscopy 2015; 47: E79–E80
Cases and Techniques Library (CTL)E80
Downloaded by: IP-Proxy CONSORTIUM:Harrass (Oregon HealthScience Univ), Oregon Health and Science University. Copyrighted material.
