CLINICAL AND COMMUNITY STUDIES ETUDES CLINIQUES ET COMMUNAUTAIRES
Recent trends in acute care hospital utilization in Ontario for diseases of the circulatory system Geoffrey M. Anderson, MD, PhD; Indra R. Pulcins, MA Objective: To describe trends in the use of acute care hospital services for diseases of the circulatory system in Ontario. Design: Observational study. Data extraction: Information on diagnoses, procedures and demographio characteristics was obtained from routinely collected computerized abstracts of separations from all acute care hospitals in Ontario during 1979-80, 1983-84 and 1988-89. The data were combined with population estimates to calculate overall separation rates and rates specific for age, diagnosis and procedure. Resource intensity weights were used to estimate changes in resource use. Main results: The overall separation rate increased by 3% and the resource-intensity-
weighted separation rate by 12% from 1979-80 to 1988-89. The overall medical separation rate increased by 2%, whereas the surgical rate increased by 12%. The surgical separation rate increased among patients 55 to 79 years of age but decreased in all the other adult age groups. The separation rates for coronary artery bypass surgery and cardiac valve surgery increased rapidly among patients 65 years of age or older. The medical separation rate decreased for patients of all ages except those less than 5 years and those 80 years or more. The medical separation rates decreased by less than 1% for diagnoses related to ischemic heart disease (IHD) and increased dramatically for coronary artery revascularization. Conclusions: The increasing elderly population has not resulted in large increases in acute care hospital utilization for diseases of the circulatory system. The impact of an aging population has been balanced by decreased utilization rates in the younger groups. The intensity of hospital care has risen primarily because of increases in surgical rates, especially in the elderly population. The large decrease in the rate of death from IHD over the past two decades has not been associated with similar decreases in acute care hospital utilization for this disorder.
Objectif: Decrire les tendances de l'utilisation des services hospitaliers de soins aigus dans les maladies de l'appareil circulatoire en Ontario. Conception: Etude par observation. Source des donnees: Les informations sur les diagnostics, les interventions et les caracteristiques demographiques sont tirees des resumes informatises de sorties collectes systematiquement dans tous les hopitaux de soins aigus de l'Ontario en 1979-1980, 1983-1984 et 1988-1989. Les donnees ont ete combinees a des estimations de la population pour calculer les taux de sorties et les taux particuliers a l'age, au diagnostic et a l'intervention. Des poids d'intensite ont ete affectes aux ressources pour estimer les changements quant a leur utilisation. Principaux resultats: Le taux global de sorties a augmente de 3 % et le taux de sorties
Dr. Anderson is associate director of the Health Policy Research Unit, Centre for Health Services and Policy Research, and assistant professor in the Department of Health Care and Epidemiology, University of British Columbia, Vancouver, BC. Ms. Pulcins is research associate at the Centre for Health Services and Policy Research, University of British Columbia, Vancouver, BC.
Reprint requests to: Dr. Geoffrey M. Anderson, Centre for Health Services and Policy Research, 429-2194 Health Sciences Mall, University of British Columbia, Vancouver, BC V6T 1Z6 AUGUST 1, 1991
CAN MED ASSOC J 1991; 145 (3)
221
pondere selon l'intensite des ressources a augmente de 12 % de 1979-1980 a 1988-1989. Le taux global de sorties en medecine a augmente de 2 %, alors qu'en chirurgie il s'est accru de 12 %. Le taux de sorties en chirurgie a augmente chez les malades de 55 a 79 ans, mais il a diminue dans tous les autres groupes d'age chez les adultes. Les taux de sorties des pontages aorto-coronariens et en chirurgie de remplacement valvulaire ont augmente rapidement chez les malades de 65 ans et plus. Le taux de sorties en medecine a diminue chez les malades de tout age, sauf les moins de 5 ans et les plus de 80 ans. Les taux de sorties en medecine ont diminue de moins de 1 % dans les diagnostics relies a la cardiopathie ischemique, et ils ont augmente enormement dans la revascularisation des arteres coronaires. Conclusions: L'accroissement de la population agee n'a pas provoque de hausses importantes dans l'utilisation des h6pitaux de soins aigus par rapport aux maladies de l'appareil circulatoire. L'incidence du vieillissement de la population a e compensde par une reduction des taux d'utilisation dans les groupes plus jeunes. L'intensite des soins hospitaliers a augmente surtout en raison de l'accroissement des taux en chirurgie, en particulier dans la population agee. L'importante diminution du taux de mortalite attribuable A la cardiopathie ischemique pendant les deux dernieres decennies ne correspond pas A des diminutions semblables dans l'utilisation des h6pitaux de soins aigus en ce qui concerne cette affection. iseases of the circulatory system are important causes of death and disability in Canada and are major contributors to health care utilization. Trends in the use of health care services, particularly high-technology services at acute care hospitals, have become the focus of much of the current health care policy debate. The purpose of this paper is to help clarify some important health policy issues through an examination of the trends in acute care hospital utilization for diseases of the circulatory system in general and ischemic heart disease (IHD) in particular. We used separation data from Ontario hospitals to provide a clinically meaningful context for examining (a) the impact of an aging population on acute care hospital utilization, (b) trends in accessibility of high-techD
nology services and (c) the impact of successful primary prevention on the use of acute care hospital services. The incidence and prevalence of diseases of the circulatory system increase with age. For example, the rate of death from IHD among people 65 years of age or older is almost 10 times the rate among those 35 to 64.' The disproportionate burden of circulatory diseases in the elderly combined with the rapid growth of the elderly population has led to the concern that the treatment of these and similar diseases will put increasing pressure on the acute care hospital system.2 Our analysis will provide an important example of the impact of an aging population on the health care system. Hospital-based treatment of circulatory diseases often involves complex technologies. Coronary artery bypass surgery (CABS) and open-heart valve surgery are two examples of the resource-intensive technologies that have become focal points for the debate over cost control and adequate access to health care, particulary for the elderly. Our analysis 222
CAN MED ASSOC J 1991; 145 (3)
will help to clarify some of the issues related to technology diffusion. Although the debate over access to hospitalbased technologies continues, there is growing support for the notion that future advances in health care may lie in disease prevention rather than treatment. Rates of death from IHD in Canada and the United States dropped dramatically through the 1970s and early 1980s.'3 It has been argued that much of those decreases were the result of primary prevention through changes in risk factors such as hypertension, smoking and hypercholesterolemia.45 How might this successful primary prevention effort likely affect acute care hospital utilization? If changes in risk factors have resulted in a decreased incidence of IHD, then the need for hospital services to treat IHD would be expected to decrease. However, if these changes have resulted in a decrease mostly in the disease-specific death rate rather than in incidence, then the need for hospital services might not be expected to decrease. Instead, the increased survival might lead to an increased need for hospital-based services. Although the results of this analysis cannot directly sort out the relative impacts of changes in incidence and disease-specific death rates, it can provide some information on the relation between the striking decrease in the rate of death from IHD and acute care hospital utilization for this disease.
Methods The data were obtained from the Hospital Medical Records Institute (HMRI). An abstract for every separation from an acute care hospital in Ontario is sent to the HMRI, where the data are edited and entered into a database. Each abstract provides information on the patient's age and place of resiLE I" AOUJT 1991
M--
dence, the diagnosis and the procedures performed. A computer algorithm that relies on the patient's age, primary diagnosis, complicating or comorbid diagnoses and procedures is used to assign each separation to a specific case mix group (CMG).6 The category "Diseases and Disorders of the Circulatory System" (major clinical category 5 [MCC-5]) consists of 42 CMGs, 18 surgical and 24 medical. MCC-5 includes separations for IHD, other diseases of the heart and peripheral vascular disease but excludes cerebrovascular disease. A complete list of the diagnoses and procedures used to define the separations assigned to MCC-5 and to the individual CMGs within MCC-5 can be obtained from the authors. Our analysis included all separations from acute care hospitals in Ontario for patients in MCC-5 for the fiscal years 1979-80, 1983-84 and 1988-89. We calculated overall and age-specific separation rates by dividing the number of separations by population data from the provincial government. The resource intensity was measured by multiplying CMG-specific separation rates by the resource intensity weight (RIW) assigned to that CMG. The RIWs were developed by the HMRI Database Committee to account for differences in average lengths of stay and costs per day across CMG categories. The resourceintensity-weighted discharge rate provided a method for measuring differences in the intensity of resource use for the different CMG categories. For example, CMG 141 (CABS with cardiac catheterization) has an RIW of 7.12, and CMG 157 (acute myocardial infarction without complications) has an RIW of 1.96.
Results
increased by about 2% over the study period, whereas the surgical rate increased by almost 12%. The overall resource-intensity-weighted separation rate increased by 12% over the study period. The resource-intensity-weighted medical separation rate increased by less than 3%, as compared with 35% for the resource-intensity-weighted surgical separation rate. In aggregate, the increase in the resource-intensity-weighted surgical separation rate accounted for over 80% of the increase in the overall resourceintensity-weighted separation rate. The greater increase in the resource-intensityweighted separation rate than in the separation rate itself indicated that the average intensity per separation (i.e., the resource-intensity-weighted separation rate divided by the separation rate) increased. This was particularly apparent for the surgical separations, for which the average intensity per separation increased by 20% from 1979-80 to 1988-89. During the study period the surgical separation rates increased among those 14 years of age or younger and those 55 to 79 years (Fig. 1); the increases were by 32% among those 4 years of age or less, by 8% among those 5 to 14, by 9% among those 55 to 64, by 16% among those 65 to 69, by 25% among those 70 to 74 and by 15% among those 75 to 79. The surgical separation rates decreased by 4% among those 15 to 24 years, by 27% among those 25 to 34, by 24% among those 35 to 44 years and by 7% among those 45 to 54. The medical separation rate decreased in every age group except the youngest and oldest ones (Fig. 2): the rates decreased by 26% among those 35 to 44 years of age, by 19% among those 45 to 54 years and by 9% among those 55 to 64 years.
In 1988-89 the nine CMGs listed in Table 2 The separation rate for diseases of the circulato- accounted for about 60% of all surgical separations ry system increased by about 3% from 1979-80 to 1988-89 (Table 1). The medical separation rate 1200
Table 1: Separation rates per 100000 population for diseases of the circulatory system in Ontario from 1979-80 to 1988-89 by type of service Year; type of service 1979-80 Surgical Medical Total 1983-84 Surgical Medical Total 1988-89 Surgical Medical Total AUGUST 1, 1991
Separation
Resource-intensityweighted separation
rate
rate
1000'
9
800600-
400
222.4 1277.4 1499.8
607.7 1500.0 2107.7
240.8 1314.4 1555.2
727.0
20:0
85
Table 3: Separation rates per 100 000 population for selected medical CMGs
Separation rate CMG Myocardial infarction (CMGs 156-157) Heart failure and shock (CMG 162) Cardiac arrest (CMG 164) Atherosclerosis (CMGs 167-168) Cardiac arrhythmia (CMGs 173-174) Angina pectoris and chest pain (CMGs 175, 179) Total .AUGUST 1, 1991
1979-80 219.0 147.6 5.8 212.5 93.2
1983-84 212.1 159.8 6.0 170.7 107.1
1988-89 205.3 192.5 5.2 122.4 119.2
148.0 826.1
198.8 854.5
177.0 821.6
CAN MED ASSOC J 1991; 145 (3)
225
increase in the intensity per surgical separation. This general shift to more resource-intensive procedures reflects the increased use of specific high-technology procedures such as CABS, open-heart valve surgery and angioplasty. The increased rates of surgery for conditions in MCC-5 in Ontario have been consistent with the rates in other provinces9 and, except for CABS, with MCC-5 surgery rates in the United States.10 In our study, although the age-specific rates for CABS and open-heart valve surgery (two of the most resource-intensive procedures) increased rapidly among the elderly, particularly those 70 to 79 years of age, the rates decreased among adults less than 55 years of age. Thus, increased access to these procedures, although not equally distributed, was focused in the elderly population. The demonstrated increased access to these high-technology procedures among the elderly should address some of the concerns that cost controls in the Canadian health care system might severely restrict care for that age group. However, the benefits of increased access among the elderly and concomitant decreased utilization in other age groups raise other issues, specifically quality of care. The trade-off between the immediate risk of death from surgery and the possibility of long-term benefits in quality or quantity of life for those who undergo such procedures as CABS may be sensitive to age." Elderly patients who are at greater risk for death and disability from surgery and who may have fewer quality-adjusted life years to gain than younger patients may not be the best target group for these procedures. Clearly the increasing reliance on these procedures for the elderly, particulary the "old old," deserves further scrutiny. Our results showed a rapid increase in the rates of use of CABS and percutaneous transluminal coronary angioplasty, the two main surgical procedures used to treat IHD. However, most of the patients with IHD admitted to hospital receive medical, not surgical, treatment. In 1988 there were over 13 times more separations for the 10 medical CMGs associated with IHD than for these two surgical procedures. Thus, although there was a rapid increase in surgical care for IHD, the stable medical separation rate resulted in a relatively stable overall separation rate for IHD. The stable utilization rate in the face of successful primary prevention of death from IHD is consistent with the view that primary prevention may not be a useful strategy for controlling health care costs.'2 However, the lack of a major impact of primary prevention on utilization noted in this study is open to other, more encouraging interpretations. The decreased rate of death from IHD may reflect not a decreased incidence of the disease but, rather, a decreased case-fatality rate, which could have result226
CAN MED ASSOC J 1991; 145 (3)
ed in an increased need for hospital-based services. Similarly, the decreased death rate could be due in part to hospital-based interventions such as improved medical care for myocardial infarction and successful revascularization surgery. Successful primary prevention does not preclude improvements in secondary prevention. Also, the impact of primary prevention on utilization may be delayed. Although the decreased rate of death from IHD was relatively evenly distributed across the age groups,' the decrease in the separation rate was limited to the nonelderly. This is consistent with the limiting of benefits to a particular birth cohort. If the benefit is cohort related, then separation rates among the elderly might be expected to decrease in future. Reductions in incidence in all age groups could eventually lead to decreases in overall levels of hospital utilization. This study was supported by grant 02024 from the Ontario Ministry of Health. The Health Policy Research Unit is supported by grants from the Woodward and Vancouver foundations and the British Columbia Ministry of Health. Dr. Anderson was supported by the British Columbia Health Care Research Foundation.
References 1. Nicholls ES, Jung J, Davies JW: Cardiovascular disease mortality in Canada. Can Med Assoc J 1981; 125: 981-992 2. Boulet JA, Grenier G: Health Expenditures in Canada and the Impact of Demographic Changes on Future Government Health Insurance Program Expenditures (discussion paper
123), Economic Council of Canada, Ottawa, 1978: 50-71 3. Stern MPL: The recent decline in ischemic heart disease mortality. Ann Intern Med 1979; 91: 630-640 4. Sytkowski PA, Kannel WB, D'Agostino RB: Changes in risk factors and the decline in mortality from cardiovascular disease. N Engl J Med 1990; 322: 1635-1641 5. Goldman L, Cook EF: The decline in ischemic heart disease mortality rates: an analysis of the comparative effects of medical interventions and changes in lifestyle. Ann Intern Med 1984; 101: 825-836 6. MacKenzie TA, Markle F, Croke M: CMG's: variations on a theme. Health Manage Forum 1987; 8 (1): 21-24 7. Intercensal Annual Estimates of Population by Age and Sex for Canada and the Provinces, 1976-81 (cat 91-518), Statistics Canada, Ottawa, 1983 8. Postcensal Annual Estimates ofPopulations by Marital Status, Age, Sex and Components of Growth for Canada, the Provinces and the Territories, June 1, 1988 (cat 91-210), vol 6, Statistics Canada, Ottawa, 1988 9. Roos LL, Fisher ES, Sharp SM et al: Postsurgical mortality in Manitoba and New England. JAMA 1990; 263: 2453-2458 10. Anderson GM, Newhouse JP, Roos LL: Hospital care for elderly patients with diseases of the circulatory system: a comparison of hospital use in the United States and Canada. N Engl J Med 1989; 321: 1443-1448 11. Anderson GM, Lomas J: Monitoring the diffusion of a technology: coronary artery bypass surgery in Ontario. Am J Public Health 1988; 78: 251-254 12. Russell LB: Is Prevention Better than Cure?9, Brookings, Washington, 1986: 2-3 LE Ier AOUT 1991
Recent trends in acute care hospital utilization in Ontario for diseases of the circulatory system Geoffrey M. Anderson, MD, PhD; Indra R. Pulcins, MA Objective: To describe trends in the use of acute care hospital services for diseases of the circulatory system in Ontario. Design: Observational study. Data extraction: Information on diagnoses, procedures and demographio characteristics was obtained from routinely collected computerized abstracts of separations from all acute care hospitals in Ontario during 1979-80, 1983-84 and 1988-89. The data were combined with population estimates to calculate overall separation rates and rates specific for age, diagnosis and procedure. Resource intensity weights were used to estimate changes in resource use. Main results: The overall separation rate increased by 3% and the resource-intensity-
weighted separation rate by 12% from 1979-80 to 1988-89. The overall medical separation rate increased by 2%, whereas the surgical rate increased by 12%. The surgical separation rate increased among patients 55 to 79 years of age but decreased in all the other adult age groups. The separation rates for coronary artery bypass surgery and cardiac valve surgery increased rapidly among patients 65 years of age or older. The medical separation rate decreased for patients of all ages except those less than 5 years and those 80 years or more. The medical separation rates decreased by less than 1% for diagnoses related to ischemic heart disease (IHD) and increased dramatically for coronary artery revascularization. Conclusions: The increasing elderly population has not resulted in large increases in acute care hospital utilization for diseases of the circulatory system. The impact of an aging population has been balanced by decreased utilization rates in the younger groups. The intensity of hospital care has risen primarily because of increases in surgical rates, especially in the elderly population. The large decrease in the rate of death from IHD over the past two decades has not been associated with similar decreases in acute care hospital utilization for this disorder.
Objectif: Decrire les tendances de l'utilisation des services hospitaliers de soins aigus dans les maladies de l'appareil circulatoire en Ontario. Conception: Etude par observation. Source des donnees: Les informations sur les diagnostics, les interventions et les caracteristiques demographiques sont tirees des resumes informatises de sorties collectes systematiquement dans tous les hopitaux de soins aigus de l'Ontario en 1979-1980, 1983-1984 et 1988-1989. Les donnees ont ete combinees a des estimations de la population pour calculer les taux de sorties et les taux particuliers a l'age, au diagnostic et a l'intervention. Des poids d'intensite ont ete affectes aux ressources pour estimer les changements quant a leur utilisation. Principaux resultats: Le taux global de sorties a augmente de 3 % et le taux de sorties
Dr. Anderson is associate director of the Health Policy Research Unit, Centre for Health Services and Policy Research, and assistant professor in the Department of Health Care and Epidemiology, University of British Columbia, Vancouver, BC. Ms. Pulcins is research associate at the Centre for Health Services and Policy Research, University of British Columbia, Vancouver, BC.
Reprint requests to: Dr. Geoffrey M. Anderson, Centre for Health Services and Policy Research, 429-2194 Health Sciences Mall, University of British Columbia, Vancouver, BC V6T 1Z6 AUGUST 1, 1991
CAN MED ASSOC J 1991; 145 (3)
221
pondere selon l'intensite des ressources a augmente de 12 % de 1979-1980 a 1988-1989. Le taux global de sorties en medecine a augmente de 2 %, alors qu'en chirurgie il s'est accru de 12 %. Le taux de sorties en chirurgie a augmente chez les malades de 55 a 79 ans, mais il a diminue dans tous les autres groupes d'age chez les adultes. Les taux de sorties des pontages aorto-coronariens et en chirurgie de remplacement valvulaire ont augmente rapidement chez les malades de 65 ans et plus. Le taux de sorties en medecine a diminue chez les malades de tout age, sauf les moins de 5 ans et les plus de 80 ans. Les taux de sorties en medecine ont diminue de moins de 1 % dans les diagnostics relies a la cardiopathie ischemique, et ils ont augmente enormement dans la revascularisation des arteres coronaires. Conclusions: L'accroissement de la population agee n'a pas provoque de hausses importantes dans l'utilisation des h6pitaux de soins aigus par rapport aux maladies de l'appareil circulatoire. L'incidence du vieillissement de la population a e compensde par une reduction des taux d'utilisation dans les groupes plus jeunes. L'intensite des soins hospitaliers a augmente surtout en raison de l'accroissement des taux en chirurgie, en particulier dans la population agee. L'importante diminution du taux de mortalite attribuable A la cardiopathie ischemique pendant les deux dernieres decennies ne correspond pas A des diminutions semblables dans l'utilisation des h6pitaux de soins aigus en ce qui concerne cette affection. iseases of the circulatory system are important causes of death and disability in Canada and are major contributors to health care utilization. Trends in the use of health care services, particularly high-technology services at acute care hospitals, have become the focus of much of the current health care policy debate. The purpose of this paper is to help clarify some important health policy issues through an examination of the trends in acute care hospital utilization for diseases of the circulatory system in general and ischemic heart disease (IHD) in particular. We used separation data from Ontario hospitals to provide a clinically meaningful context for examining (a) the impact of an aging population on acute care hospital utilization, (b) trends in accessibility of high-techD
nology services and (c) the impact of successful primary prevention on the use of acute care hospital services. The incidence and prevalence of diseases of the circulatory system increase with age. For example, the rate of death from IHD among people 65 years of age or older is almost 10 times the rate among those 35 to 64.' The disproportionate burden of circulatory diseases in the elderly combined with the rapid growth of the elderly population has led to the concern that the treatment of these and similar diseases will put increasing pressure on the acute care hospital system.2 Our analysis will provide an important example of the impact of an aging population on the health care system. Hospital-based treatment of circulatory diseases often involves complex technologies. Coronary artery bypass surgery (CABS) and open-heart valve surgery are two examples of the resource-intensive technologies that have become focal points for the debate over cost control and adequate access to health care, particulary for the elderly. Our analysis 222
CAN MED ASSOC J 1991; 145 (3)
will help to clarify some of the issues related to technology diffusion. Although the debate over access to hospitalbased technologies continues, there is growing support for the notion that future advances in health care may lie in disease prevention rather than treatment. Rates of death from IHD in Canada and the United States dropped dramatically through the 1970s and early 1980s.'3 It has been argued that much of those decreases were the result of primary prevention through changes in risk factors such as hypertension, smoking and hypercholesterolemia.45 How might this successful primary prevention effort likely affect acute care hospital utilization? If changes in risk factors have resulted in a decreased incidence of IHD, then the need for hospital services to treat IHD would be expected to decrease. However, if these changes have resulted in a decrease mostly in the disease-specific death rate rather than in incidence, then the need for hospital services might not be expected to decrease. Instead, the increased survival might lead to an increased need for hospital-based services. Although the results of this analysis cannot directly sort out the relative impacts of changes in incidence and disease-specific death rates, it can provide some information on the relation between the striking decrease in the rate of death from IHD and acute care hospital utilization for this disease.
Methods The data were obtained from the Hospital Medical Records Institute (HMRI). An abstract for every separation from an acute care hospital in Ontario is sent to the HMRI, where the data are edited and entered into a database. Each abstract provides information on the patient's age and place of resiLE I" AOUJT 1991
M--
dence, the diagnosis and the procedures performed. A computer algorithm that relies on the patient's age, primary diagnosis, complicating or comorbid diagnoses and procedures is used to assign each separation to a specific case mix group (CMG).6 The category "Diseases and Disorders of the Circulatory System" (major clinical category 5 [MCC-5]) consists of 42 CMGs, 18 surgical and 24 medical. MCC-5 includes separations for IHD, other diseases of the heart and peripheral vascular disease but excludes cerebrovascular disease. A complete list of the diagnoses and procedures used to define the separations assigned to MCC-5 and to the individual CMGs within MCC-5 can be obtained from the authors. Our analysis included all separations from acute care hospitals in Ontario for patients in MCC-5 for the fiscal years 1979-80, 1983-84 and 1988-89. We calculated overall and age-specific separation rates by dividing the number of separations by population data from the provincial government. The resource intensity was measured by multiplying CMG-specific separation rates by the resource intensity weight (RIW) assigned to that CMG. The RIWs were developed by the HMRI Database Committee to account for differences in average lengths of stay and costs per day across CMG categories. The resourceintensity-weighted discharge rate provided a method for measuring differences in the intensity of resource use for the different CMG categories. For example, CMG 141 (CABS with cardiac catheterization) has an RIW of 7.12, and CMG 157 (acute myocardial infarction without complications) has an RIW of 1.96.
Results
increased by about 2% over the study period, whereas the surgical rate increased by almost 12%. The overall resource-intensity-weighted separation rate increased by 12% over the study period. The resource-intensity-weighted medical separation rate increased by less than 3%, as compared with 35% for the resource-intensity-weighted surgical separation rate. In aggregate, the increase in the resource-intensity-weighted surgical separation rate accounted for over 80% of the increase in the overall resourceintensity-weighted separation rate. The greater increase in the resource-intensityweighted separation rate than in the separation rate itself indicated that the average intensity per separation (i.e., the resource-intensity-weighted separation rate divided by the separation rate) increased. This was particularly apparent for the surgical separations, for which the average intensity per separation increased by 20% from 1979-80 to 1988-89. During the study period the surgical separation rates increased among those 14 years of age or younger and those 55 to 79 years (Fig. 1); the increases were by 32% among those 4 years of age or less, by 8% among those 5 to 14, by 9% among those 55 to 64, by 16% among those 65 to 69, by 25% among those 70 to 74 and by 15% among those 75 to 79. The surgical separation rates decreased by 4% among those 15 to 24 years, by 27% among those 25 to 34, by 24% among those 35 to 44 years and by 7% among those 45 to 54. The medical separation rate decreased in every age group except the youngest and oldest ones (Fig. 2): the rates decreased by 26% among those 35 to 44 years of age, by 19% among those 45 to 54 years and by 9% among those 55 to 64 years.
In 1988-89 the nine CMGs listed in Table 2 The separation rate for diseases of the circulato- accounted for about 60% of all surgical separations ry system increased by about 3% from 1979-80 to 1988-89 (Table 1). The medical separation rate 1200
Table 1: Separation rates per 100000 population for diseases of the circulatory system in Ontario from 1979-80 to 1988-89 by type of service Year; type of service 1979-80 Surgical Medical Total 1983-84 Surgical Medical Total 1988-89 Surgical Medical Total AUGUST 1, 1991
Separation
Resource-intensityweighted separation
rate
rate
1000'
9
800600-
400
222.4 1277.4 1499.8
607.7 1500.0 2107.7
240.8 1314.4 1555.2
727.0
20:0
85
Table 3: Separation rates per 100 000 population for selected medical CMGs
Separation rate CMG Myocardial infarction (CMGs 156-157) Heart failure and shock (CMG 162) Cardiac arrest (CMG 164) Atherosclerosis (CMGs 167-168) Cardiac arrhythmia (CMGs 173-174) Angina pectoris and chest pain (CMGs 175, 179) Total .AUGUST 1, 1991
1979-80 219.0 147.6 5.8 212.5 93.2
1983-84 212.1 159.8 6.0 170.7 107.1
1988-89 205.3 192.5 5.2 122.4 119.2
148.0 826.1
198.8 854.5
177.0 821.6
CAN MED ASSOC J 1991; 145 (3)
225
increase in the intensity per surgical separation. This general shift to more resource-intensive procedures reflects the increased use of specific high-technology procedures such as CABS, open-heart valve surgery and angioplasty. The increased rates of surgery for conditions in MCC-5 in Ontario have been consistent with the rates in other provinces9 and, except for CABS, with MCC-5 surgery rates in the United States.10 In our study, although the age-specific rates for CABS and open-heart valve surgery (two of the most resource-intensive procedures) increased rapidly among the elderly, particularly those 70 to 79 years of age, the rates decreased among adults less than 55 years of age. Thus, increased access to these procedures, although not equally distributed, was focused in the elderly population. The demonstrated increased access to these high-technology procedures among the elderly should address some of the concerns that cost controls in the Canadian health care system might severely restrict care for that age group. However, the benefits of increased access among the elderly and concomitant decreased utilization in other age groups raise other issues, specifically quality of care. The trade-off between the immediate risk of death from surgery and the possibility of long-term benefits in quality or quantity of life for those who undergo such procedures as CABS may be sensitive to age." Elderly patients who are at greater risk for death and disability from surgery and who may have fewer quality-adjusted life years to gain than younger patients may not be the best target group for these procedures. Clearly the increasing reliance on these procedures for the elderly, particulary the "old old," deserves further scrutiny. Our results showed a rapid increase in the rates of use of CABS and percutaneous transluminal coronary angioplasty, the two main surgical procedures used to treat IHD. However, most of the patients with IHD admitted to hospital receive medical, not surgical, treatment. In 1988 there were over 13 times more separations for the 10 medical CMGs associated with IHD than for these two surgical procedures. Thus, although there was a rapid increase in surgical care for IHD, the stable medical separation rate resulted in a relatively stable overall separation rate for IHD. The stable utilization rate in the face of successful primary prevention of death from IHD is consistent with the view that primary prevention may not be a useful strategy for controlling health care costs.'2 However, the lack of a major impact of primary prevention on utilization noted in this study is open to other, more encouraging interpretations. The decreased rate of death from IHD may reflect not a decreased incidence of the disease but, rather, a decreased case-fatality rate, which could have result226
CAN MED ASSOC J 1991; 145 (3)
ed in an increased need for hospital-based services. Similarly, the decreased death rate could be due in part to hospital-based interventions such as improved medical care for myocardial infarction and successful revascularization surgery. Successful primary prevention does not preclude improvements in secondary prevention. Also, the impact of primary prevention on utilization may be delayed. Although the decreased rate of death from IHD was relatively evenly distributed across the age groups,' the decrease in the separation rate was limited to the nonelderly. This is consistent with the limiting of benefits to a particular birth cohort. If the benefit is cohort related, then separation rates among the elderly might be expected to decrease in future. Reductions in incidence in all age groups could eventually lead to decreases in overall levels of hospital utilization. This study was supported by grant 02024 from the Ontario Ministry of Health. The Health Policy Research Unit is supported by grants from the Woodward and Vancouver foundations and the British Columbia Ministry of Health. Dr. Anderson was supported by the British Columbia Health Care Research Foundation.
References 1. Nicholls ES, Jung J, Davies JW: Cardiovascular disease mortality in Canada. Can Med Assoc J 1981; 125: 981-992 2. Boulet JA, Grenier G: Health Expenditures in Canada and the Impact of Demographic Changes on Future Government Health Insurance Program Expenditures (discussion paper
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