Cost-Saving Approach to Patients on Long-Term Anticoagulation Who Need Endoscopy: A Decision Analysis

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1 THE AMERICAN JOURNAL OF GASTROENTEROLOGY Vol. 98, No. 8, by Am. Coll. of Gastroenterology ISSN /03/$30.00 Published by Elsevier Inc. doi: /s (03) Cost-Saving Approach to Patients on Long-Term Anticoagulation Who Need Endoscopy: A Decision Analysis Abraham Mathew, M.D., Thomas R. Riley, III, M.D., Mark Young, M.D., and Ann Ouyang, M.D. Departments of Medicine and Health Evaluation Sciences, Milton S. Hershey Medical Center, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania OBJECTIVE: The management strategies used when patients requiring long-term anticoagulation need endoscopic procedures vary considerably. Two commonly used approaches are a heparin window strategy in the inpatient setting and, more recently, a switch to low molecular weight heparin (LMWH) strategy for elective procedures. The aim of this study was to determine whether an initial diagnostic endoscopy (visualization only) is a cost-effective strategy in these patients. METHODS: Decision analysis was performed for two scenarios using probability estimates from our retrospective study. Scenario 1: Patients with any (urgent and elective) indication for endoscopy while on anticoagulation. A decision tree was made outlining two strategies: 1) a diagnostic endoscopy on full anticoagulation followed by therapeutic endoscopy if needed using standard practice; and 2) standard approach. Scenario 2: Patients requiring elective endoscopy. Here, the decision tree outlined three strategies: 1) initial diagnostic endoscopy on full anticoagulation followed by a therapeutic endoscopy if needed using a heparin window ; 2) initial diagnostic endoscopy followed by therapeutic endoscopy if needed using switch to LMWH strategy; and 3) direct switch to LMWH strategy. RESULTS: Initial diagnostic endoscopy is the preferred strategy when patients requiring anticoagulation need endoscopy. In scenario 1 (all patients), the diagnostic endoscopy approach will reduce need for hospital stay and save $85,006 per 100 patients when a therapeutic impact is not predictable before endoscopy. Similarly, in scenario 2, an initial diagnostic endoscopy followed by switch to LMWH strategy is the most cost saving. CONCLUSIONS: In anticoagulated patients, an initial diagnostic endoscopy approach on anticoagulation is the most cost-saving strategy, when a direct therapeutic impact is not predictable. (Am J Gastroenterol 2003;98: by Am. Coll. of Gastroenterology) Two abstracts were presented at the Annual Meetings of the American Gastroenterology Association, DDW 2000, May 21, 2000 and one abstract was presented at the American College of Gastroenterology Annual Meeting October 14, INTRODUCTION The number of people needing endoscopy while on anticoagulation is increasing because of the expanding indications for long-term anticoagulation. Patients with prosthetic valves, recurrent deep venous thrombosis, hypercoagulable diseases, and some vascular diseases are currently maintained on long-term anticoagulation. The need for anticoagulation makes decision making complex in these patients around the time of endoscopy. Little is published in the current literature on management of anticoagulation in these patients in the periprocedure period. The strategies used for management of anticoagulation vary considerably between physicians (1) and reflect lack of consensus. The costs of the commonly employed strategies vary and have not been studied. Recently, Goldstein et al. published a cost modeling study suggesting that low molecular weight heparin (LMWH) may be an economical alternative for anticoagulation in the periprocedure period (2). Current Management Strategies The current management strategies vary depending on the clinical situation and the clinician. The decision making is straightforward in patients who are unstable or have significant ongoing bleeding. Reversal of anticoagulation before emergent endoscopic evaluation is accomplished using fresh frozen plasma and vitamin K. Anticoagulation may be reinstated later after endoscopic therapy, depending on the endoscopic findings. Patients with less severe, but still significant bleeding, who are at high risk for thromboembolism, may be switched to shorter acting i.v. unfractionated heparin and admitted for close monitoring. The warfarin effect can be either reversed or prothrombin time (PT) allowed to drift back to normal depending on the urgency of the clinical situation. Endoscopic evaluation is then usually done using a heparin window where heparin is held for 4 6 h before a procedure. Then, i.v. heparin therapy is restarted within hours when endoscopic findings suggest that the risk of continuing or recurrent bleeding is low. The timing of reanticoagulation is subjective and depends on the findings at endoscopy and the therapeutic maneuvers done. Finding

2 AJG August, 2003 Cost Savings for Patients on Anticoagulation Needing Endoscopy 1767 a lesion with a high risk of bleeding may change the risk benefit ratio, and discontinuation of anticoagulant therapy may be needed. A similar strategy of hospital admission, i.v. heparin therapy, and endoscopy using a heparin window is followed when endoscopy is indicated for reasons other than bleeding, including elective endoscopy, in patients who require anticoagulation for indications where there is a high risk of thromboembolism (3). Heparin therapy is reinstated after the procedure and discontinued when a therapeutic anticoagulation status is achieved with oral warfarin therapy. Patients with low risk for embolism with isolated aortic valve replacement (AVR), atrial fibrillation, and remote history of deep venous thrombosis may be safely taken off anticoagulation for a short period for performance of endoscopic procedures. The current strategy using a heparin window is costly because of the need for a hospital stay and monitoring. The elevated PT (or international normalized ratio) from warfarin therapy drifts down to a safe range over 4 days in most people (4). The achievement of a therapeutic PT (or international normalized ratio) also needs around 4 days (5), resulting in several hospital days waiting a targeted coagulation status. Recently, physicians have been using a switch to LMWH strategy before procedure to avoid hospitalization for patients needing elective endoscopic procedures. This strategy consists of holding warfarin for a few days (the number of days varies with physicians), starting LMWH, then holding one or two doses of LMWH before the procedure, restarting warfarin after the endoscopic procedure, and maintaining LMWH till therapeutic PT is achieved. The cost-effectiveness of LMWH in this situation has not been established. We recently performed a retrospective study and found that most of the endoscopies performed urgently in the setting of continuing anticoagulation are of diagnostic rather than therapeutic nature (6). Given this situation, we hypothesized that an initial diagnostic endoscopy (visualization only) may be an effective strategy in patients requiring long-term anticoagulation. If a diagnostic endoscopy is performed, reversal of anticoagulation is not needed, as this will be a low-risk procedure (3). However, a repeat procedure and reversal of anticoagulation will then be needed in those requiring a therapeutic intervention based on the findings at the diagnostic endoscopy. Objectives of the Present Study The aim of this study is to compare the costs of an initial diagnostic endoscopic strategy with the commonly used strategies for management of patients needing endoscopy while on anticoagulation, using a decision analysis technique, and to define the most cost-saving strategy. MATERIALS AND METHODS Scenario 1 Here, the base case scenario is that of a patient requiring endoscopy on anticoagulation who is admitted to the hospital. This scenario is best represented the cohort of our retrospective study from which we obtained the probabilistic estimates (6). The decision tree included two strategies: 1) an initial diagnostic endoscopy approach, i.e., a diagnostic-only endoscopy (on full anticoagulation) followed by therapeutic endoscopy, if needed, using standard practice; and 2) standard heparin window approach (stop warfarin, start i.v. heparin in hospital, do endoscopy using a heparin window, restart warfarin, discharge patient). Scenario 2 This scenario is designed for the subgroup requiring an elective procedure. Here, the base case scenario is that of a patient who is anticoagulated for an indication with high risk of thromboembolism and therefore requiring elective endoscopy while maintained on anticoagulation. The probabilistic estimates were derived from the subgroup who underwent elective procedures among the patients included in our retrospective study (6). The decision tree included three strategies: 1) initial diagnostic endoscopy on full anticoagulation followed by a therapeutic endoscopy if needed using a heparin window ; 2) initial diagnostic endoscopy followed by therapeutic endoscopy if needed using switch to LMWH strategy (as explained below); and 3) switch to LMWH strategy (give LMWH while holding warfarin for 5 days, hold PM dose of LMWH before the day of procedure, do endoscopy prepared for potential therapeutic intervention, and keep LMWH for next 5 days while targeted PT is attained). Decision analysis was performed using decision trees constructed outlining different strategies that could be employed in managing patients in two scenarios as shown in Figure 1 and 2. General Assumptions The cost of an endoscopy is assumed to be the same in all the arms of both scenarios. A repeat procedure is more costly because of its therapeutic nature but is less likely to affect the cost equation, as it affects all strategies similarly. The model provides for only one procedure per patient, but the cost of the procedure used is a weighted average, considering multiple procedures in a patient. This calculation uses data regarding the number and kind of procedures done as presented in our retrospective descriptive study (6). Cost Analysis A standard spreadsheet in Microsoft Excel (Microsoft Corporation) format was used for data entry, calculation, and to generate the graphics. No formal decision software was used. The cost of endoscopy was estimated from the hospital (including procedure medications and room fees) and phy-

3 1768 Mathew et al. AJG Vol. 98, No. 8, 2003 Figure 1. Decision tree for Scenario 1. All patients requiring endoscopy on anticoagulation. sician charges. The estimated charge for colonoscopy, enteroscopy, and upper endoscopy was $1670, $1701, and $1545, respectively. The average hospital charges for a medical/surgical bed per day was $760, and this included all nursing, technical, and i.v. administration costs. The actual costs are estimated as 70% of the charges. The Probability Estimates Used From the Retrospective Study (6) In the overall cohort of 64 patients included in the retrospective study, 211 additional days were spent waiting a targeted international normalized ratio (average 3.3). Endoscopy had a direct therapeutic impact in 51%. In 16 of the 64 patients, a therapeutic impact was predictable because of known findings or planned interventions, and this accounted for 30 additional days. Excluding these patients, the average number of additional days used for those patients without a foreseen direct therapeutic impact will be 3.77 days [(211 30)/(64 16) 181/ ] (Table 1). A direct therapeutic impact was made in 35% of patients, excluding those with a predictable direct impact (Table 2). Patients who were admitted primarily for the performance of an endoscopy planned electively required an average of 4.88 days solely to achieve a targeted therapeutic coagulation status. This group included patients admitted for elective endoscopy and a few who were transferred from other hospitals for enteroscopy. The frequency of direct therapeutic impact was 18% in this subgroup. DECISION ANALYSIS Scenario 1: All Patients Requiring Endoscopy on Anticoagulation DECISION TREE. As explained before, a decision tree was made (Fig. 1) outlining two strategies: 1) the standard heparin window approach; and 2) a diagnostic endoscopy (on full anticoagulation) followed by therapeutic endoscopy if needed using the standard approach. The fraction of patients needing a repeat endoscopy includes those in whom a direct therapeutic impact is expected and is estimated as 35% (as discussed earlier, Table 2). Calculation of Cost Differences The cost of the initial endoscopy can be assumed to be equal in both arms. Cost of heparin was not considered as it affected the total cost only negligibly in scenario 1. The cost difference between the two approaches or savings from proposed initial diagnostic endoscopy (visualization only)

4 AJG August, 2003 Cost Savings for Patients on Anticoagulation Needing Endoscopy 1769 Figure 2. Decision tree for Scenario 2. Patients requiring elective endoscopy while on anticoagulation. approach was calculated using probability estimates, as discussed before, and is shown in Appendix 1. In summary, the cost of standard heparin window approach was $330,164 per 100 patients, whereas the cost of initial endoscopy approach was $245,157. This resulted in a net savings of $85,006 per 100 patients. Using charges, the savings will be $121,418 per 100 patients. Threshold Analysis The threshold analyses (Table 3) showed that diagnostic endoscopy on anticoagulation was preferable as long as the expected chances of therapeutic intervention were less than 61%. This threshold could be calculated by a simple formula, H/H P, where H cost of hospital stay for the given number of additional days, and P cost of procedure. Multiway sensitivity analyses showing the thresholds for various costs for endoscopy, fraction of repeat procedures, and additional hospital days used are shown in Table 3. Sensitivity Analysis Sensitivity analyses were done for significant variables (Fig. 3 and 4). The changes in cost of the procedure had a smaller effect on the cost difference, whereas the changes in hospital costs affected it significantly. A substantial cost difference was maintained for a wide range of costs for endoscopy, hospital stay, and fraction needing a repeat procedure. In our analysis, 70% of charges was used as an estimate of cost. The savings if this fraction were different could be calculated by multiplying $121,418 by the assumed fraction reflecting the cost. For example, if the cost is estimated to be 50%, the savings will be $60,709. Table 1. Additional Days Used in Different Subgroups Number of Patients Additional Days Average Number of Additional Days Admission for Scheduled endoscopy (EGD/colon enteroscopy) (11 6) (60 23) ( ) GI bleeding Other GI diagnosis Non-GI diagnosis Total Total excluding those with a predictable therapeutic impact EGD esophagogastroduodenoscopy

5 1770 Mathew et al. AJG Vol. 98, No. 8, 2003 Table 2. Frequency of Direct Therapeutic Impact in Different Subgroups Indication for Endoscopy Number of Patients Impact Made Percentage Significant bleeding 21 12/21 57 Other* 27 5/27 18 Total 48 17/48 35 * Includes nonsignificant bleeding, abdominal pain, anemia, diarrhea, etc. Analysis excludes 16 patients with predictable impact (100%) even before endoscopy seven who had ERCP, four with known findings needing intervention of radiological studies, one PEG placement, and four cases done with intention of biopsy. Table 3. Scenario 1: All Patients Requiring Endoscopy on Anticoagulation Multiway Threshold Analysis of Fraction of Repeat Procedures Above Which There Are No Savings Assumed Cost for a Procedure Threshold Fractions Assuming the Additional Time to Be 2.5 days 3.77 days 5 days $ $ $ Scenario 2: Patients Requiring Elective Endoscopy While on Anticoagulation DECISION TREE. Many patients who need elective endoscopy can be taken off anticoagulation safely if the underlying indication for anticoagulation is low risk, as explained before. For those patients requiring elective endoscopy who need to be maintained on anticoagulation because of high risk of thromboembolism, a decision tree outlining three strategies (Fig. 2) was made as follows: 1) initial diagnostic endoscopy on full anticoagulation followed by a therapeutic endoscopy if needed using a heparin window (stop warfarin, start i.v. heparin in hospital, do endoscopy using a heparin window, restart warfarin, discharge patient); 2) initial diagnostic endoscopy followed by therapeutic endoscopy if needed using switch to LMWH strategy (as explained in the Materials and Methods section); and 3) switch to LMWH strategy (as explained in the Materials and Methods section). Calculation of Cost Differences The cost of initial endoscopy is again assumed to be equal in both arms. Cost of outpatient care and possible complications were not factored in the analysis. It was assumed that when the switch to LMWH strategy is used, PT will have to be checked three times to assess coagulation status (one before and two after the procedure). Similarly, if the unfractionated heparin strategy is used, PT and PTT are assumed to be checked on every hospital day. The daily dose of heparin was assumed to be 25,000 U. Enoxaparin was used as prototype of LMWH for cost calculations. The details of the calculations are shown in Appendix 2 and are summarized here: The cost from traditional heparin window approach without switching to LMWH or a diagnostic procedure was $389,216 ($556,080) per 100 patients. For a direct switch to LMWH strategy, the cost would be $176,780 ($252,600). If an initial diagnostic endoscopy strategy is used followed by LMWH or heparin strategy, the costs would be $161,420 ($230,668) or $202,730 ($289,682), respectively. Threshold Analysis First, we analyzed diagnostic endoscopy followed by switch to LMWH versus direct switch to LMWH. Threshold analyses (Table 4 and 5) were done for the two Figure 3. Scenario 1. All patients requiring endoscopy on anticoagulation. Sensitivity analyses savings for varying costs hospital day and cost of endoscopy.

6 AJG August, 2003 Cost Savings for Patients on Anticoagulation Needing Endoscopy 1771 Figure 4. Scenario 1. All patients requiring endoscopy on anticoagulation. Sensitivity analyses savings with different hospital costs and varying fraction of repeat procedures. significant variables in Scenario 2, frequency of needing a repeat procedure, and cost of LMWH. Initial diagnostic endoscopy on anticoagulation followed by switch to LMWH strategy was cost saving as long as the expected chances of therapeutic intervention were less than 26%, assuming the costs as listed before. If LMWH costs less than $25 per day, the advantage of initial diagnostic approach will be offset given other estimates remain the same. Thresholds for a given cost of LMWH or fraction needing repeat procedure and sensitivity analysis of the threshold are shown in Table 5. As the cost of procedure decreases, the threshold fraction increases and threshold cost of LMWH decreases for given values of each other. In other words, the threshold fraction is directly and threshold cost is indirectly proportional to the cost of the procedure. Second, we analyzed diagnostic endoscopy followed by switch to LMWH versus heparin window. Diagnostic endoscopy followed by the switch to LMWH approach is preferred compared with the standard approach. As the costs of the hospital day and cost of procedure gets lower, the net savings decrease and are shown in the sensitivity analysis (Fig. 5). The thresholds corresponding to the cost of a day and procedure are also shown in the figure. Finally, we analyzed direct switch to LMWH versus diagnostic endoscopy followed by heparin window. A direct switch to LMWH approach is cost saving compared with diagnostic endoscopy followed by the heparin window approach as long as the frequency of repeat procedures was greater than 10%. Sensitivity Analysis Frequency of needing repeat endoscopy, cost of procedure, the cost of a hospital day, and cost of LMWH were subjected to two-way sensitivity analyses (Fig. 6, 7, and 8). The initial diagnostic endoscopy followed by the switch to LMWH heparin strategy remained cost saving for a wide range of procedures, and LMWH costs compared with the other strategies as shown in the sensitivity analysis. Diagnostic endoscopy followed by the heparin window approach was more costly compared with a switch to LMWH approach. Cost savings from the switch to LMWH approach increases with the increasing cost of day and the frequency of repeat procedures. When the heparin window Table 4. Scenario 2: Patients Requiring Elective Endoscopy While on Anticoagulation Threshold Analysis of Cost of LMWH That Offsets Savings From Diagnostic Endoscopy Repeat With Switch to LMWH Versus Direct Switch to LMWH Assumed Cost for a Procedure Threshold Cost of LMWH Assuming the Fraction Needing Repeat Procedure to Be $ $ $ Table 5. Scenario 2: Patients Requiring Elective Endoscopy While on Anticoagulation Threshold Analysis of Cost of LMWH That Offsets Savings From Diagnostic Endoscopy Repeat With Switch to LMWH Versus Direct Switch to LMWH Assumed Cost for a Procedure Threshold Fractions Assuming the Cost of LMWH to Be $ $ $

7 1772 Mathew et al. AJG Vol. 98, No. 8, 2003 Figure 5. Scenario 2. Patients requiring elective endoscopy while on anticoagulation (sensitivity analysis). Diagnostic endoscopy plus switch to i.v. heparin versus diagnostic endoscopy plus switch to LMWH strategies. strategy is involved, the total cost is very sensitive and increases with the cost of the hospital stay. DISCUSSION The GI tract is a common site of bleeding in patients on anticoagulation. In up to a third of patients, previously unknown lesions could be found on diagnostic evaluation (7). The management of anticoagulation around the time of endoscopy is important and complex. When the risks of anticoagulation outweigh the benefits, decision making is more straightforward, and cessation and rapid reversal of anticoagulation is needed. The heparin window approach is recommended if a patient needs to be on anticoagulation for an underlying condition with high thromboembolic risk (pulmonary embolism or deep venous thrombosis within the previous month, prosthetic valves at two locations, prosthetic valve with atrial fibrillation, mitral valve prosthesis, or history of recent arterial thromboembolism). If reversal of oral anticoagulant therapy is needed in a high-risk scenario, use of LMWH after stopping warfarin therapy in the outpatient setting before endoscopy may be an effective approach. Though this is adequate therapy for patients with deep venous thrombosis or pulmonary embolism, it has not been established to be effective in people with prosthetic valves except in pregnancy (8, 9). We used actual probabilistic estimates from our retrospective data for the calculations. It differs from Goldstein et al. s cost modeling study (2) in using a weighted average for procedure costs and analyzing urgent and elective scenarios where patients on anticoagulation need endoscopy. We did not include the risk of thromboembolism from cessation on anticoagulation, as the risk is small and not accurately known. It is very difficult to quantify the risk of stopping anticoagulation for a few days in all the scenarios from the available literature. This is because the risk is quantified as event per patient years and not as event per day. In the above-mentioned study, the cost of a thromboembolic event was estimated to be $10, and the expected incidence was 0.4%. This is only a minor economic determinant, as the cost is in the order of hundred thousands for the care of 100 patients. The occurrence of a thromboembolic event, on the other hand, will introduce other concerns including legal and quality-of-life issues on which scientific data are not available. When reversal of anticoagulation is needed, it is performed using a variety of methods including fresh frozen plasma, vitamin K, or just holding warfarin. There are no published data on the most cost-effective strategy to reverse anticoagulation. Administration of low-dose vitamin K may be a cost-effective strategy, but no specific dosing regimen is available. We did not consider these strategies in this cost analysis study. Barium studies were not included in the decision tree because of their known decreased sensitivity, especially for lesions such as arteriovenous malformation, which was a

8 AJG August, 2003 Cost Savings for Patients on Anticoagulation Needing Endoscopy 1773 Figure 6. Scenario 2. Patients requiring elective endoscopy while on anticoagulation (sensitivity analysis). Direct switch to LMWH versus diagnostic endoscopy plus switch to LMWH. Varying procedure costs and costs from LMWH. Figure 7. Scenario 2. Patients requiring elective endoscopy while on anticoagulation (comparison of strategies and sensitivity analysis).

9 1774 Mathew et al. AJG Vol. 98, No. 8, 2003 Figure 8. Scenario 2. Patients requiring elective endoscopy while on anticoagulation. Diagnostic endoscopy plus repeat with heparin window versus direct switch to LMWH (sensitivity analysis). Savings for varying hospital day cost and frequency of repeat procedure. frequent finding in the study group. Double-contrast barium enema has been known to be less accurate than colonoscopy in detecting polyps. Cost Savings Considering All Endoscopies (Urgent and Elective) Significant cost savings resulted from the initial diagnostic endoscopic approach by reducing the number of hospital days in scenario 1. This was close to $100,000 per 100 patients when a direct therapeutic impact could not be predicted. The number of additional days spent awaiting a targeted anticoagulation status in the overall cohort was very conservatively calculated as 3.77 per patient and is likely an underestimate. The patients who had an initial stay at other hospitals before transfer have likely used more additional days, which were not accounted because of unavailability of details of daily plans during the stay. Inclusion of these days likely would have increased the additional number of days and the calculated cost savings. The patients with a non-gi diagnosis used up fewer additional days. This may just be a reflection of the strict definition of an additional day. The anticipated longer stay as a result of the routine need for adjusting coagulation status may have caused other medical issues to be addressed less aggressively, distributing it over the additional days. A choice of earlier endoscopic evaluation likely would have shortened the stay more than suggested by the additional days used. As the hospital costs (number of additional days or cost of day) increase, an initial diagnostic endoscopic approach is favored. All patients who had ERCP had therapeutic maneuvers done making a 100% chance of direct therapeutic impact. Thus, there was no role for an initial diagnostic examination. Purely diagnostic ERCP testing is becoming rare with use of noninvasive imaging, such as magnetic resonance cholangiopancreatography. For a diagnostic ERCP, the chance of direct impact may be lower and could be below the threshold. Cost Savings Considering Elective Endoscopy The most cost-saving strategy when elective endoscopy is needed in those on anticoagulation is an initial diagnostic endoscopy followed by a switch to LMWH strategy. This approach will save around $15,000 per 100 patients compared with a direct switch to LMWH strategy. Routine switching of all patients to LMWH before procedure costs less compared with the standard heparin window and diagnostic heparin approach. If a repeat procedure is needed, a switch to LMWH strategy is preferred over the more commonly used heparin window approach, provided LMWH is adequate therapy for the underlying condition necessitating anticoagulation. The net saving is most sensitive to the cost of LMWH and is directly proportional to it. Compared with the traditional approach, the initial diagnostic endoscopy followed by a switch to LMWH strategy saves more than $200,000 per 100 patients. Limitations of the Study In this study, we used 70% of charges as the estimate of true costs. The actual cost of endoscopic procedures and hospital

10 AJG August, 2003 Cost Savings for Patients on Anticoagulation Needing Endoscopy 1775 days is difficult to estimate. Charges billed vary considerably across practices. An alternative was to use Medicare reimbursement for the analyses. However, the payments for a hospital admission are bundled together as one fee and are based on diagnosis-related group codes (not number of days), making it almost impossible to calculate the reimbursement for a hospital day. Reimbursements for procedures also vary but are around $538 for esophagogastroduodenoscopy, $635 for colonoscopy, and $571 for enteroscopy. These include both the facility and professional components. It should be noted that the sensitivity analyses performed in this situation help to estimate savings based on any assumed cost of procedure or hospital day and to define thresholds beyond which there are no cost savings for a strategy. With formal decision software, more mathematically elegant analysis could have been done. However, our approach has the advantage of being simple, sensible, and clear to clinicians. We did not include the costs of fresh frozen plasma and vitamin K in the calculations, as no data were available on their use. The inclusion of these costs will likely increase the cost of standard approach, though minimally This study presents only the clinicians or providers point of view. In the proposed initial diagnostic endoscopic approaches, there are chances for needing a second procedure, and therefore patient preferences may vary. In addition, at present, the insurance coverage for a second procedure is uncertain. The standard approach necessitates a prolonged hospital stay, more blood draws, and manipulation of coagulation status in all patients. The initial diagnostic endoscopy approach will lead to significant cost savings and may reduce the risk of thromboembolism by making manipulations of coagulation status unnecessary. CONCLUSIONS In this era of cost management, careful scrutiny of clinical management strategies is needed. The commonly used strategy for managing patients who need endoscopy while on anticoagulation is expensive. The bulk of the cost is incurred from the hospital days that are used waiting for an appropriate coagulation status and may be avoided. Based on the retrospective review of our patient population, an initial diagnostic endoscopy approach will be cost saving. This approach can save close to $100,000 per 100 patients undergoing endoscopy while on anticoagulation. When elective endoscopy is indicated, a diagnostic endoscopy followed by a switch to LMWH strategy is preferred. We have defined the effect of cost and patient population variables on the cost incurred in the management of patients needing endoscopy while on anticoagulation. The findings of this decision analysis using our retrospective data need to be confirmed by prospective evaluation with emphasis on the safety of such approaches and patient preferences. Also, cost-effective strategies for reversal of anticoagulation when such is indicated need to be defined. Reprint requests and correspondence: Abraham Mathew, M.D., Assistant Professor of Medicine, Division of Gastroenterology and Hepatology, The Milton S. Hershey Medical Center, The Pennsylvania State University College of Medicine, MC HO45, 500 University Drive, Hershey, PA Received May 28, 2002; accepted Jan. 30, REFERENCES 1. Kadakia SC, Angueira CE, Ward JA, et al. Gastrointestinal endoscopy in patients taking antiplatelet agents and anticoagulants: Survey of ASGE members. Gastrointest Endosc 1996;44: Goldstein JL, Larson LR, Yamashita BD, et al. Low molecular weight heparin versus unfractionated heparin in the colonoscopy peri procedure period: A cost modeling study. Am J Gastroenterol 2001;96: Guideline on the management of anticoagulation and antiplatelet therapy for endoscopic procedures. Gastrointest Endosc 1998;48: White RH, McKittrick T, Hutchinson R, et al. Temporary discontinuation of warfarin therapy: Changes in international normalized ratio. Ann Intern Med 1995;155: Kearon C, Hirsh J. Management of anticoagulation before and after elective surgery. N Engl J Med 1997;336: Mathew A, Ouyang A, Riley TR, et al. Endoscopy in those requiring long term anticoagulation. Gastrointest Endosc 2000; 51: Sethlandefeld C, Beyth RJ. Anticoagulant-related bleeding: Clinical epidemiology, prediction and prevention. Am J Med 1993;95: Sirguasa S, Cosmi B, Piovella F, et al. Low-molecular weight heparins and unfractionated heparin in the treatment of patients with acute venous thromboembolism. Results of a meta-analysis. Am J Med 1996;100: Lashner BA, Silverstein MD. Coagulation and therapy of the patient with fecal occult blood loss: A decision analysis. Am J Gastroenterol 1990;85: APPENDIX 1 The probabilistic estimate of fraction needing repeat endoscopy is 35% (Table 2), and number of additional days per patient is 3.77 (Table 2). These are obtained from our retrospective data, as explained before. Cost (charge) estimates for a hospital day (includes technician charges and i.v. supplies) $532 ($760/day), and cost of a procedure $1296 ($1852). The cost information is obtained from the Hershey Medical Center statistics. The calculations are for 100 patients at the base case scenario. 1. Cost from traditional heparin window approach For 100 patients, the cost cost of initial procedure cost of additional days (100 $1296) ( $532) $330,164.

11 1776 Mathew et al. AJG Vol. 98, No. 8, Cost from the proposed initial diagnostic endoscopy approach Cost from the proposed initial diagnostic endoscopy approach cost of initial procedure repeat procedure hospital stay. The frequency of repeat procedure from of data is 35%. Therefore, The cost for 100 patients (100 $1296) [(35 $1296) ( $532)] $245, Calculation of cost savings The cost difference (savings) cost of standard approach cost of proposed approach $330,164 $245,157 $85,007 per 100 patients Using charges the savings $121,418 per 100 patients. APPENDIX 2 The probabilistic estimate of fraction needing repeat endoscopy is 18% (Table 2), and number of additional days per patient if unfractionated heparin is used is 4.88 (Table 1). These are obtained from our retrospective data, as explained before. Cost (charge) estimates used were hospital day $532 ($760/day), procedure $1296 ($1852), enoxaparin 80 mg b.i.d. $62 ($43.4), unfractionated heparin/ 25,000 U $3.95 ($2.77), PT $18 ($12.6), and PTT $28 ($19.6). The cost information is obtained from the Hershey Medical Center statistics. The calculations are for 100 patients at the base case scenario. 1. Cost from traditional heparin window approach The cost from the traditional heparin window approach without switching to LMWH or doing an initial diagnostic endoscopy was calculated as in scenario 1 using probability estimates relevant to elective procedure. This equals $389,216 ($556,080) per 100 patients (probability estimates, Scenario 2: additional days 4.88, fraction needing patient procedures 18%). 2. Cost from direct switch to LMWH approach Cost from a switch to LMWH approach without an initial diagnostic endoscopy cost of 10 days of LMWH cost of procedure cost of PT 3. For 100 patients, the cost (charge) ( $43.4) (100 $1296) (100 $12.6 3) $176,780 ($252,600). 3. Cost from initial diagnostic endoscopy followed by switch to LMWH approach Cost from an initial diagnostic endoscopy followed by switch to LMWH approach cost of initial procedure cost of repeat procedure using switch to LMWH strategy. Therefore, the cost (charge) for 100 patients (100 $1296) 18 (10 $43.4 $1296 $12.6 3) $161,420 ($230,668). 4. Cost from initial diagnostic endoscopy followed by heparin window approach Cost from an initial diagnostic endoscopy followed by heparin window approach cost of initial procedure cost of repeat procedure using heparin window approach. The cost of initial procedure (100 $1,296) $112,800. The cost of repeat procedure for 18 patients 18 (cost of 4.88 hospital days cost of 4.88 days of heparin cost of procedure cost of PTT 4.88 cost of PT 4.88). Total cost (charge) $129,600 (18 $[( ) ( ) 300 ( ) ( )] $202,730 ($289,682). 5. Cost savings for 100 patients Cost (charge) savings from diagnostic endoscopy with switch to LMWH versus standard approach $389,216 $161,420 $227,796 $325,412. Cost (charge) savings from diagnostic endoscopy with switch to LMWH versus direct switch to LMWH approach $176,780 $161,420 $15,360 $21,932. Cost (charge) savings from diagnostic endoscopy with switch to LMWH versus diagnostic endoscopy with switch to heparin $202,730 $161,420 $41,310 $59,016.