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The cost effectiveness of total joint replacement: the Canadian experience
Abstracts
/ The kkee 3 (I996)
Li S, Burstein AH. Current concepts review. Ultra-high molecular weight polyethylene. J Bone Joint Surg 1994:76A;108G1090. 161 Wright TM, Rimnac CM. Ultra-high molecular weight polyethylene. In: Morrey B, ed. Joint Replacement Arthroplasty, New York, NY: Churchill Livingstone, Chapter 5, 1991337-45. [71 Rimnac CM, Klein RW et al. Post-irradiation agin,g of ultra high molecular weight polyethylene. J Bone Joint Surg 1994:76A:1052-1055. @I Oonishi H. Aono M et al. Alumina versus polyethylene in total knee arthroplasty. Clin Orthop Rel Res 1992:?82;95--104. [91 White SE, Whiteside LA et al. Simulated knee wear with cobalt chromium and oxidized zirconium knee femoral components. Clin Orthop Rel Res 1994;309:176-184.
El
The cost effectiveness of total joint replacement: the Canadian experience RB Boume University Hospital, Division of Orthopaedic Surgery, University of Western Ontario, L,ondon, Ontario, Canada John Charnley is considered the father of contemporary total hip replacement. Since his pioneering work, more than six million total hip replacements have been inserted worldwide. Although the benefits of total hip replacements seem self-evident, contemporaq; forces have prompted an examination of all common medical procedures. The cost of health care financing has become an issue in each country of the world. In Canada, health care expenditures are increasing at an alarming rate and in 1993, represented sixty-seven billion dollars of 9.9% of our gross domestic product. The reasonsfor this cost escalation have been blamed on an aging population as well as other factors such as inflation, affluence \ and geater patient choices. Currently patients over 6.5years of age consume 40% of our heaIth care budget. As the post-war baby population ages, the percent of patients over 65 will increase and so will costs. In 1990 Ontario Health Survey examined 4.5650 patients over the age of 16 ylears for prevalence disease.Arthritis was identified in 19% overall, with the prevalence being 6% in patients aged 16-25 years and a staggering 51% in those over 7.5 years. Arthritis was identified as a leading cause of long term disability, chronic health problems and the need for prescription drugs and seeking health professional. Similar studies have also examined various populations for total joint replacement rates. Comparisonsbetween the United Kingdom and Canada have revealed that our total hip and total knee replacement rates are Ilower in Canada with considerable variation from one country to another. This led our health care providers to investigate initiatives to increase total joint replacement rates in our province. In 3986, we initiated a study to determine the effect of total hip replacement on health related quality of life and also attempted an assessmentof the cost benefit of total hip replacement. At the time, we looked upon ourselves as advocates for the elderly, not anticipating the health care crisis in which we now find ourselves. Between 1988 and 1991,250 patients were entere.d into a double blind, randomized clinical trial comparing cemented versus cementless total hip replacements. Osteoarthritic patients were included of a Charnley Type A
155-I
161
75
Table 1 Total joint replacement eligibility in UK 55 years ,THR l TKR
49.8 per thousand 16.4 per thousand
functional category. Patients were assessedpre-operatively and post-operatively using diseasespecific, patient specific, global, functional capacity and cost to utility outcome measures. Cost to quality adjusted life year data was collected and compared to other medical and surgical interventions. Rest& (a) Diseasespecific outcome measures:The Harris Hip Score and D’Aubigne assessmenttools represent examples of diseasespecific outcome measures. With both, patients benefitted greatly from total hip replacement with no apparent difference being detected between cemented and cementlesstotal hip replacements. (b) Patient specific outcome measures:The MACTAR outcome measure represents a patient specific assessment. Using this scale, the patient lists the top five reasonswhy he or she underwent total hip replacement and then assesses their outcome utilizing a visual analogue scale. Once again, one will note the marked improvement from total hip replacement with no apparent difference between cemented and cementlessimplants. (c) Global outcome measures:At the time of this study, the Sickness Impact Profile (SIP) represented a global outcome measure which examined twelve dimensionsof patient health. The first discovery by our epidemiologist was the profound disability of patient with osteoarthritis of the hip. The scores achieved were similar to patients with intractable angina on haemodialysis or awaiting transplantation surgery. Unlike these other conditions, h4 rthritic patients treated with total hip replacement were v&ally reverted to normal health. Once again, there wai no difference between the cemented and cementless devices. (d) Functional capacity: The six minute walk was used as a measure of functional capacity. Patients benefitted greatly from total hip replacement and once again no significan difference was noted between cemented and cementles ! devices. (e) Cost to utility assessment:In an effort to combine improvement with costing, two additional piecesof information were required. To determine the clinical improvement, the Time Trade-off was utilized in which patient improvement could be assessed on a scalefrom 0 to 1. Zero represented virtual death and 1 perfect health. One will note that total hip replacement resulted in impressive patient improvement. From these figures, an improvement in the clinical status of the patient could be given a number. Table 2 THR and TKR rates per thousand in Ontario
Ontario Oxford East York
THR
TKR
7.7 10.4 5.0
5.8 10.9 4.2
162
Abstracts
/ The Knee 3 (1996)
This was combined with accurate costing data. At the time of this study, hospitals knew what they charged for total hip replacement but had very little information on costing. Two graduate students accurately costed both cemented and cementless total hip replacements at our institution and found that we could do each for approximately $10000 Canadian including all hospital and physician charges. This data was then combined with the time trade-off data to produce cost to quality adjusted life year data. We also collected the hip related cost to society of the patient and third parties for years one and two post-operatively, utilizing a detailed diary system. At two years post-operatively, the cost to QALY ratio was approximately $8200. We then compared this cost to QALY outcome data with other common medical surgical interventions. Laupacis et al. have developed a cost to QALY gradient to determine the cost effectiveness of various medical interventions. These interventions which are under $20000 are considered so cost effective that this intervention should be questioned. Interventions costing between $20001 and $100000 are moderately cost effective and probably should be funded. Those interventions over $100001 might be efficacious but are extremely expensive. Their adoption into clinical practice requires considerable discussion and analysis. Based on this assessment, it is obvious that total hip replacement represents one of the most cost effective medical and surgical interventions known. Summa y All medical endeavours are under considerable scrutiny in the 1990s. The issues of cost effectiveness and quality assurance are extremely important. The power of accurate outcome research cannot be overestimated in terms of supporting, validating and advancing medical patients. In this context, we can make the following observations: (1) In up to eight years follow up, no difference in clinical outcomes has been noted when comparing the cemented and cementless total hip replacements analyzed in this study. (2) Patients with severe osteoarthritis of their hip are just as disabled as those with so-called life threatening illnesses. (3) Total hip replacement represents one of the most cost effective medical interventions known. Deep vein thrombosis screening after TKR Venography vs Dopplers Steven B. Haas The Hospital for Special Surgery, New York, NY, USA I. Overview A. Deep-vein thrombosis (DVT) and pulmonary emboli (PEj remain one of the most serious and common complication following orthopaedic surgery II. Incidence of DVT and PE after total knee arthroplas A. D% T--No nroDhvkis 1. Venograihic’al& detected DVT: 65-88% 2. Proximal DVT: 3-20% B. DVT-l+?th prophylaxis 1. Aspirin: 41-73% 2. Warfarin: 24-69% 3. Pneumatic compression: lo-33% 17-45% 4. LMWH:
I55-175
III. Definition A. B.
of terms
Primary prophylaxis-preventing the occurrence of aDVT Secondary prophylaxis-preventing DVT from embolizing and preventing or identifying propagation
IV. Why is secondary prophylaxis important? Despite prophylaxis DVT occur Up to 50% of large proximal thrombi may embolize 3. Up to 24% of calf thrombi may propagate to the proximal veins. Calf thrombi is also associated with increased rates of symptomatic and asymtomatic PE ::
PE: (Haas et al., JBJS-B 1992) No Thrombi Calf Thrombi
Asymptotic PE ~~
Symptomatic FE: 0.2% 1.6%
V. Strategies for DVT prophylaxis A. B.
Use an effective primary prophylactic modalities in ALL patients Alternatives for post discharge management and secondary prophylaxis 1. Continue prophylaxis after discharge in ALL patients 2. Screen all patients: Treat or re-screen patients with DVT 3. Discontinue prophylaxis at discharge without screening
VI. What is best method to screen and detect deep vein thrombosis? A.
Clinical presentation-highly variable 1. Most DVT are asymptomatic 2. May be generalized including calf pain, leg swelling fever 3. Clinical exam unreliable for detection of DVT B. Venography-Contrast agent (ionic or non-ionic) is injected into the veins of the foot and under fluoroscopic monitoring X-ray are taken of the lower extremity. Advantages 1. Direct visualization of the thrombi (seen as a filling defect) 2. Sensitive for both proximal and distal DVT Disadvantage 1, Venous access must be obtained in the foot with risk of extravasation 2. Anaphylactoid reaction to contrast agent 3. Has been reported to precipitate thrombosis 4. Does not visualize deep femoral vein or internal iliac vein 5. Expensive C. B-mode Ultrasowzd-Several criteria used to detect thrombi including: l visualization of thrombi . inability to compress vein . percentage change in vein diameter during Valsalva maneuver Advantages 1. Non-invasive 2. No radiation exposure
/ The kkee 3 (I996)
Li S, Burstein AH. Current concepts review. Ultra-high molecular weight polyethylene. J Bone Joint Surg 1994:76A;108G1090. 161 Wright TM, Rimnac CM. Ultra-high molecular weight polyethylene. In: Morrey B, ed. Joint Replacement Arthroplasty, New York, NY: Churchill Livingstone, Chapter 5, 1991337-45. [71 Rimnac CM, Klein RW et al. Post-irradiation agin,g of ultra high molecular weight polyethylene. J Bone Joint Surg 1994:76A:1052-1055. @I Oonishi H. Aono M et al. Alumina versus polyethylene in total knee arthroplasty. Clin Orthop Rel Res 1992:?82;95--104. [91 White SE, Whiteside LA et al. Simulated knee wear with cobalt chromium and oxidized zirconium knee femoral components. Clin Orthop Rel Res 1994;309:176-184.
El
The cost effectiveness of total joint replacement: the Canadian experience RB Boume University Hospital, Division of Orthopaedic Surgery, University of Western Ontario, L,ondon, Ontario, Canada John Charnley is considered the father of contemporary total hip replacement. Since his pioneering work, more than six million total hip replacements have been inserted worldwide. Although the benefits of total hip replacements seem self-evident, contemporaq; forces have prompted an examination of all common medical procedures. The cost of health care financing has become an issue in each country of the world. In Canada, health care expenditures are increasing at an alarming rate and in 1993, represented sixty-seven billion dollars of 9.9% of our gross domestic product. The reasonsfor this cost escalation have been blamed on an aging population as well as other factors such as inflation, affluence \ and geater patient choices. Currently patients over 6.5years of age consume 40% of our heaIth care budget. As the post-war baby population ages, the percent of patients over 65 will increase and so will costs. In 1990 Ontario Health Survey examined 4.5650 patients over the age of 16 ylears for prevalence disease.Arthritis was identified in 19% overall, with the prevalence being 6% in patients aged 16-25 years and a staggering 51% in those over 7.5 years. Arthritis was identified as a leading cause of long term disability, chronic health problems and the need for prescription drugs and seeking health professional. Similar studies have also examined various populations for total joint replacement rates. Comparisonsbetween the United Kingdom and Canada have revealed that our total hip and total knee replacement rates are Ilower in Canada with considerable variation from one country to another. This led our health care providers to investigate initiatives to increase total joint replacement rates in our province. In 3986, we initiated a study to determine the effect of total hip replacement on health related quality of life and also attempted an assessmentof the cost benefit of total hip replacement. At the time, we looked upon ourselves as advocates for the elderly, not anticipating the health care crisis in which we now find ourselves. Between 1988 and 1991,250 patients were entere.d into a double blind, randomized clinical trial comparing cemented versus cementless total hip replacements. Osteoarthritic patients were included of a Charnley Type A
155-I
161
75
Table 1 Total joint replacement eligibility in UK 55 years ,THR l TKR
49.8 per thousand 16.4 per thousand
functional category. Patients were assessedpre-operatively and post-operatively using diseasespecific, patient specific, global, functional capacity and cost to utility outcome measures. Cost to quality adjusted life year data was collected and compared to other medical and surgical interventions. Rest& (a) Diseasespecific outcome measures:The Harris Hip Score and D’Aubigne assessmenttools represent examples of diseasespecific outcome measures. With both, patients benefitted greatly from total hip replacement with no apparent difference being detected between cemented and cementlesstotal hip replacements. (b) Patient specific outcome measures:The MACTAR outcome measure represents a patient specific assessment. Using this scale, the patient lists the top five reasonswhy he or she underwent total hip replacement and then assesses their outcome utilizing a visual analogue scale. Once again, one will note the marked improvement from total hip replacement with no apparent difference between cemented and cementlessimplants. (c) Global outcome measures:At the time of this study, the Sickness Impact Profile (SIP) represented a global outcome measure which examined twelve dimensionsof patient health. The first discovery by our epidemiologist was the profound disability of patient with osteoarthritis of the hip. The scores achieved were similar to patients with intractable angina on haemodialysis or awaiting transplantation surgery. Unlike these other conditions, h4 rthritic patients treated with total hip replacement were v&ally reverted to normal health. Once again, there wai no difference between the cemented and cementless devices. (d) Functional capacity: The six minute walk was used as a measure of functional capacity. Patients benefitted greatly from total hip replacement and once again no significan difference was noted between cemented and cementles ! devices. (e) Cost to utility assessment:In an effort to combine improvement with costing, two additional piecesof information were required. To determine the clinical improvement, the Time Trade-off was utilized in which patient improvement could be assessed on a scalefrom 0 to 1. Zero represented virtual death and 1 perfect health. One will note that total hip replacement resulted in impressive patient improvement. From these figures, an improvement in the clinical status of the patient could be given a number. Table 2 THR and TKR rates per thousand in Ontario
Ontario Oxford East York
THR
TKR
7.7 10.4 5.0
5.8 10.9 4.2
162
Abstracts
/ The Knee 3 (1996)
This was combined with accurate costing data. At the time of this study, hospitals knew what they charged for total hip replacement but had very little information on costing. Two graduate students accurately costed both cemented and cementless total hip replacements at our institution and found that we could do each for approximately $10000 Canadian including all hospital and physician charges. This data was then combined with the time trade-off data to produce cost to quality adjusted life year data. We also collected the hip related cost to society of the patient and third parties for years one and two post-operatively, utilizing a detailed diary system. At two years post-operatively, the cost to QALY ratio was approximately $8200. We then compared this cost to QALY outcome data with other common medical surgical interventions. Laupacis et al. have developed a cost to QALY gradient to determine the cost effectiveness of various medical interventions. These interventions which are under $20000 are considered so cost effective that this intervention should be questioned. Interventions costing between $20001 and $100000 are moderately cost effective and probably should be funded. Those interventions over $100001 might be efficacious but are extremely expensive. Their adoption into clinical practice requires considerable discussion and analysis. Based on this assessment, it is obvious that total hip replacement represents one of the most cost effective medical and surgical interventions known. Summa y All medical endeavours are under considerable scrutiny in the 1990s. The issues of cost effectiveness and quality assurance are extremely important. The power of accurate outcome research cannot be overestimated in terms of supporting, validating and advancing medical patients. In this context, we can make the following observations: (1) In up to eight years follow up, no difference in clinical outcomes has been noted when comparing the cemented and cementless total hip replacements analyzed in this study. (2) Patients with severe osteoarthritis of their hip are just as disabled as those with so-called life threatening illnesses. (3) Total hip replacement represents one of the most cost effective medical interventions known. Deep vein thrombosis screening after TKR Venography vs Dopplers Steven B. Haas The Hospital for Special Surgery, New York, NY, USA I. Overview A. Deep-vein thrombosis (DVT) and pulmonary emboli (PEj remain one of the most serious and common complication following orthopaedic surgery II. Incidence of DVT and PE after total knee arthroplas A. D% T--No nroDhvkis 1. Venograihic’al& detected DVT: 65-88% 2. Proximal DVT: 3-20% B. DVT-l+?th prophylaxis 1. Aspirin: 41-73% 2. Warfarin: 24-69% 3. Pneumatic compression: lo-33% 17-45% 4. LMWH:
I55-175
III. Definition A. B.
of terms
Primary prophylaxis-preventing the occurrence of aDVT Secondary prophylaxis-preventing DVT from embolizing and preventing or identifying propagation
IV. Why is secondary prophylaxis important? Despite prophylaxis DVT occur Up to 50% of large proximal thrombi may embolize 3. Up to 24% of calf thrombi may propagate to the proximal veins. Calf thrombi is also associated with increased rates of symptomatic and asymtomatic PE ::
PE: (Haas et al., JBJS-B 1992) No Thrombi Calf Thrombi
Asymptotic PE ~~
Symptomatic FE: 0.2% 1.6%
V. Strategies for DVT prophylaxis A. B.
Use an effective primary prophylactic modalities in ALL patients Alternatives for post discharge management and secondary prophylaxis 1. Continue prophylaxis after discharge in ALL patients 2. Screen all patients: Treat or re-screen patients with DVT 3. Discontinue prophylaxis at discharge without screening
VI. What is best method to screen and detect deep vein thrombosis? A.
Clinical presentation-highly variable 1. Most DVT are asymptomatic 2. May be generalized including calf pain, leg swelling fever 3. Clinical exam unreliable for detection of DVT B. Venography-Contrast agent (ionic or non-ionic) is injected into the veins of the foot and under fluoroscopic monitoring X-ray are taken of the lower extremity. Advantages 1. Direct visualization of the thrombi (seen as a filling defect) 2. Sensitive for both proximal and distal DVT Disadvantage 1, Venous access must be obtained in the foot with risk of extravasation 2. Anaphylactoid reaction to contrast agent 3. Has been reported to precipitate thrombosis 4. Does not visualize deep femoral vein or internal iliac vein 5. Expensive C. B-mode Ultrasowzd-Several criteria used to detect thrombi including: l visualization of thrombi . inability to compress vein . percentage change in vein diameter during Valsalva maneuver Advantages 1. Non-invasive 2. No radiation exposure