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Use of interventional procedures for peripheral arterial occlusive disease in Ontario between 1991 and 1998: a population-based study

  • Mohammed Al-Omran
    Affiliations
    Institute for Clinical Evaluative Science, Toronto, Ont, Canada

    Clinical Epidemiology and Health Care Research Program, Toronto, Ont, Canada

    Department of Surgery, Toronto, Ont, Canada
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  • Jack V Tu
    Affiliations
    Institute for Clinical Evaluative Science, Toronto, Ont, Canada

    Clinical Epidemiology and Health Care Research Program, Toronto, Ont, Canada

    Department of Medicine, University of Toronto, Toronto, Ont, Canada

    Division of Internal Medicine, Toronto, Ont, Canada
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  • K.Wayne Johnston
    Affiliations
    Department of Surgery, Toronto, Ont, Canada

    Division of Vascular Surgery, Toronto General Hospital, Toronto, Ont, Canada
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  • Muhammad M Mamdani
    Affiliations
    Institute for Clinical Evaluative Science, Toronto, Ont, Canada

    Clinical Epidemiology and Health Care Research Program, Toronto, Ont, Canada
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  • Daryl S Kucey
    Correspondence
    Reprint requests: Daryl S. Kucey, MD, Sunnybrook Health Science Centre, 2075 Bayview Ave, H-185, Toronto, Ontario M4N 3M5, Canada.
    Affiliations
    Institute for Clinical Evaluative Science, Toronto, Ont, Canada

    Clinical Epidemiology and Health Care Research Program, Toronto, Ont, Canada

    Department of Surgery, Toronto, Ont, Canada

    Division of Vascular Surgery, Sunnybrook and Women’s College Health Science Centre, Toronto, Ont, Canada
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      Abstract

      Purpose

      Although peripheral arterial occlusive disease (PAOD) is a public health issue in the elderly population, limited population-based data are available on use of interventional procedures in Canada. We describe trends in use of interventional procedures to treat PAOD in Ontario over the past decade.

      Methods

      A retrospective population-based cohort study was conducted for fiscal years 1991 to 1998 with Ontario administrative databases to identify all arterial bypass surgeries, angioplasty procedures, and amputations performed.

      Results

      A total of 19,332 bypass operations, 16,334 angioplasty procedures, and 17,534 amputations were identified. Population-based rates showed that angioplasty use peaked at about 110 per 100,000 at age 65 to 74 years, arterial bypass surgery use peaked at 129 per 100,000 at age 75 to 84 years, and amputation use peaked at 138 per 100,000 at age 85 years or older. All types of interventional procedures to treat PAOD were performed more frequently in men than in women. Age-adjusted and sex-adjusted rate of arterial bypass surgery decreased significantly, from 77 to 61 per 100,000 population aged 45 years or older (P = .0002, linear regression analysis), whereas rate for PTA increased significantly, from 59 to 75 per 100,000 population aged 45 years or older (P = .0005). The overall major amputation rate declined slightly over the study period, influenced by the decreased rate in patients aged 85 years or older. The revascularization rate in patients aged 85 years or older increased (P = .055).

      Conclusion

      Reduced use of arterial bypass surgery and increased use of angioplasty procedures has occurred over the past decade and may reflect a change in the practice pattern of vascular surgeons in Ontario, who have become more conservative in treating localized disease and reserve surgical interventions for more severe forms of PAOD. The slight reduction in overall major amputation rate, driven by decreased rate in patients aged 85 years or older, may reflect a trend toward a more aggressive revascularization approach in this age group.
      Treatment of peripheral arterial occlusive disease (PAOD) is a major part of the workload of vascular surgeons. Management depends on stage and extent of disease (ie, intermittent claudication versus critical limb ischemia) and includes conservative management, percutanous transluminal angioplasty (PTA), arterial bypass surgery (ABS), and amputation. In general, PTA with or without stenting is preferred in patients with focal disease with satisfactory runoff vessels, and surgery is necessary for patients with diffuse disease and poor run-off vessels.
      TASC Working Group
      Managment of peripheral arterial disease (PAD). Trans Atlantic Inter-Society Consensus (TASC).
      Many patients with intermittent claudication have focal disease and can benefit from PTA; conversely, most patients with critical limb ischemia have diffuse disease that requires surgical intervention, ie, ABS, amputation, or both.
      Patients with PAOD in Ontario, Canada, are generally referred to vascular surgeons for evaluation. On the basis of stage and extent of disease, the vascular surgeon decides which type of treatment to offer the patient. It is unusual that a patient with PAOD is referred directly to an interventional radiologist for PTA without seeing a surgeon, but no doubt this occurs in some instances.
      Although PAOD is a major health problem, especially in the elderly population, little population-based research has been conducted regarding use of interventional procedures to treat PAOD in Canada. Thus the purpose of this study was to describe age-related and sex-related variations and temporal trends in use of these procedures in Ontario over the 8 years between 1991 and 1998.

      Methods

       Study design

      A retrospective population-based cohort study using Ontario administrative databases was conducted for fiscal years 1991 through 1998 (April 1 of the calendar year to March 31 of the following year).

       Identification of cases

      Case reports for ABS and amputation were obtained from the Canadian Institute for Health Information (CIHI) hospital discharge abstract database. The Ontario Health Insurance Plan (OHIP) database was used to obtain records of PTA procedures. (For details, see the Appendix [online only]).

       Data validation

      To validate coding for PAOD surgical procedures, 300 records from the CIHI database with ABS or amputation codes and a hospital code indicating Sunnybrook and Women’s College Health Science Centre, a major teaching hospital in Toronto, were randomly selected over the study period. These records were compared with corresponding patient charts from this hospital to assess level of agreement for procedure coding.

       Statistical analysis

      Patient age when the procedure was performed was divided into five groups, ie, 45 to 54 years, 55 to 64 years, 65 to 74 years, 75 to 84 years, and 85 years or older. The lower limit of 45 years was used because POAD interventional procedures are not likely to be performed in younger patients.
      • Simunovic M.
      • To T.
      • Johnston K.W.
      • Naylor C.D.
      Trends and variations in the use of vascular surgery in Ontario.
      The distribution of groups was based on decade of life increments. Age-specific rates for women, men, and both were calculated for each interventional procedure by using the Ontario age-stratified and sex-stratified population for the relevant year as the denominator.
      Overall rates for each procedure were calculated by using Ontario population aged 45 years or older for the relevant year as the denominator. Rates were directly standardized to the 1991 Ontario population aged 45 years and over by sex and the five age groups.
      Ontario population estimates for each year were obtained from Statistics Canada.

      Statistics Canada. Available at: http://www.statcan.ca. Accessed January 2001

      Confidence intervals for rate ratios were calculated according to the methods recommended by Rosner.
      • Rosner B.
      Changes in rate for procedures over the study period were assessed with least square linear regression with year as the independent variable and adjusted rate as the dependent variable. Results of regression analysis are presented as linear trend estimates with corresponding standard error. The linear trend estimate indicates the size and direction of average rate of change per year in the underlying incidence.
      Demographic differences between patients undergoing various procedures were assessed with the X2 test for categorical variables and the t test for continuous variables. All P values are two- tailed and considered significant at .05.
      Statistical analyses were performed with Statistical Applications Software, version 8 (SAS Institute, Cary, NC).

       Results

       Data validation

      Accuracy for recording ABS and amputation procedures in CIHI database records as compared with patient charts was 91.3% and 94%, respectively.

       Baseline characteristics

      Patient baseline characteristics are summarized in Table. During the study period 19,332 ABS were performed in Ontario; 22.7% were aorto-ilio-femoral bypass procedures, and 77.3 % were other peripheral bypass procedures. The operation-patient ratio for ABS was 1.22:1, for aorto-ilio-femoral bypass was 1.08:1, and for other peripheral bypass procedures was 1.24:1.
      Table ICharacteristics of patients who underwent interventional procedures on lower extremity secondary to PAOD in Ontario for fiscal years 1991-1998
      ABSPTA
      Fiscal years 1992-1998.
      ABS and PTA
      Fiscal years 1992-1998.
      (combined)
      Major amputation
      Number of procedures19,33216,34433,17110,844
      Number of patients15,82411,54825,1929034
      Mean age (y) (± SD)66.3 (11.9)65.6 (10.1)65.9 (11.3)72.1 (10.9)
      Sex (% F)37.640.238.938.4
      PAOD, peripheral arterial occlusive disease; ABS, arterial bypass surgery; PTA, percutaneous transluminal angioplasty.
      * Fiscal years 1992-1998.
      For fiscal years 1992 through 1998, 16,334 PTA procedures were performed in Ontario The procedure-patient ratio was 1.42:1.
      For fiscal years 1992 through 1998, 33,171 revascularization procedures (ABS and PTA combined) were performed in Ontario. Both bypass surgery and angioplasty were performed in 8.8% of patients.
      During the study period 17,534 amputations were performed in Ontario; 62% were major amputations, and 38% were minor amputations. The operation-patient ratio for any amputation was 1.35:1, for major amputation was 1.20:1, and for minor amputation was 1.20:1. Of major amputations, 54.6% were below-knee, 48% were above-knee, and 1.4% were through-ankle amputations. Surgery was bilateral in 9.2% of below-knee amputations and 8% of above-knee amputations.
      Although patients who underwent PTA were slightly younger than those who underwent ABS, patients who underwent amputation were older than those who underwent either angioplasty or bypass surgery (P < .0001).

       Age and gender differences

      Average annual age-adjusted and sex-adjusted rates and male-female age-adjusted rate ratios for POAD interventional procedures over the study period are presented in Table II.
      Table IIAverage age-adjusted rates
      Per 100,000 population 45 years of age or older.
      and rate ratios of interventional procedures for POAD in Ontario for fiscal years 1991-1998
      ProcedureAge-adjusted and sex-adjusted rateAge-adjusted rate for menAge-adjusted rate for womenRates ratio (men vs women)95% confidence interval
      ABS68.892.5047.901.931.79-2.11
      PTA
      Fiscal years 1992-1998.
      65.283.4049.101.701.58-1.86
      ABS & PTA
      Fiscal years 1992-1998.
      (combined)
      132.8174.396.21.811.68-1.98
      Major amputation38.3050.6027.501.841.66-2.07
      POAD, Peripheral arterial occlusive disease; ABS, arterial bypass surgery; PTA, percutaneous transluminal angioplasty.
      * Per 100,000 population 45 years of age or older.
      Fiscal years 1992-1998.
      Age-specific rate of POAD interventional procedures was similar for men and women, but was higher in men in all age groups. The rate was highest in men and women aged 65 to 74 years for PTA, 75 to 84 years for ABS, and 85 years or older for major amputation (Fig 1).
      Figure thumbnail GR1
      Fig 1Average annual rate of interventional procedures for peripheral occlusive arterial disease, by age and sex, in Ontario, for fiscal years 1991 through 1998. Note percutanous transluminal angioplasty rates for fiscal years 1992 through 1998.

       Temporal trends in rates of interventional procedures

      Temporal trends in age-adjusted and sex-adjusted rates of interventional procedures are presented in Fig 2. Age-adjusted and sex- adjusted rate of bypass surgery decreased significantly over the study period. This trend was influenced by significant reduction in age-adjusted rate for both genders (Table III). Although all age groups showed a declining rate of bypass surgery, there was an increasing trend of borderline significance (P = .06) in patients 85 years or older age (Table IV, A).
      Figure thumbnail GR2
      Fig 2Trends in age-adjusted and sex-adjusted rates of interventional procedures for peripheral occlusive arterial disease per 100,000 adults aged 45 years and older in Ontario, Canada. ABS, Arterial bypass surgery; PTA, percutanous transluminal angioplasty.
      Table IIILinear trend estimates for changes in rates of POAD interventional procedures in Ontario for fiscal years 1991-1998
      ProcedureLinear trend estimate
      Change in rate per 100,000 population per year.
      Standard errorP
      Least squares linear regression analysis.
      R2
      Least squares linear regression analysis.
      A. Age-adjusted and sex-adjusted rates (per 100,000 population aged 45 years and older)
      ABS−2.350.300.00020.91
      PTA
      Fiscal years 1992-1998.
      2.840.350.00050.93
      ABS and PTA
      Fiscal years 1992-1998.
      (combined)
      0.520.450.300.21
      Major amputation−0.450.180.050.52
      B. Age-adjusted rates for women (per 100,000 women aged 45 years and older)
      ABS−1.330.320.0060.74
      PTA
      Fiscal years 1992-1998.
      2.190.340.0010.89
      ABS and PTA
      Fiscal years 1992-1998.
      (combined)
      0.980.260.010.74
      Major amputation−0.340.200.140.32
      C. Age-adjusted rates for men (per 100,000 men aged 45 years and older)
      ABS−3.500.500.00040.89
      PTA
      Fiscal years 1992-1998.
      3.600.540.0010.90
      ABS and PTA
      Fiscal years 1992-1998.
      (combined)
      −0.010.780.990.00
      Major amputation−0.580.240.050.49
      POAD, Peripheral arterial occlusive disease; ABS, arterial bypass surgery; PTA, percutaneous transluminal angioplasty.
      * Change in rate per 100,000 population per year.
      Least squares linear regression analysis.
      Fiscal years 1992-1998.
      Table IVLinear trends estimates for changes in age-specific rates of PAOD interventional procedures in Ontario for fiscal years 1991-1998
      Age group (y)Linear trend estimate
      Change in rate per 100,000 population per year.
      Standard errorP
      Least squares linear regression analysis.
      R2
      Least squares linear regression analysis.
      A. ABS age-specific rates (per 100,000)
      45-54−1.370.240.0010.84
      55-64−3.340.300.00010.95
      65-74−3.100.900.0140.66
      75-84−2.311.150.090.40
      ≥852.100.890.060.48
      B. PTA
      Fiscal years 1992-1998.
      age-specific rates (per 100,000)
      45-540.700.290.060.55
      55-641.940.630.030.65
      65-745.390.780.0010.90
      75-846.720.920.0010.91
      ≥853.011.330.070.51
      C. ABS and PTA age-specific rates (per 100,000)
      45-54−0.410.550.490.10
      55-64−1.600.930.150.37
      65-741.961.160.150.36
      75-844.821.850.050.58
      ≥855.662.270.0550.50
      D. Major amputation age-specific rates (per 100,000)
      45-54−0.100.110.390.26
      55-64−0.050.280.280.38
      65-74−0.250.440.590.10
      75-84−1.450.890.150.49
      ≥85−4.682.030.060.52
      PAOD, Peripheral arterial occlusive disease; ABS, arterial bypass surgery; PTA, percutaneous transluminal angioplasty.
      * Change in rate per 100,000 population per year.
      Least squares linear regression analysis.
      Fiscal years 1992-1998.
      On the other hand, age-adjusted and sex adjusted rates of PTA increased significantly over the study period. This increase reflected significant increases observed in both sexes (Table III). All age groups showed a significant increase in age-specific rate over the study period (Table IV, B). The overall age-adjusted and sex-adjusted rates for revascularization procedures (bypass surgery and angioplasty combined) was stable over the study period (Table III). Younger age groups showed a declining rate of revascularization procedures, whereas the older age groups showed an increasing trend (Table IV, C).
      Age-adjusted and sex-adjusted rate of major amputation declined slightly over the study period in both men and women, but failed to reach significance in men (Table III). Although all age groups showed slight but not significant reduction in rate of major amputation, the rate was reduced on average by 4.68 procedures per 100,000 per year in the group 85 years or older (R2= 0.52; P = .06; Table IV, D).

       Discussion

      This study provides a comparative global picture of the practice of vascular surgery in Ontario over the past decade. As in previous reports,
      • Simunovic M.
      • To T.
      • Johnston K.W.
      • Naylor C.D.
      Trends and variations in the use of vascular surgery in Ontario.
      ,
      • Tunis S.R.
      • Bass E.B.
      • Klag M.J.
      • Steinberg E.P.
      Variation in utilization of procedures for treatment of peripheral arterial disease a look at patient characteristics.
      ,
      • Hallett Jr, J.W.
      • Byrne J.
      • Gayari M.M.
      • Ilstrup D.M.
      • Jacobsen S.J.
      • Gray D.T.
      Impact of arterial surgery and balloon angioplasty on amputation a population-based study of 1155 procedures between 1973 and 1992.
      ,
      • Pell J.P.
      • Fowkes F.G.
      • Ruckley C.V.
      • Clarke J.
      • Kendrick S.
      • Boyd J.H.
      Declining incidence of amputation for arterial disease in Scotland.
      all types of interventional procedures for PAOD were performed more frequently in men than in women. This is explained by the higher prevalence of PAOD in men than in women.
      TASC Working Group
      Managment of peripheral arterial disease (PAD). Trans Atlantic Inter-Society Consensus (TASC).
      ,
      • Reunanen A.
      • Takkunen H.
      • Aromaa A.
      Prevalence of intermittent claudication and its effect on mortality.
      ,
      • Criqui M.H.
      • Fronek A.
      • Barrett-Conner E.
      • Klauber M.R.
      • Gabriel S.
      • Goodman D.
      The prevalence of peripheral arterial disease in a defined population.
      ,
      • Kannel W.B.
      • McGee D.L.
      Update on some epidemiologic features of intermittent claudication. The Framingham Study.
      ,
      • Widmer L.K.
      • Biland L.
      • Delley A.
      • Da Silva A.
      [The importance of peripheral-arterial occlusive diseases in medical practice conclusions from the Basel study].
      Rate of use of interventional procedures increases with age. Average annual rate for use of PTA peaked in patients 65 to 74 years of age, compared with 75 to 84 years of age for ABS and 85 years of age or older for amputation. Similar findings were reported by Tunis et al.
      • Tunis S.R.
      • Bass E.B.
      • Klag M.J.
      • Steinberg E.P.
      Variation in utilization of procedures for treatment of peripheral arterial disease a look at patient characteristics.
      This finding may be explained by the age-related progression of PAOD.
      TASC Working Group
      Managment of peripheral arterial disease (PAD). Trans Atlantic Inter-Society Consensus (TASC).
      Younger patients are more likely to have milder forms of PAOD that may require only PTA, whereas older patients may have more severe forms of the disease that require bypass surgery or amputation.
      The overall rate of ABS for PAOD in Ontario decreased during the study period, continuing the trend reported earlier.
      • Simunovic M.
      • To T.
      • Johnston K.W.
      • Naylor C.D.
      Trends and variations in the use of vascular surgery in Ontario.
      This pattern could represent a change in either incidence of PAOD or the practice of surgery, or perhaps both. Although no data are available on incidence of PAOD in Canada, it is unlikely that reduction in incidence of PAOD explains the reduction in ABS rate. This finding suggests that Ontario vascular surgeons may have become more conservative in treating localized disease and may reserve surgical intervention for more severe forms of PAOD. This hypothesis is supported by the observed increase in rate of angioplasty while the overall rate of revascularization procedures (PBS and PTA) remained stable over the same period. This may indicate a “substitution effect” of angioplasty for bypass surgery.
      The overall major amputation rate declined slightly over the study period, driven by decreased rate in patients aged 85 years or older. This reduction might be explained by the increased rate of ABS in this age group, which consequently may have led to reduction in secondary amputation rate.
      Although many population-based studies from the United States, Europe and Australia have examined the rates of interventional procedures,
      • Hallett Jr, J.W.
      • Byrne J.
      • Gayari M.M.
      • Ilstrup D.M.
      • Jacobsen S.J.
      • Gray D.T.
      Impact of arterial surgery and balloon angioplasty on amputation a population-based study of 1155 procedures between 1973 and 1992.
      ,
      • Pell J.P.
      • Fowkes F.G.
      • Ruckley C.V.
      • Clarke J.
      • Kendrick S.
      • Boyd J.H.
      Declining incidence of amputation for arterial disease in Scotland.
      ,
      • Tunis S.R.
      • Bass E.B.
      • Steinberg E.P.
      The use of angioplasty, bypass surgery, and amputation in the management of peripheral vascular disease.
      ,
      • Sayers R.D.
      • Thompson M.M.
      • Varty K.
      • Jagger C.
      • Bell P.R.
      Changing trends in the management of lower-limb ischaemia a 17-year review.
      ,
      • Ebskov L.B.
      • Schroeder T.V.
      • Holstein P.E.
      Epidemiology of leg amputation the influence of vascular surgery.
      ,
      • Mattes E.
      • Norman P.E.
      • Jamrozik K.
      Falling incidence of amputations for peripheral occlusive arterial disease in Western Australia between 1980 and 1992.
      ,
      • Feinglass J.
      • Brown J.L.
      • LoSusso A.
      • Sohn M.W.
      • Manheim L.M.
      • Shah S.J.
      • et al.
      Rates of lower-extremity amputation and arterial reconstruction in the United States, 1979 to 1996.
      comparison of these findings with ours is difficult. Previous studies included the population younger than 45 years of age in the analysis and therefore in the denominator for rate calculation. This may be not appropriate, because interventional procedures for POAD are unlikely to be performed in persons younger than 45 years.
      • Simunovic M.
      • To T.
      • Johnston K.W.
      • Naylor C.D.
      Trends and variations in the use of vascular surgery in Ontario.
      Other studies have examined temporal trends in rates of interventional procedures for POAD (Table V).
      • Simunovic M.
      • To T.
      • Johnston K.W.
      • Naylor C.D.
      Trends and variations in the use of vascular surgery in Ontario.
      ,
      • Hallett Jr, J.W.
      • Byrne J.
      • Gayari M.M.
      • Ilstrup D.M.
      • Jacobsen S.J.
      • Gray D.T.
      Impact of arterial surgery and balloon angioplasty on amputation a population-based study of 1155 procedures between 1973 and 1992.
      ,
      • Pell J.P.
      • Fowkes F.G.
      • Ruckley C.V.
      • Clarke J.
      • Kendrick S.
      • Boyd J.H.
      Declining incidence of amputation for arterial disease in Scotland.
      ,
      • Tunis S.R.
      • Bass E.B.
      • Steinberg E.P.
      The use of angioplasty, bypass surgery, and amputation in the management of peripheral vascular disease.
      ,
      • Sayers R.D.
      • Thompson M.M.
      • Varty K.
      • Jagger C.
      • Bell P.R.
      Changing trends in the management of lower-limb ischaemia a 17-year review.
      ,
      • Ebskov L.B.
      • Schroeder T.V.
      • Holstein P.E.
      Epidemiology of leg amputation the influence of vascular surgery.
      ,
      • Mattes E.
      • Norman P.E.
      • Jamrozik K.
      Falling incidence of amputations for peripheral occlusive arterial disease in Western Australia between 1980 and 1992.
      ,
      • Feinglass J.
      • Brown J.L.
      • LoSusso A.
      • Sohn M.W.
      • Manheim L.M.
      • Shah S.J.
      • et al.
      Rates of lower-extremity amputation and arterial reconstruction in the United States, 1979 to 1996.
      ,
      Lower extremity arterial occlusive disease.
      Table VPeripheral occlusive arterial disease interventional procedure trends comparison with previously published population-based studies
      StudyDurationSettingArterial bypass surgeryPercutanous transluminal angioplastyMajor amputation
      Tunis et al,
      • Tunis S.R.
      • Bass E.B.
      • Steinberg E.P.
      The use of angioplasty, bypass surgery, and amputation in the management of peripheral vascular disease.
      1991
      1979-1989MarylandIncreased (17,633)Increased (2,805)No change (10,619)
      Sayers et al,
      • Sayers R.D.
      • Thompson M.M.
      • Varty K.
      • Jagger C.
      • Bell P.R.
      Changing trends in the management of lower-limb ischaemia a 17-year review.
      1993
      1974-1990Leicester, EnglandIncreased (1,095)Increased (677)No change (1,158)
      Ebskov et al,
      • Ebskov L.B.
      • Schroeder T.V.
      • Holstein P.E.
      Epidemiology of leg amputation the influence of vascular surgery.
      1994
      1983-1990DenmarkIncreasedIncreasedDecreased
      Pell et al,
      • Pell J.P.
      • Fowkes F.G.
      • Ruckley C.V.
      • Clarke J.
      • Kendrick S.
      • Boyd J.H.
      Declining incidence of amputation for arterial disease in Scotland.
      1994
      1981-1990ScotlandIncreasedNADecreased
      Simunovic et al,
      • Simunovic M.
      • To T.
      • Johnston K.W.
      • Naylor C.D.
      Trends and variations in the use of vascular surgery in Ontario.
      1996
      1981-1991Ontario, CanadaDecreased (30,751)NANA
      Mattes et al,
      • Mattes E.
      • Norman P.E.
      • Jamrozik K.
      Falling incidence of amputations for peripheral occlusive arterial disease in Western Australia between 1980 and 1992.
      1997
      1980-1992AustraliaIncreased (2,664)Increased (2,184)Decreased (1,850)
      Hallett et al,
      • Hallett Jr, J.W.
      • Byrne J.
      • Gayari M.M.
      • Ilstrup D.M.
      • Jacobsen S.J.
      • Gray D.T.
      Impact of arterial surgery and balloon angioplasty on amputation a population-based study of 1155 procedures between 1973 and 1992.
      1997
      1973-1992MinnesotaIncreased (733)Increased (59)Decreased (288)
      Feinglass et al,
      • Feinglass J.
      • Brown J.L.
      • LoSusso A.
      • Sohn M.W.
      • Manheim L.M.
      • Shah S.J.
      • et al.
      Rates of lower-extremity amputation and arterial reconstruction in the United States, 1979 to 1996.
      1999
      1979-1996United States, nationwideIncreasedIncreasedNo change
      Despite major amputation rate decreased between 1983 and 1984, and 1991 and 1992, but by 1995-1996 the rate of major amputation had increased 10.6% since 1979-1980. Overall trend showed no change.
      Dartmouth atlas,
      Lower extremity arterial occlusive disease.
      2000
      1993-1996US Medicare populationIncreasedIncreasedIncreased
      Current study1991-1998Ontario, CanadaDecreased (19,332)Increased (16,344)Decreased slightly (10,844)
      Note: Numbers in parentheses are numbers of procedures during the study period, if they were mentioned.
      NA, Data not available.
      * Despite major amputation rate decreased between 1983 and 1984, and 1991 and 1992, but by 1995-1996 the rate of major amputation had increased 10.6% since 1979-1980. Overall trend showed no change.
      Unlike other regions, the Ontario bypass surgery rate has continued to decrease, from the 1980s, as shown by Simunovic et al,
      • Simunovic M.
      • To T.
      • Johnston K.W.
      • Naylor C.D.
      Trends and variations in the use of vascular surgery in Ontario.
      to the late 1990s, as shown by the present study. On the other hand, the rate of PTA during the same period increased in Ontario, as in other regions. The major amputation rate decreased slightly in Ontario, as well as in other studied areas,
      • Hallett Jr, J.W.
      • Byrne J.
      • Gayari M.M.
      • Ilstrup D.M.
      • Jacobsen S.J.
      • Gray D.T.
      Impact of arterial surgery and balloon angioplasty on amputation a population-based study of 1155 procedures between 1973 and 1992.
      ,
      • Pell J.P.
      • Fowkes F.G.
      • Ruckley C.V.
      • Clarke J.
      • Kendrick S.
      • Boyd J.H.
      Declining incidence of amputation for arterial disease in Scotland.
      ,
      • Ebskov L.B.
      • Schroeder T.V.
      • Holstein P.E.
      Epidemiology of leg amputation the influence of vascular surgery.
      ,
      • Mattes E.
      • Norman P.E.
      • Jamrozik K.
      Falling incidence of amputations for peripheral occlusive arterial disease in Western Australia between 1980 and 1992.
      but in the same period it did not change in Maryland or in the United Kingdom.
      • Tunis S.R.
      • Bass E.B.
      • Steinberg E.P.
      The use of angioplasty, bypass surgery, and amputation in the management of peripheral vascular disease.
      ,
      • Sayers R.D.
      • Thompson M.M.
      • Varty K.
      • Jagger C.
      • Bell P.R.
      Changing trends in the management of lower-limb ischaemia a 17-year review.
      Furthermore, the major amputation rate increased in the US Medicare population.
      Lower extremity arterial occlusive disease.
      These variations may be explained by (1) variations in surgical practice between regions; (2) severity of underlying disease in patients receiving treatment; (3) variations in the population studied; for example, in the study reported in the Dartmouth Atlas,
      Lower extremity arterial occlusive disease.
      only Medicare beneficiaries 65 years or older were studied; (4) most studies were conducted in the 1980s, whereas the present study was conducted in the 1990s, and vascular surgeons may have become more familiar with the role of PTA and precise indications for surgery; (5) variations in incidence and prevalence of POAD between regions; (6) supply of health care resources; and (7) patient preference.
      In evaluation of our results, several potential limitations related to our use of administrative databases should be considered. First, the service code J025, which was used to identify PTA cases, is not specific for lower extremity angioplasty; it was also used for renal angioplasty until 1994, and is still used for upper extremity and carotid PTA. Although an effort was made to decrease the number of renal and carotid angioplasty cases by excluding records with diagnosis codes indicating disease other than PAOD, only 73 of 17,879 records were excluded. Most physicians do not record the diagnosis on the claims statement, because in most cases a diagnosis is not required for payment.
      • Williams J.I.
      • Young W.
      However, an expert consultant suggested that more than 85% of included cases are indeed PAOD (Dr Stuart Bell, Department of Diagnostic Imaging, University of Toronto, personal communication, 2002).
      Second, accuracy of coding diagnoses and procedures in the databases may be suspect. Although the percentage of matched CIHI database records with patient charts for bypass surgery and amputation procedure codes is high (93%), validation was performed only in a single teaching hospital in Toronto, which may not represent the experience of the entire province. Furthermore, the level of agreement for PTA coding between the OHIP database records and actual physician claims records was not assessed.
      Finally, rates of procedures were estimated at the population level rather than the patient level, and therefore may reflect multiple procedures in the same patient. Furthermore, attributing changes in rates of interventional procedures over the study period to the surgical practice pattern of vascular surgeons may be biased, because incidence and prevalence of underlying disease are not known.
      In summary, we found that use of interventional procedures for PAOD was more common in men and older age groups, which is consistent with the age-related progression of disease and the higher prevalence of disease in men than in women. Furthermore, reduction in the use of bypass surgery and increased use of angioplasty, while overall revascularization rate remained stable, suggests substitution of angioplasty for bypass surgery. This likely reflects a change in the practice pattern of vascular surgeons in Ontario, who may have become more conservative in treating localized disease and reserve surgical intervention for more severe forms of POAD. The slight reduction in overall major amputation rate, driven by decreased rate in patients aged 85 years or older, may reflect a trend toward more aggressive revascularization treatment in this age group.

      Appendix, Online only.

       Data sources

      This study was conducted at the Institute for Clinical Evaluative Science (ICES) in Ontario. Case records for arterial bypass surgery and amputation were obtained from the Canadian Institute for Health Information (CIHI) hospital discharge abstract database. This database records discharges from all Ontario acute-care hospitals, including day surgeries, and contains information on patient demographics, diagnosis, and procedures. The diagnosis codes are based on the International classification of disease, 9th revision (ICD-9),
      US National Center for Health Statistics
      and treatment codes are based on the Canadian classification of diagnostic, therapeutic and surgical procedures (CCP).
      Since not all angioplasty procedures were performed as in-patient procedures, the CIHI database could not provide full information about PTA. Therefore the Ontario Health Insurance Plan (OHIP) database was used to determine PTA procedures. This database records claims paid for health care providers by the Ontario Ministry of Health, which is the sole payer for health care in Ontario. The OHIP diagnosis and procedure codes are based on the Minister of Health fee service and diagnosis codes.
      Ontario Ministry of Health
      The OHIP database lacks demographic information on patients; therefore it was linked to the Ontario Registered Persons Data Base (RPDB), which records demographic information that describes persons who are or were entitled to medical services under OHIP. Each patient in these databases (CIHI, OHIP, RPDB) has the same unique encrypted identifier.

       Identification of cases

       Arterial bypass surgery procedures

      Using the CIHI database, we obtained discharge abstracts for all patients 45 years of age or older who were discharged between April 1, 1991, and March 31, 1999, with a procedure code (CCP 51.25, 51.29) for lower extremity arterial bypass surgery (ABS). Code CCP 51.25 was considered indicative of aorto-ilio-femoral bypass procedures, and CCP 51.29 was considered indicative of other peripheral bypass procedures. To ensure that only procedures for PAOD were included, records with a primary diagnosis code indicating abdominal aortic aneurysm (ICD-9 441.3-441.7), iliac artery aneurysm (ICD-9 442.0, 442.2), or lower extremity artery aneurysm (ICD-9 Code 442.3) were excluded. Duplicate records, defined as a record with similar unique encrypted identifier, admission date, procedure, and diagnosis codes, were excluded. Records with missing unique encrypted identifier also were excluded.

       Amputation procedures

      Using the CIHI database, we obtained discharge abstracts for all patients 45 years of age or older who were discharged between April 1, 1991, and March 31, 1999, with a procedure code (CCP 96.11-96.15) for lower extremity amputation. Records with toe (CCP 96.11) or through-foot (CCP 96.12) amputation were defined as minor amputation, and records with ankle (CCP 96.13), below-knee (CCP 96.14), or above-knee (CCP 96.15) amputation were defined as major amputation. To ensure that only amputations because of PAOD were included, records with a primary diagnosis code indicating trauma (ICD-9 800-900), congenital anamoly (ICD-9 740-759), tumor (ICD-9 170, 171, 213), arterial injury (ICD-9 901-904), or burn (ICD-9 940-950) were excluded. Duplicate records and abstracts with missing unique encrypted identifier were excluded.

       Percutanous transluminal angioplasty procedures

      OHIP claim records at ICES for fiscal year 1991 are not complete; therefore the decision was made to include only records for fiscal years 1992 through 1998. %Claims for all patients between April 1, 1992, and March 31, 1999, with a service code for lower extremity percutaneous transluminal angioplasty (PTA; J025) were obtained from the OHIP database. Service code J025 is not specific for lower extremity angioplasty; it was also used for renal angioplasty until 1994 and is still in use for upper extremity and carotid PTA.
      Although not all physicians record the diagnosis in OHIP claims, records with diagnosis codes indicating renal vascular anomalies (CCP 593.8), hypertensive renal disease (CCP 403), renal failure (CCP 584, 584), transient ischemic attack (CCP 435), or chronic arteriosclerotic cerebrovascular disease (CCP 437) were excluded in an effort to decrease the number of renal and carotid angioplasty cases. To obtain demographic features of patients who underwent PTA, claim records were linked to the RPDB with the unique encrypted identifier. Any record for patients younger than 45 years was excluded. Duplicate records, defined as a record with similar unique encrypted identifier, service date, procedure, and diagnosis codes, were excluded. Records with missing unique encrypted identifier also were excluded.

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