Coronary artery bypass grafting: How much does it cost?

Transcription

1 CLINICAL AND COMMUNITY STUDIES 0 ETUDES CLINIQUES ET COMMUNAUTAIRES Coronary artery bypass grafting: How much does it cost? Hans Krueger, MSc; Jose L. Goncalves; Frances M. Caruth, MSc; Robert I. Hayden, MD Objective: To calculate the cost of coronary artery bypass grafting (CABG) and to compare it with the costs determined in two previous Canadian studies. Design: Retrospective cost-analysis study. Setting: A tertiary care referral hospital. Patients: Fifty patients who had undergone successful triple and quadruple CABG between Jan. 3 and 30, Main results: The cost of CABG per patient varied from $ to $ (mean $14 328) (in 1988 Canadian dollars). The cost tended to increase with age and number of vessels grafted. Compared with the patients in the two previous Canadian studies our patients were older, had more vessels grafted and cost more to treat, even after the total hospital costs were adjusted for inflation. Conclusions: The population undergoing CABG is changing: it is older and has more diseased vessels. These changes have had a significant impact on the cost of CABG. Further study is required to determine the outcome and benefit of CABG in this group of patients. Objectif: Calculer le cofit d'un pontage de l'artere coronarienne (PAC) et le comparer aux cofits etablis par deux etudes canadiennes anterieures. Conception: Analyse de cofit retrospective. Contexte: H6pital de soins tertiaires. Patients: Cinquante patients qui ont subi avec succes un triple et quadruple PAC entre le 3 et le 30 janvier Resultats principaux: Le cout d'un pontage varie de $ a $ (moyenne, $) (en dollars canadiens de 1988). Le cofit a tendance a augmenter avec l'age et le nombre de vaisseaux greff6s. Comparativement aux patients des deux etudes canadiennes anterieures, nos patients etaient plus ages, ont subi une greffe de vaisseaux plus nombreux et ont coufte plus cher A traiter, meme une fois corrig6s de l'inflation tous les frais d'hospitalisation. Conclusions: La population qui subit un PAC change: elle est plus agee et les vaisseaux malades sont plus nombreux. Ces changements ont eu un effet important sur le cout des PAC. Une etude plus poussee s'impose si l'on veut etablir les resultats et les avantages du pontage chez ce groupe de patients. At the time the paper was written Mr. Krueger and Ms. Caruth were with the Clinical Resource Management Support Group, Vancouver General Hospital, Vancouver, BC, Mr. Goncalves was a second-year medical student at the University ofbritish Columbia, Vancouver, BC, and Dr. Hayden was in the Department ofcardiac Surgery, Vancouver General Hospital, Vancouver, BC. Reprint requests to: Mr. Hans Krueger, Director, Clinical Resource Management Support Group, Vancouver General Hospital, 855 W 12th Ave., Vancouver, BC V5Z IM9 - For prescribing information see page 284 CAN MED ASSOC J 1992; 146 (2) 163

2 T he current health care environment is one in which providers vie for resources and politicians, planners, administrators and health care workers have to make difficult allocation decisions. In such an environment it is essential that everyone be aware of how resources are used and what the costs of the available services are. One controversial resource-intensive procedure is coronary artery bypass grafting (CABG). To assist in public-policy-making in this area we report on the costs of CABG and assess the new data from the Vancouver General Hospital in comparison with the findings of two previous Canadian studies.",2 A number of international studies have directly or indirectly addressed the cost of open heart surgery.3-'0 The results are difficult to interpret, mainly because the studies tended to use patient charges as a proxy for costs. Charges are not an accurate estimation of the true cost of treatment."12 Finkler'2 concluded that true economic cost should be calculated by applying prices to patient-specific resource consumption. We have attempted to follow that procedure in determining the costs of CABG. The first published Canadian study of the cost of CABG was performed in 1983 at the Univcrsity of Ottawa Heart Institute. Keon, Menzies and Lay' randomly selected 50 patients and determined that the average cost was $9595 (in 1983 Canadian dollars); this included hospital inpatient costs and professional fees. More recently Laupacis and associates2 used a fully allocated costing method to determine the average cost per treatment. Because their costs were fully allocated across all hospital departments they reflected not only the direct costs of treatment but also an appropriate share of support and overhead costs. Using a retrospective consecutive sample of 50 patients who had undergone CABG the authors determined that the average cost was $ (in 1985 Canadian dollars). Of this amount, $ was for the inpatient stay and $3291 for professional fees. The goals of our study were (a) to determine an accurate cost for triple and quadruple CABG performed at the Vancouver General Hospital (patientspecific resource consumption being used as a base) and (b) to compare the results with previously published Canadian data. Methods Study population We selected 50 consecutive patients who had undergone successful triple and quadruple CABG uncomplicated by valve replacements or other procedures at the Vancouver General Hospital between Jan. 3 and 30, These types of bypass were chosen because they are the most frequently performed open-heart procedures at the hospital. (The Vancouver General Hospital, a tertiary care hospital with 800 acute care beds, performs about 900 open-heart operations per year; 65% are CABG without associated procedures, and of these 70% are three-vessel or four-vessel bypasses.) Patients requiring CABG undergo the following steps: admission for routine tests and blood work 1 day before surgery, extubation after surgery (usually the next morning) and monitoring for about 2 to 3 days in the cardiac surgery intensive care unit. After stabilization the patient is sent to the cardiovascular surgical ward for about 7 to 9 days. Cost analysis The fundamental process of estimating costs is the same across all industries. The cost of a product or service is an aggregate of labour, supply and infrastructure (overhead) costs. In this study, only the fully allocated hospital costs and the professional fees relating to CABG were used. Capital depreciation and costs borne by the patient were not included. Table 1 provides a summary of the resources included and the method of cost calculation. Patient-specific resource use in each department was determined either from a computer database or from the patient's medical record. If that information was unavailable average resource consumption was determined by the manager of the relevant department or by a clinician from the department on the basis of standard protocols. This average resource consumption was used to calculate the costs of respiratory therapy, rehabilitation services, clinical dietetics and social services. The resources consumed in these four areas account for 12.3% of the total hospital cost of treatment. Overhead was determined with the use of stepdown allocation. About 38% of the hospital's annual operating budget is considered to be overhead. This proportion fluctuates between areas, depending on such factors as the number of full-time-equivalent employees and the area of the building space. In the laboratory, for example, 25% of the total cost of operating the department is considered to be overhead, as compared with 48% on the general wards. More detailed information about costing at the Vancouver General Hospital can be obtained from the first author. Results Patient characteristics Table 2 compares the characteristics of the 164 CAN MED ASSOC J 1992; 146 (2) LE 1 5 JANVIER 1992

3 patient sample with those of the patients in the two previous Canadian studies."2 The length of stay for our patients varied from 8 to 43 (mean 12.1, median 11) days. In a special care unit it was from 1 to 6 (mean 3.1) days and on the general ward from 5 to 38 (mean 9.0) days. One patient was in hospital for 43 days but was 82 years of age and suffered from numerous complications. Because of the potential impact on the cost of performing CABG it is important to note at least two differences between our sample and those in the two other studies. First, the mean age of the patients JANUARY 15, 1992 in our study was higher (63.4 years v years' and 58 years2). Second, we included only patients who had three or four (mean 3.44) vessels grafted, as compared with one to three (mean 2.6) vessels in the Ottawa study' and two to six (mean 2.96) vessels in the London study.2 Hospital and physician costs Table 3 shows the distribution of the total cost of the procedure by department. The mean cost of the 50 patients is included, along with the cost CAN MED ASSOC J 1992; 146 (2) 165

4 of the least expensive and the most expensive patients in each department. The total inpatient cost was found to vary from $ to $ (mean $14 328). The operating room, the special wards and the general wards accounted for 73.7% of the total cost. The professional fees were $3357 per treatment on average; this represented 19% of the total cost per treatment. In the two previous Canadian studies the professional fees represented 23.5%' and 22%2 of the total cost per treatment. Table 4 examines the impact of age and the number of diseased vessels on hospital costs. As has been suggested by Keon, Menzies and Lay' costs tend to increase with age and number of vessels grafted..%..:.:;.:: ;:J>!-.-" CAN MED ASSOC J 1992; 146 (2) LE 1 5 JANVIER 1992

5 Discussion To determine whether our sample was representative and that the cost calculated for the sample could be projected onto CABG patients we compared our patients with the 1989 CABG population at the hospital (Table 5). No obvious differences were apparent. One must remember that the costs identified are institution-specific. Teaching hospitals have higher overhead costs because of their teaching and research functions and thus have higher unit costs of procedures performed. Because the Vancouver General Hospital is a teaching hospital one would expect to see a higher overhead portion in the total CABG cost than there might be in a nonteaching hospital. One of the purposes of this study was to compare data from previous Canadian studies. The study by Keon, Menzies and Lay' used 1983 Canadian dollars and the one by Laupacis and associates Canadian dollars. We used 1988 Canadian dollars, and thus our findings represent an update and allow one to begin to examine trends. All three studies involved 50 patients, with about the same sex distribution (Table 2). Our patients had a higher mean age and mean number of diseased vessels. As suggested earlier, these two factors affect hospital resource use. An analysis of statistics for 1986 from our hospital indicated that CABG patients had a mean age of 61 years, as compared with the 63.4 years in this study. There may be many reasons for these differences in age. For instance, the criteria for CABG may have changed, and the proportion of people in British Columbia (especially in Vancouver) over the age of 65 years is greater than the proportion in the rest of Canada.13 There were differences in admission categories between our study and the one by Keon, Menzies and Lay.' Either the criteria differed for the classification of categories or our sample was sicker. However, given that the age of our sample was higher than that of the CABG population at our hospital in 1986, the speculation that the population of patients receiving CABG is changing must be seriously entertained. Some recent evidence from Canada and the United States has suggested that the CABG population is indeed changing. Nuanheim and colleagues,14 in comparing the clinical profiles of patients undergoing CABG in 1975 and 1985 with respect to known preoperative risk factors and surgical outcome, found that the mean age had increased from 52.2 to 61.1 years and that significantly more patients had associated disease such as diabetes mellitus and chronic lung disease. The incidence rate of JANUARY 15, 1992 CAN MED ASSOC J 1992; 146 (2) 167

6 emergency operations and postoperative deaths also increased significantly during this time. Work done in Ontario"5 and British Columbia'6 confirms this finding. In their document prepared for the British Columbia Royal Commission on Health Care and Costs, Sheps and Gait'6 stated that between 1979 and 1988 the mean age of patients undergoing CABG in British Columbia increased from 57.0 to 62.5 years. The greatest increase in the rate of CABG was observed in the group of people aged 75 years or more (an eightfold increase). The number of patients with a concurrent disease (diabetes mellitus or chronic obstructive pulmonary disease) also increased dramatically, from 1.7% in 1979 to 16.5% in The apparent changes in the CABG patient population will increase the average cost of treating these patients and will at least explain in part why our costs were higher than those in the two previous Canadian studies, even after adjustments for inflation. The changing characteristics need to be considered when resource allocation decisions are made. An analysis of this type is just the first step in supporting resource allocation decisions. Further study is required to determine the outcome and benefit of CABG for this group of older and sicker patients. The findings will help in policy-making in this controversial resource-intensive area. We thank Dr. G. Frank 0. Tyers, professor and head of cardiovascular and thoracic surgery at the University of British Columbia, Vancouver, and head of cardiovascular surgery at the Vancouver General Hospital, for his helpful comments on an earlier draft. Mr. Goncalves was financially supported by the Medical Research Council of Canada. References 1. Keon WJ, Menzies SC, Lay CM: Cost of coronary artery bypass surgery: a pilot study. Can J Surg 1985; 28: Laupacis A, Labelle R, Goeree R et al: TIhe cost-effectiveness of routine post-myocardial infarction exercise stress testing. Can J Cardiol 1990; 6: Monro JL, Mollo S, Brookbanks S et al: The cost of cardiac surgery. BMJ 1978; 1: Nightingale CH, Robotti J, Deckers PJ et al: Quality care and cost-effectiveness: an organized approach to problem solving. Arch Surg 1987; 122: Tomatis LA, Schlosser RJ, Riahi M et al: Cost containment via expense rationalization in open-heart surgery. J Thorac Cardiovasc Surg 1979; 77: Loop FD, Christiansen EK, Lester JL et al: A strategy for cost containment in coronary surgery. JAMA 1983; 250: Konttinen M, Harjola PT, Heinonen M et al: Direct hospital costs in coronary bypass surgery. Ann Chir Gynaecol 1985; 74: Jang GC, Block PC, Cowley MJ et al: Relative cost of coronary angioplasty and bypass surgery in a one-vessel disease model. Am J Cardiol 1984; 53: 52C-55C 9. Reeder GS, Krishan I, Nobrega FT et al: Is percutaneous angioplasty less expensive than bypass surgery? N Engl J Med 1984; 311: Stoney WS, Alford WC, Burrus GR et al: The cost of coronary bypass procedures. JAMA 1978; 240: Marty AJ, Matar AF, Danielson R et al: The variation in hospital charges: a problem in determining cost/benefit for cardiac surgery. Ann Thorac Surg 1977; 112: Finkler SA: The distinction between cost and charges. Ann Intern Med 1982; 96: Gutman GM, Gee EM, Bojanowski BC et al: Fact Book on Aging, Gerontology Research Centre, Simon Fraser U, Burnaby, BC, 1986: Nuanheim KS, Fiore AC, Wadley JJ et al: The changing profile of the patient undergoing coronary artery bypass surgery. JAm Coll Cardiol 1988; 11: Christakis GT, Ivanov J, Weisel RD et al: The changing pattern of coronary artery bypass surgery. Circulation 1989; 80 (suppl 1): I Sheps SB, Gait J: A Study of Regional Trends in Isolated Coronary Artery Bypass Surgery and Percutaneous Transluminal Angioplasty in British Columbia, Dept of Health Care and Epidemiol, U of BC, Vancouver, a premisid Toro,sto). f y gible~~~~~ fo the -DEX fy-sv totye adiet ar et between the OMA and the~prvnilgvrmn,the final dat;e for acceptance of Malpracice Premium 1!lW.' : Reimbursement aplication,s wiis March 31, If yoieea na eiet in 1989, beiev a u ire ebnd notreiv an $ _ i have (Toroto) o l4o0268-7l5, e t. fl (,out- 168 CAN MED ASSOC J 1992; 146 (2)