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Focus and relevance in the management of GI bleeding
THINKING OUTSIDE THE BOX
Focus and relevance in the management of GI bleeding Amnon Sonnenberg, MD, MSc
Gastroenterologists vary in their patient management skills. Besides obvious differences in their knowledge base, procedural dexterity, and bedside manner, what else differentiates “good” from “bad” gastroenterologists? Two failures in particular seem to frequently characterize ineffective management skills. The first failure relates to the inability to establish a management goal that addresses the underlying medical problem. The primary problem may be only partly recognized or may be missed altogether and instead the goal of medical management becomes focused on a secondary problem or an unimportant side issue. As each diagnosis presents itself with multiple clinical symptoms, laboratory findings, and test results, a gastroenterologist may choose to manage a secondary symptom rather than the primary problem or underlying disease. Similarly, the correction of an abnormal laboratory test value or the pursuit of an intermediate outcome parameter could easily become the false foci of medical attention. The second failure relates to the inappropriate selection of test and procedural options to achieve the chosen management goal. A selected test procedure could be wrong because it is unable to yield any answers relevant to the management goal. Besides being blatantly wrong, a test could also be less effective because of its low sensitivity or specificity compared with other available tests. Medical pursuits may, thus, become inefficient for reasons associated with the first or second type of failure or even with both types combined, when a physician is simultaneously unable to focus on the right goal and also unable to assess the sequence of chosen interventions with regard to their goal relevance. Obviously, these types of failures apply to the management of any digestive disease. Because GI bleeding is a frequent issue of consults to gastroenterologists and because a large portion of GI endoscopy centers on diagnosis and treatment of GI bleeding, issues of focus and relevance frequently manifest themselves in the management of GI bleeding. Several examples are discussed in the following section to illustrate this point.
UNFOCUSED GOALS AND IRRELEVANT TESTS There are multiple examples of goals that are unfocused with respect to the primary medical problem. For instance, it is generally not recommended to excise www.giejournal.org
polyps during a colonoscopy performed for the workup of hematochezia. Unless they reach substantial size, the polyps are unrelated to the bleeding.1 The potential occurrence of postpolypectomy bleeding could further obfuscate the search for the primary bleeding site. It would be more appropriate to resolve the issue of hematochezia first and defer the polypectomy to a second colonoscopy at a later point in time. With respect to the primary problem of finding and treating the source of hematochezia, excising incidental polyps is a distraction. Similarly, in a patient with major GI bleeding, it would not be advisable to start GI endoscopy before cardiovascular resuscitation and stable hemodynamics have been achieved.2 The patient’s well-being and survival represent the primary medical problem. Finding and treating the bleeding lesion are ultimately only secondary goals in support of the primary goal. As a third example, consider a patient who presents with chronic watery diarrhea. Although on inspection the bowel movement appears watery brown, 1 of 3 fecal occult blood tests returns positive results. Frequent diarrhea can irritate the anal verge and cause minor bleeding from anal fissures or hemorrhoids.3 Obviously, the diagnostic workup should focus on finding and eliminating the cause of diarrhea rather than embarking on an endoscopic search for a potential GI bleeding site. Similarly, examples abound for irrelevant tests and endoscopic procedures with respect to managing GI bleeding. A test could simply represent a wrong choice for advancing the goal of diagnosing and treating the bleeding site. For instance, one would not start the workup for GI bleeding with a chest radiograph or magnetic resonance imaging of the head. In the same vein, a colonoscopy would not be the primary test to select for workup of hematemesis, nor would an EGD be the first procedure of choice for the workup of hematochezia. Besides the blatantly irrelevant tests, there are also procedural choices that do not miss their mark altogether, but still represent less-relevant options in pursuing the goal of finding and treating the bleeding lesion. In a patient with portal hypertension and maroon-colored stool, colonoscopy would represent only a secondary choice if the initial EGD failed to reveal a bleeding site. Similarly, after repeat EGDs and colonoscopies failed to reveal a bleeding site, yet another EGD would be considered a lesser option compared with CT angiography or capsule endoscopy. Volume 75, No. 4 : 2012 GASTROINTESTINAL ENDOSCOPY 861
Thinking outside the box
Sonnenberg
TABLE 1. 2 ⴛ 2 Matrices of the 3 relationships among test outcome, management goal, and underlying medical problem
Test-goal matrix (1)
EGD
Hematochezia Pos
Neg
Pos
20%
20%
Neg
80%
80%
(4)
Polypectomy
Colon polyps Pos
Neg
Pos
90%
5%
Neg
10%
95%
(7)
EGD
FOBT Pos
Neg
Pos
60%
40%
Neg
40%
60%
(10)
EGD
Goal-problem matrix
BII anemia
(2)
Hematochezia
UC flare Pos
Neg
Pos
60%
20%
Neg
40%
80%
(5)
Polyps
Hematochezia Pos
Neg
Pos
25%
25%
Neg
75%
75%
(8)
FOBT
(11)
Test-problem matrix
Diarrhea Pos
Neg
Pos
60%
30%
Neg
40%
70%
BII malnutrition
Pos
Neg
Pos
Neg
Pos
70%
30%
BII
Pos
70%
30%
Neg
30%
70%
Anemia
Neg
30%
70%
(3)
EGD
Neg
Pos
20%
20%
Neg
80%
80%
(12)
EGD
TP matrix, PPV
50%
50%
50%
50%
95%
50%
50%
60%
53%
50%
70%
58%
Hematochezia Pos
Neg
Pos
26%
26%
Neg
74%
74%
(9)
EGD
TG matrix, PPV
UC flare Pos
(6)
Polypectomy
Prior P
Diarrhea Pos
Neg
Pos
52%
46%
Neg
48%
54%
BII malnutrition Pos
Neg
Pos
58%
42%
Neg
42%
58%
Positive predictive value calculated using Bayes’ formula, for instance, in the case of matrix (9): 50% · 52%/(50% · 52% ⫹ (1 – 50%) · 46%) ⫽ 53%. UC, Ulcerative colitis; P, pretest probability; PPV, positive predictive value; Pos, positive; Neg, negative; FOBT, fecal occult blood test; BII, Billroth II partial gastrectomy.
FOCUS AND RELEVANCE IN TERMS OF SENSITIVITY AND SPECIFICITY The relationship between a test and the diagnosis or management goal can be phrased in terms of the conventional 2 ⫻ 2 matrix of true positive (sensitive), false positive, false negative, and true negative (specific) test results.4 The first example in Table 1 depicts the matrix of EGD in hematochezia. Endoscopy would be expected to yield a similar percentage of positive findings in subjects with or without hematochezia. Such a test would not raise the probability of having found the cause of hematochezia. This is indicated by the first positive predictive value in the second right-most column of the table, which is identical to the assumed prior probability of P ⫽ 50%. By contradistinction, colonoscopy with polypectomy is a highly sensitive and specific test for the diagnosis of polyps, as indicated by the fourth matrix of the table, capable of increasing the pretest (prior) probability from 50% to 95%. Similar to the test-goal matrix, one can phrase the relationship between management goal and actual problem in terms of a 2 ⫻ 2 matrix of sensitivity and specificity. The 862 GASTROINTESTINAL ENDOSCOPY Volume 75, No. 4 : 2012
fifth matrix of Table 1 describes the relationship between presence of colon polyps and hematochezia. Polyps would be found equally commonly among patients with or without hematochezia, indicating polypectomy to be a management goal that is unfocused with respect to the underlying medical problem of hematochezia. The 11th matrix depicts the relationship between anemia and general malnutrition in Billroth II partial gastrectomy. Anemia is depicted as a moderately sensitive and specific sign of malnutrition. The third set of matrices on the right side of Table 1 represents the test-problem matrices, depicting the relationships between test outcome and the actual medical problem. They are the product of multiplying the left with the middle set of matrices, that is, TP ⫽ TG ⫻ GP. (Such multiplication can be easily executed, for instance, on an Excel spreadsheet using its built-in MMULT function.5) The first row of matrices in Table 1 combines an irrelevant test with a moderately focused goal. The second row of matrices combines an excellent test with an unfocused goal. In both instances, the resulting test-problem matrix is characterized by 2 identical columns. As indicated by the corresponding positive predictive values in the far right www.giejournal.org
Sonnenberg
column, these 2 matrices would not be able to increase any pretest probability. In other words, any combination of an irrelevant test or an unfocused goal leaves the underlying medical problem unchanged because no headway can be made in affirming its presence. The third and fourth rows of matrices in Table 1 depict 2 examples in which moderately relevant tests were combined with moderately focused goals. The resulting test-problem matrices are far less efficient in increasing the pretest probability than any of its contributing matrices individually, highlighting the importance of combining a relevant test with a focused goal in pursuing a medical management problem.
CONCLUSION AND OUTLOOK For efficient resolution of GI bleeding, a gastroenterologist would need to stay focused on the underlying medical problem and choose the right sequence of test procedures relevant to achieving the treatment goal. Simple as these procedures may sound, physicians frequently fail to meet these 2 conditions. Preeminent among the reasons why medical pursuits fail are, first, a choice of wrong goals with respect to the underlying medical problem and, second, a choice of wrong tests with respect to the stated management goals. Focus on a wrong goal can potentially make the physician miss the underlying medical problem altogether and let it go unresolved. Choice of wrong test procedures delays reaching the aspired goals and, thus, renders the management process more dangerous and costly. Both types of error can contribute individually or jointly to poor management. As shown here, their joint contribution affects the overall outcome in a fashion that exceeds the negative influence of each error individually. To some extent, such errors can be avoided through training and experience. The workup of GI bleeding, how-
www.giejournal.org
Thinking outside the box
ever, is frequently initiated outside of gastroenterology through consult requests by critical or primary care physicians with only a limited understanding of the natural history of GI bleeding or the test characteristics of endoscopic procedures. Moreover, medical problems in general, and GI bleeding in particular, come in many disguises, which frequently defy the conditioned application of learned management patterns. Although this variety and novelty constitute the very appeal of clinical medicine, they also open the opportunity for endless failures and force the physician to focus on the right goals and relevant tests in each patient anew. DISCLOSURE The author disclosed no financial relationships relevant to this publication. REFERENCES 1. Zuckerman GR, Prakash C. Acute lower intestinal bleeding. Part II: etiology, therapy, and outcomes. Gastrointest Endosc 1999;49:228-38. 2. Yen D, Hu SC, Chen LS, et al. Arterial oxygen desaturation during emergent nonsedated upper gastrointestinal endoscopy in the emergency department. Am J Emerg Med 1997;15:644-7. 3. Friedman A, Chan A, Chin LC, et al. Use and abuse of faecal occult blood tests in an acute hospital inpatient setting. Intern Med J 2010;40:107-11. 4. Weinstein MC, Fineberg HV, Elstein AS, et al, eds. Clinical decision analysis. Philadelphia (Pa): WB Saunders; 1980. p. 75-130. 5. Bourg DM. Excel scientific and engineering cookbook. Sebastopol (Calif): O’Reilley Media; 2006. p. 225-6.
Portland VA Medical Center, Division of Gastroenterology/Hepatology, Oregon Health & Science University, Portland, Oregon, USA. Copyright © 2012 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 doi:10.1016/j.gie.2011.12.006
Volume 75, No. 4 : 2012 GASTROINTESTINAL ENDOSCOPY 863
Focus and relevance in the management of GI bleeding Amnon Sonnenberg, MD, MSc
Gastroenterologists vary in their patient management skills. Besides obvious differences in their knowledge base, procedural dexterity, and bedside manner, what else differentiates “good” from “bad” gastroenterologists? Two failures in particular seem to frequently characterize ineffective management skills. The first failure relates to the inability to establish a management goal that addresses the underlying medical problem. The primary problem may be only partly recognized or may be missed altogether and instead the goal of medical management becomes focused on a secondary problem or an unimportant side issue. As each diagnosis presents itself with multiple clinical symptoms, laboratory findings, and test results, a gastroenterologist may choose to manage a secondary symptom rather than the primary problem or underlying disease. Similarly, the correction of an abnormal laboratory test value or the pursuit of an intermediate outcome parameter could easily become the false foci of medical attention. The second failure relates to the inappropriate selection of test and procedural options to achieve the chosen management goal. A selected test procedure could be wrong because it is unable to yield any answers relevant to the management goal. Besides being blatantly wrong, a test could also be less effective because of its low sensitivity or specificity compared with other available tests. Medical pursuits may, thus, become inefficient for reasons associated with the first or second type of failure or even with both types combined, when a physician is simultaneously unable to focus on the right goal and also unable to assess the sequence of chosen interventions with regard to their goal relevance. Obviously, these types of failures apply to the management of any digestive disease. Because GI bleeding is a frequent issue of consults to gastroenterologists and because a large portion of GI endoscopy centers on diagnosis and treatment of GI bleeding, issues of focus and relevance frequently manifest themselves in the management of GI bleeding. Several examples are discussed in the following section to illustrate this point.
UNFOCUSED GOALS AND IRRELEVANT TESTS There are multiple examples of goals that are unfocused with respect to the primary medical problem. For instance, it is generally not recommended to excise www.giejournal.org
polyps during a colonoscopy performed for the workup of hematochezia. Unless they reach substantial size, the polyps are unrelated to the bleeding.1 The potential occurrence of postpolypectomy bleeding could further obfuscate the search for the primary bleeding site. It would be more appropriate to resolve the issue of hematochezia first and defer the polypectomy to a second colonoscopy at a later point in time. With respect to the primary problem of finding and treating the source of hematochezia, excising incidental polyps is a distraction. Similarly, in a patient with major GI bleeding, it would not be advisable to start GI endoscopy before cardiovascular resuscitation and stable hemodynamics have been achieved.2 The patient’s well-being and survival represent the primary medical problem. Finding and treating the bleeding lesion are ultimately only secondary goals in support of the primary goal. As a third example, consider a patient who presents with chronic watery diarrhea. Although on inspection the bowel movement appears watery brown, 1 of 3 fecal occult blood tests returns positive results. Frequent diarrhea can irritate the anal verge and cause minor bleeding from anal fissures or hemorrhoids.3 Obviously, the diagnostic workup should focus on finding and eliminating the cause of diarrhea rather than embarking on an endoscopic search for a potential GI bleeding site. Similarly, examples abound for irrelevant tests and endoscopic procedures with respect to managing GI bleeding. A test could simply represent a wrong choice for advancing the goal of diagnosing and treating the bleeding site. For instance, one would not start the workup for GI bleeding with a chest radiograph or magnetic resonance imaging of the head. In the same vein, a colonoscopy would not be the primary test to select for workup of hematemesis, nor would an EGD be the first procedure of choice for the workup of hematochezia. Besides the blatantly irrelevant tests, there are also procedural choices that do not miss their mark altogether, but still represent less-relevant options in pursuing the goal of finding and treating the bleeding lesion. In a patient with portal hypertension and maroon-colored stool, colonoscopy would represent only a secondary choice if the initial EGD failed to reveal a bleeding site. Similarly, after repeat EGDs and colonoscopies failed to reveal a bleeding site, yet another EGD would be considered a lesser option compared with CT angiography or capsule endoscopy. Volume 75, No. 4 : 2012 GASTROINTESTINAL ENDOSCOPY 861
Thinking outside the box
Sonnenberg
TABLE 1. 2 ⴛ 2 Matrices of the 3 relationships among test outcome, management goal, and underlying medical problem
Test-goal matrix (1)
EGD
Hematochezia Pos
Neg
Pos
20%
20%
Neg
80%
80%
(4)
Polypectomy
Colon polyps Pos
Neg
Pos
90%
5%
Neg
10%
95%
(7)
EGD
FOBT Pos
Neg
Pos
60%
40%
Neg
40%
60%
(10)
EGD
Goal-problem matrix
BII anemia
(2)
Hematochezia
UC flare Pos
Neg
Pos
60%
20%
Neg
40%
80%
(5)
Polyps
Hematochezia Pos
Neg
Pos
25%
25%
Neg
75%
75%
(8)
FOBT
(11)
Test-problem matrix
Diarrhea Pos
Neg
Pos
60%
30%
Neg
40%
70%
BII malnutrition
Pos
Neg
Pos
Neg
Pos
70%
30%
BII
Pos
70%
30%
Neg
30%
70%
Anemia
Neg
30%
70%
(3)
EGD
Neg
Pos
20%
20%
Neg
80%
80%
(12)
EGD
TP matrix, PPV
50%
50%
50%
50%
95%
50%
50%
60%
53%
50%
70%
58%
Hematochezia Pos
Neg
Pos
26%
26%
Neg
74%
74%
(9)
EGD
TG matrix, PPV
UC flare Pos
(6)
Polypectomy
Prior P
Diarrhea Pos
Neg
Pos
52%
46%
Neg
48%
54%
BII malnutrition Pos
Neg
Pos
58%
42%
Neg
42%
58%
Positive predictive value calculated using Bayes’ formula, for instance, in the case of matrix (9): 50% · 52%/(50% · 52% ⫹ (1 – 50%) · 46%) ⫽ 53%. UC, Ulcerative colitis; P, pretest probability; PPV, positive predictive value; Pos, positive; Neg, negative; FOBT, fecal occult blood test; BII, Billroth II partial gastrectomy.
FOCUS AND RELEVANCE IN TERMS OF SENSITIVITY AND SPECIFICITY The relationship between a test and the diagnosis or management goal can be phrased in terms of the conventional 2 ⫻ 2 matrix of true positive (sensitive), false positive, false negative, and true negative (specific) test results.4 The first example in Table 1 depicts the matrix of EGD in hematochezia. Endoscopy would be expected to yield a similar percentage of positive findings in subjects with or without hematochezia. Such a test would not raise the probability of having found the cause of hematochezia. This is indicated by the first positive predictive value in the second right-most column of the table, which is identical to the assumed prior probability of P ⫽ 50%. By contradistinction, colonoscopy with polypectomy is a highly sensitive and specific test for the diagnosis of polyps, as indicated by the fourth matrix of the table, capable of increasing the pretest (prior) probability from 50% to 95%. Similar to the test-goal matrix, one can phrase the relationship between management goal and actual problem in terms of a 2 ⫻ 2 matrix of sensitivity and specificity. The 862 GASTROINTESTINAL ENDOSCOPY Volume 75, No. 4 : 2012
fifth matrix of Table 1 describes the relationship between presence of colon polyps and hematochezia. Polyps would be found equally commonly among patients with or without hematochezia, indicating polypectomy to be a management goal that is unfocused with respect to the underlying medical problem of hematochezia. The 11th matrix depicts the relationship between anemia and general malnutrition in Billroth II partial gastrectomy. Anemia is depicted as a moderately sensitive and specific sign of malnutrition. The third set of matrices on the right side of Table 1 represents the test-problem matrices, depicting the relationships between test outcome and the actual medical problem. They are the product of multiplying the left with the middle set of matrices, that is, TP ⫽ TG ⫻ GP. (Such multiplication can be easily executed, for instance, on an Excel spreadsheet using its built-in MMULT function.5) The first row of matrices in Table 1 combines an irrelevant test with a moderately focused goal. The second row of matrices combines an excellent test with an unfocused goal. In both instances, the resulting test-problem matrix is characterized by 2 identical columns. As indicated by the corresponding positive predictive values in the far right www.giejournal.org
Sonnenberg
column, these 2 matrices would not be able to increase any pretest probability. In other words, any combination of an irrelevant test or an unfocused goal leaves the underlying medical problem unchanged because no headway can be made in affirming its presence. The third and fourth rows of matrices in Table 1 depict 2 examples in which moderately relevant tests were combined with moderately focused goals. The resulting test-problem matrices are far less efficient in increasing the pretest probability than any of its contributing matrices individually, highlighting the importance of combining a relevant test with a focused goal in pursuing a medical management problem.
CONCLUSION AND OUTLOOK For efficient resolution of GI bleeding, a gastroenterologist would need to stay focused on the underlying medical problem and choose the right sequence of test procedures relevant to achieving the treatment goal. Simple as these procedures may sound, physicians frequently fail to meet these 2 conditions. Preeminent among the reasons why medical pursuits fail are, first, a choice of wrong goals with respect to the underlying medical problem and, second, a choice of wrong tests with respect to the stated management goals. Focus on a wrong goal can potentially make the physician miss the underlying medical problem altogether and let it go unresolved. Choice of wrong test procedures delays reaching the aspired goals and, thus, renders the management process more dangerous and costly. Both types of error can contribute individually or jointly to poor management. As shown here, their joint contribution affects the overall outcome in a fashion that exceeds the negative influence of each error individually. To some extent, such errors can be avoided through training and experience. The workup of GI bleeding, how-
www.giejournal.org
Thinking outside the box
ever, is frequently initiated outside of gastroenterology through consult requests by critical or primary care physicians with only a limited understanding of the natural history of GI bleeding or the test characteristics of endoscopic procedures. Moreover, medical problems in general, and GI bleeding in particular, come in many disguises, which frequently defy the conditioned application of learned management patterns. Although this variety and novelty constitute the very appeal of clinical medicine, they also open the opportunity for endless failures and force the physician to focus on the right goals and relevant tests in each patient anew. DISCLOSURE The author disclosed no financial relationships relevant to this publication. REFERENCES 1. Zuckerman GR, Prakash C. Acute lower intestinal bleeding. Part II: etiology, therapy, and outcomes. Gastrointest Endosc 1999;49:228-38. 2. Yen D, Hu SC, Chen LS, et al. Arterial oxygen desaturation during emergent nonsedated upper gastrointestinal endoscopy in the emergency department. Am J Emerg Med 1997;15:644-7. 3. Friedman A, Chan A, Chin LC, et al. Use and abuse of faecal occult blood tests in an acute hospital inpatient setting. Intern Med J 2010;40:107-11. 4. Weinstein MC, Fineberg HV, Elstein AS, et al, eds. Clinical decision analysis. Philadelphia (Pa): WB Saunders; 1980. p. 75-130. 5. Bourg DM. Excel scientific and engineering cookbook. Sebastopol (Calif): O’Reilley Media; 2006. p. 225-6.
Portland VA Medical Center, Division of Gastroenterology/Hepatology, Oregon Health & Science University, Portland, Oregon, USA. Copyright © 2012 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 doi:10.1016/j.gie.2011.12.006
Volume 75, No. 4 : 2012 GASTROINTESTINAL ENDOSCOPY 863