The Evolution of Amputation in the Province of Quebec

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REvIEw

The Evolution of Amputation in the Province of Quebec

Diana Dawes MSc, Sameena Iqbal MD, Oren K. Steinmetz MD, Nancy Mayo PhD McGill University, Montreal, Quebec, Canada

ABSTRACT OBJECTIvE: Lower-extremity amputation rate is often used as

an indicator of the quality of diabetes care. This study provides a long-term perspective on amputation in the Quebec population, estimating changes over time in rates of vascular amputation and comorbidity profile. METhODS: A population-based admission-to-discharge

cohort study was conducted using hospital discharge data. The population consisted of all Quebec residents having an amputation from January 1, 1996, to December 31, 2004. The reason for amputation was defined by diagnostic code; the level of amputation was identified by treatment code; and the proportion of people with specific comorbidities was calculated for each year. Age- and sex-specific rates of amputation were calculated. RESULTS: A total of 10 834 people had 15 992 amputations.

Of these people, 79% had vascular disease. Within this population, hypertension has increased by 27.2% (95% CI 22.9–31.6), renal disease by 14.9% (95% CI 11.1–18.7) and ischemic heart disease by 20.4% (95% CI 16.3–24.4). Length of hospital stay did not change over time; the median length of stay was 20 days (IQR: 8.5, 40, 658). Women having foot amputations, people having multiple amputations or people with a high Charlson index score were more likely to stay in hospital for more than 28 days. A linear decrease in the rate of vascular and diabetic amputations was observed for both men and women, with the greatest decrease being 8.1% (95% CI 5.8–10.4) among males with vascular disease.

INTERpRETATION: Despite the decline in sex-specific, agestandardized rates of amputation, there was no decrease in the number of amputations being performed; this may reflect the increased prevalence of diabetes and standard of care being given. The implication for the changing profile of people having amputations are great: for example, post-amputation care needs to address the multiple comorbidities. KEywORDS: amputation, comorbidity, diabetes.

RÉSUMÉ OBJECTIF : Le taux d’amputation des membres inférieurs est

souvent utilisé comme indicateur de la qualité des soins du diabète. La présente étude donne une perspective à long terme des amputations dans la population québécoise en estimant les changements du taux d’amputation pour cause vasculaire et du profil des troubles comorbides. MÉThODES : Une étude de cohortes populationnelle cou-

vrant la durée de l’hospitalisation des sujets a été menée à partir des données sur les congés des hôpitaux. Les sujets de l’étude étaient tous les résidants du Québec qui avaient subi une amputation entre le 1er janvier 1996 et le 31 décembre 2004. Le motif de l’amputation était défini en fonction du code du diagnostic, le niveau d’amputation était défini en fonction du code du traitement et la proportion des personnes présentant des troubles comorbides donnés était calculée chaque année. Les taux d’amputation ont été calculés en fonction de l’âge et du sexe.

Address for correspondence: Diana Dawes, Clinical Epidemiology R4.34 McGill University Health Centre, Royal Victoria Hospital 687, avenue des Pins Ouest, Montreal, Quebec, Canada H3A 1A1 Telephone: (514) 934-1934 ext. 36912/36906, Fax: (514) 843-1493, E-mail: [email protected]

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AMPUtAtION IN QUebeC

RÉSULTATS : Au total, 10 834 personnes ont subi 15 992 amputations. Parmi ces personnes, 79 % présentaient une maladie vasculaire. Dans cette population, l’incidence de l’hypertension a augmenté de 27,2 % (IC de 95 % : 22,931,6), celle de la néphropathie, de 14,9 % (IC de 95 % : 11,1-18,7) et celle de la cardiopathie ischémique, de 20,4 % (IC de 95 % : 16,3-24,4). La durée du séjour à l’hôpital n’a pas changé avec le temps; la durée médiane du séjour a été de 20 jours (intervalle interquartile : 8,5, 40, 658). Les femmes ayant subi une amputation de pied, les personnes ayant subi plus d’une amputation et les personnes dont l’indice de Charlson était élevé étaient plus susceptibles de passer plus de 28 jours à l’hôpital. Il y a eu une réduction linéaire du taux d’amputation pour cause vasculaire et pour diabète tant chez les hommes que chez les femmes, la baisse la plus marquée, soit de 8,13 % (IC de 95 % : 5,82-10,4), ayant été observée chez les hommes présentant une maladie vasculaire. INTERpRÉTATION : Malgré la baisse du taux d’amputation dans

les deux sexes, standardisé pour l’âge, il n’y a pas eu de baisse du nombre d’amputations effectuées, ce qui pourrait être le reflet de l’augmentation de la prévalence du diabète et des soins donnés. Les répercussions en ce qui a trait au changement du profil des patients subissant une amputation sont énormes : par exemple, les soins prodigués après une amputation doivent tenir compte de plusieurs troubles comorbides. MOTS CLÉS : diabète, amputation, troubles comorbides

INTRODUCTION Diabetes mellitus is the leading cause of nontraumatic lowerlimb amputation (1), a costly and disabling procedure. The incidence of vascular amputation varies widely, not only between regions and populations, but also over time (2,3). Amputation results in physical and emotional changes that affect quality of life (4). It is also costly to the patient and the health system: the annual cost of amputation due to diabetes in the US is estimated to exceed US$1.6 billion (5). Lower-extremity amputation rate is often used as an indicator of the quality of diabetes care (6-9), since elevated blood glucose levels compromise the vascular bed, leaving peripheral organs at risk. In a 2003 trial of outcomes associated with team care for persons with diabetes, microvascular disease was an endpoint (10). With the aging population and increasing incidence of diabetes, the impact of diabetesrelated complications (including lower-extremity amputation) on healthcare resources will become substantial. One of the objectives of the US Healthy People 2010 Information Access Project (11) is to reduce the rate of lower-extremity amputations in persons with diabetes by 1.8 per 1000 persons with diabetes per year. Their rationale for aiming to reduce the amputation rate is as follows:

If hyperglycaemia or other serious comorbid conditions, such as high blood pressure or elevated blood lipids, are present in certain racial and ethnic groups, a greater diabetes-related disease burden will occur. Many other factors could be involved, including genetics and excess weight. Greater seriousness of diabetes can be determined by comparing, for example, death or amputation rates for specific racial and ethnic diabetic groups with those rates in the general diabetic population (11). Estimating true incidence requires a population-based approach; however, the accuracy of many current reports is limited, as they are confined to small geographic regions or restricted by age, ethnic group, level of amputation or time. A 2003 review (2) of studies on the rate of diabetic amputation at centres around the world demonstrated a high degree of variability, with the US having very high rates (40–170 per 10 000 people with diabetes) and Scandinavian countries having very low rates (<5 per 10 000 people with diabetes). A 2008 Swedish study demonstrated a fall in major diabetes-related amputations between 1982–1985 and 1998–2001, from 16.0 to 6.8 per 100 000 population, but at the same time an increase in minor diabetes-related amputations: 4.7 to 6.5 per 100 000 population (9). Onethird of this decrease in major amputation rate is attributable to an increase in the minor amputation rate; however, the reasons for this are unclear. The only Canadian study — examining geographical differences in Ontario based on 1987–1988 amputation data — derived a synthetic estimate of the number of people with diabetes in Ontario based on US diabetes rates (12) and reports a rate of 40 per 10 000 people with diabetes. This review also demonstrated that the rate of amputation increased dramatically with age (<20 per 10 000 for people under 44 years of age, up to 86 per 10 000 for men over 86 years of age) and was higher among non-white races and men (50 men vs. 36 women per 10 000). This study was unable to examine changes in amputation rates over time, however. The Canadian Diabetes Association (CDA) continues to use US data to estimate Canadian diabetes rates due to a lack of Canadian research in this area; we hope to fill some of this gap. This study seeks to provide a long-term perspective on the evolution of amputation in the Canadian population from Quebec. Hospitalization records covering a 9-year period were reviewed to estimate changes over time in rates of vascular amputation, comorbidity profile and case fatality rates.

METhODS A population-based admission-to-discharge cohort study was conducted using the province of Quebec’s hospital discharge database (MedEcho). In Quebec, all separations from publicly funded hospitals are recorded for the purposes of administration. The discharge record includes an anonymous, unique patient identifier; demographic information; CANADIAN JOURNAL OF DIABETES. 2010;34(1):58-66.

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type of admission; all diagnoses contributing to the length of stay, including co-morbidities; all procedures carried out while in hospital; complications; duration of stay; and place of discharge. At this time, diagnoses were classified according to the 9th revision of the International Classification of Diseases (ICD-9), and procedures were coded according to the Canadian Classification of Diagnostic, Therapeutic and Surgical Procedures (CCP). The study population included all Quebec residents discharged from a Quebec acute-care hospital between January 1, 1996, and December 31, 2004, with a procedure code indicating amputation (CCP 96:11 to 96:19). Reason for amputation was defined by diagnostic code as used by others in similar studies (13): diabetes-related (ICD-9 250 and 362), vascular (ICD-9 440-4, 414, 459, 451, 412, 403, 437), trauma (ICD-9 905-6, 908, 928, 820-8, 808, 895-7, 905, 928-9), cancer (ICD-9 170-3), congenital (ICD-9 747, 755-6). If there was more than 1 possible reason for amputation (e.g. cancer and diabetes), or none of the above codes, 2 investigators (DD and SI) independently looked at all diagnostic and treatment codes for the individual and came to agreement as to which category best fitted that individual’s diagnostic profile. Agreement was reached in 100% of cases. Only the vascular patients (vascular disease with and without diabetes) were included in this study, as people having amputations due to other causes are very different from people having amputation for vascular disease (14). Level of amputation was classified using the same criteria as Lawee and Csima in their study on amputations in Ontario (12): amputation and disarticulation of toe(s), foot, ankle (CCP 96.11, 96.12, 96.13); transtibial amputation (CCP 96.14); knee disarticulation and transfemoral amputation (CCP 96.15); disarticulation of hip, abdominopelvic, unspecified lower-limb amputation (CCP 96.16, 96.17, 96.19). Comorbidities were identified for the vascular patients from the MedEcho file. As each record on this database included an anonymous unique identifier, a longitudinal amputation profile was created for each individual. The Charlson index covers 19 categories of disease; a score ≥2 is considered severe (15).

Statistical analysis Descriptive statistics were carried out to characterize the population at each year of study. Age- and sex-specific rates of toe/metatarsal/ankle, transtibial and knee disarticulation/ transfemoral amputation were calculated for 5 age groups (18–54; 55–64; 65–74; 75–84; and over 84 years), and for each of the 9 years of the study. In-hospital mortality rates were calculated as the proportion of people who died before hospital discharge. Hospital length of stay and the proportion of people going to

rehabilitation, home, long-term care, transferred hospital or deceased by level of amputation was calculated for each year. The effects of sex, age, comorbidity, number of amputations and discharge destination on the probability of staying in hospital more than 28 days were estimated using logistic regression. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for all variables in a multivariate model. The 28-day criterion was used, as events within this period for hospitalized patients were considered to be part of the same episode of care and were coded as complications. The sex-specific, age-standardized rates of amputation were calculated using the sizes of the Quebec population of men and women for the above age groups as estimated from the Canadian census for these years. Direct standardization was used to estimate, for men and women separately, an overall rate of vascular (with diabetes) amputation and vascular (without diabetes) amputation for each year. For this calculation, the distribution of the 1991 Quebec population ≥18 years of age served as the standard. Poisson regression was used to estimate the extent to which rates of vascular amputation with and without diabetes changed over time. The numerator for the rates was the number of amputations in each age–sex stratum; the denominator was the size of the population in each age–sex stratum. The natural logarithm of each rate was modelled as a function of time. The modelling variables were 1) time used as a continuous variable and coded from 0 (1996) to 8 (2004); 2) time*time coded as (time-mean time) (16), where mean time is 4; and 3) a dummy variable for each age group, with 65–74 years as the reference age group. To test whether the decline in rates of amputation differed for men and women, we used a Poisson regression model with sex as a covariate and tested the interaction between sex and time. This analysis was part of a larger study on amputations in Quebec, which had approval from the local hospital research ethics board (SDR-07-013).

RESULTS The population of Quebec was 5 891 323 in 1996 and had increased to 6 211 159 by 2004. From January 1, 1996, to December 31, 2004, a total of 10 834 people had 15 992 amputations in Quebec hospitals (Table 1). More than 50% of the population had vascular disease with diabetes, and 28% had vascular disease without diabetes. Of all the vascular amputations (with or without diabetes) 7300 (55%) were at the level of the toe, metatarsus or ankle; 3209 (24%) were transtibial; 2743 (20%) were knee disarticulation or transfemoral; and 114 (1%) were unclassified or at higher levels (hip/pelvic). The numbers of people having vascular amputations, amputations performed, median ages and comorbidities are categorized by the 3 main surgical levels and presented

AMPUtAtION IN QUebeC

Table 1. Distribution of aetiology and level of amputations in Quebec from January 1, 1996, to December 31, 2004

People, n (%)

Disease Diabetes*

Amputations, n

Toe/ metatarsus/ ankle, n

Transfemoral/ knee disarticulation, n

Transtibial, n

Unclassified or pelvic, n

419 (4)

495

426

48

15

6

Vascular disease

2992 (28)

3934

1639

939

1297

59

Diabetes with vascular disease

5472 (51)

9432

5661

2270

1446

55

Trauma

384 (4)

432

271

104

51

6

Cancer

205 (2)

220

103

24

44

49

Congenital

48 (<1)

53

51

1

1

0

1314 (12)

1426

1224

81

81

40

10 834 (100)

15 992

9375

3467

2935

215

†

Unclassifiable Total

*Diabetes without vascular disease; †Vascular disease without diabetes

Table 2. Distribution of age and comorbidities for the population with vascular amputations* for 3 sample years Toe/metatarsus/ankle

Transtibial

Transfemoral/ knee disarticulation

1996

2000

2004

1996

2000

2004

1996

2000

2004

People, n

600

713

720

307

354

327

290

305

274

Amputations, n

750

866

885

318

367

338

301

317

287

Males, %

74

74

73

71

71

74

60

62

65

Median age,† years

68

69

69

68

72

71

72

74

74

age 18–54, %, years

16

19

17

15

11

14

6

7

6

age 55–64, %, years

22

19

22

23

19

19

16

16

16

age 65–74, %, years

34

31

29

37

34

33

35

28

30

age 75–84, %, years

24

25

25

20

25

27

29

34

36

5

7

7

5

11

8

13

15

12

Diabetes, %

67

63

67

58

62

66

43

47

49

Hypertension, %

30

45

60

39

56

66

43

51

66

Renal disease, %

16

22

30

16

22

31

15

19

33

Ischemic heart disease, %

17

30

38

21

35

40

20

30

41

Ophthalmic complications, %

11

15

14

12

11

13

7

5

9

Neurological diabetes complications, %

14

17

18

12

14

22

10

8

11

Chronic obstructive pulmonary disease, %

9

13

16

16

18

20

19

22

23

Charlson index ≥2, %

31

39

40

44

49

53

54

55

56

age ≥85, %, years Comorbidities

*Percentages do not always add up to 100 due to rounding; †First admission CANADIAN JOURNAL OF DIABETES. 2010;34(1):58-66.

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in Table 2 for 3 sample years: 1996 (first), 2000 (middle) and 2004 (last). The absolute numbers of amputations performed has increased over time, mainly from an increase in minor amputations (toe/metatarsus/ankle). The median age of people at first amputation was 70 years, and overall the ratio of men to women was just over 2:1; this has not changed significantly over time. Women were on average 5 years older than men at first amputation. All comorbidities increased across time, with the percentage of people with hypertension increasing by 27.2% (95% CI 22.9–31.6); renal disease by 14.9% (95% CI 11.1–18.7) and ischemic heart disease by 20.4% (95% CI 16.3–24.4). The multipathology of this group is also reflected by the very high proportion (31–56%) of people scoring ≥2 on the Charlson index. Significantly more people had scored ≥2 by 2004 (X2 p<0.005), but this was driven by a rise in the score of those having amputations at the foot level (X2 p=0.0002). Figure 1 demonstrates that over the 9-year period, sex-specific, age-standardized rates of amputation have decreased among all vascular patients and those with a recorded diagnosis of diabetes. Over all time points, a linear decrease in the rate of vascular and diabetic amputations was observed for both men and women (Poisson regression model had a significant negative t term). The largest reduction was in the male vascular population, with an

overall annual decrease of 8.1% (95% CI 5.8–10.4). The overall annual decrease in female vascular amputations from 1996 to 2004 was 3.0% (95% CI 1.5–4.5). For those with a recorded diagnosis of diabetes, the annual decrease in males was 4.9% (95% CI 3.0–6.8) and in females was 1.9% (95% CI 0.7–3.1). This decrease, coupled with an increasing number of amputations (see Table 2), reflects the increasing size of the population at risk owing to aging. In-hospital mortality rates were very low for low-level amputations and for people under age 65 (1–2%); for people over age 65, the proportion dying in hospital ranged from 5–8%. For transtibial amputations, the in-hospital mortality rate was 2–4% in the younger age group and 12 to 15% for the older group. The highest mortality — 16–22% — was for people with high-level amputations, with very little difference across age groups. Length of hospital stay and discharge destination did not change over time, with the mean length of stay being 32.2 days (SD 40.3), and the median length of stay being 20 days (IQR 8.5, 40, 658) (Table 3). Most people were discharged home: 76% of foot amputees, 38% of transtibial amputees and 36% of knee disarticulation or transfemoral amputees. A total of 383 708 bed-days were directly attributed to amputation surgery over this 9-year period. The factors associated with longer length of hospital stay are presented in Table 4. Women having foot amputations,

Figure 1. Age-standardized vascular amputation rates* for Quebec, 1996–2004 25

Male all vascular Female all vascular Male diabetes vascular Female diabetes vascular

20 Rate per 100,000 population

62 |

15

10

5

0

1996

1997

1998

1999

2000

2001

2002

2003

2004

*All groups showed a statistically significant decline in amputation rates. Women had a lower rate than men. For vascular amputations, the rate ratio for women was 0.31 (95% CI: 0.29–0.34); for diabetic amputations, the rate ratio for women was 0.40 (95% CI: 0.37–0.44). There was not interaction with sex and time

AMPUtAtION IN QUebeC

Table 3. Length of hospital stay and discharge destination* Toe/metatarsus/ankle

Transfemoral/knee disarticulation

Transtibial

1996

2000

2004

1996

2000

2004

1996

2000

2004

24

23

21

42

41

51

42

40

47

82

79

78

41

34

39

35

33

36

Rehabilitation, %

0

<1

1

4

9

8

3

4

4

Long-term care, %

5

5

4

14

17

16

21

22

19

Hospital transfer, %

9

10

11

31

31

27

22

23

20

Deceased, %

3

5

5

11

9

11

19

18

20

Mean, length of stay (days) Discharge destination Home, %

Percentages do not always add up to 100 due to rounding

Table 4. Factors associated with length of stay* Toe/metatarsus/ankle† Women vs. men

Transtibial†

Transfemoral/knee disarticulation†

1.32 (1.17–1.48)

1.02 (0.88–1.19)

0.96 (0.82–1.13)

0.80 (0.67–0.96)

0.70 (0.58–0.94)

1.07 (0.78–1.48)

Age 18–54, y 55–64, y

Referent

65–74, y

1.20 (1.04–1.39)

1.10 (0.94–1.4)

1.06 (0.84–1.33)

75–84, y

1.74 (1.49–2.02)

1.04 (0.84–1.29)

0.87 (0.69–1.1)

1.74 (1.37–2.2)

0.69 (0.52–0.93)

0.68 (0.52–0.91)

0.61 (0.51–0.73)

1.22 (0.94–1.58)

0.93 (0.7–1.24)

≥85, y Charlson index 0 1

Referent

2

1.63 (1.42–1.88)

1.36 (1.13–1.64)

0.89 (0.73–1.09)

3

1.81 (1.54–2.12)

1.65 (1.31–1.99)

1.17 (0.93–1.48)

>3

2.14 (1.79–2.57)

1.59 (1.25–2.03)

1.14 (0.89–1.45)

Discharge destination Home

Referent

Rehabilitation

13.86 (7.53–25.5)

2.83 (2.06–3.91)

5.02 (3.08–8.17)

Long-term care

4.87 (3.93–6.06)

1.49 (1.19–1.85)

1.10 (0.89–1.36)

Hospital transfer

2.64 (2.27–3.07)

1.31 (1.1–1.56)

1.27 (1.03–1.57)

Death

5.33 (4.31–6.59)

1.34 (1.06–1.69)

1.32 (1.06–1.64)

12.19 (10.32–14.41)

6.51 (5.24–8.08)

10.18 (7.58–13.68)

Multiple amputations >1 amputation

*Data presented are OR (95% CI); all estimates are adjusted for all other variables in the model † >28 days vs. ≤28 days

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people having multiple amputations or people with a high Charlson index score were more likely to stay in hospital for greater than 28 days. Being discharged to anywhere but home was associated with a longer hospital stay, especially going to rehabilitation following a foot amputation.

DISCUSSION This study involving 8 464 people having 13 366 amputations due to vascular insufficiency over a 9-year period showed a considerable downturn in the rates of people having an amputation. Declines in amputation rates have been observed elsewhere, but it is difficult to compare across studies because of differences in calculation, whether all amputations (major and minor) are included, and what denominator is being used (total population, at-risk population). Why are the rates of amputation declining? One can postulate that providing better preventive care results in fewer amputations per unit population. Comprehensive prevention programs for patients with diabetes have been shown to be effective in reducing diabetes-related complications (17,18). Also, evidence-based medicine and guidelines have set tighter targets over the years and suggest more aggressive risk-factor modification for both primary and secondary prevention of vascular events and glycemic control (19–21). However, low incidence rates could also reflect a conservative approach by surgeons or less aggressive disease progression. It is also possible that outcomes of revascularization surgery have improved over this period. Although the rates of amputation have declined, the numbers of amputations performed has remained relatively stable, with a slight increase in minor amputations. Numbers of amputations reflect service need rather than change in disease profile. There is a male-dominant sex ratio in cardiovascular disease, but this female resistance is reduced by menopause. The average annual rate of peripheral vascular disease per 1000 population is 3 for men aged 35–64 years; 6 for men aged 65–94 years; 2 for women aged 35–64 years; and 3 for women aged 65–94 years (22). This male-dominant sex ratio was marked in our population, with 60–74% being male. As would be expected, the age of our population was over 65 years (median age 70 years), with females being on average 5 years older than males. Despite the decline in sex-specific, age-standardized rates of amputation, there was no decrease in the number of amputations being performed, and those undergoing multiple amputations were most at risk of having a hospital stay of more than 28 days. This group of vascular patients had a very long in-hospital length of stay (mean in 2002, 35.5 days) considering that during the same time period in Quebec, the mean length of in-hospital stay after a stroke was 22 days (23). This may be in part due to the high comorbidity burden; people may not be having an amputa-

tion until later in the disease process. The implications for this changing profile are great; for example, post-amputation care needs to address these multiple comorbidities. Amputation is very costly to those undergoing the procedure, in terms of lost ambulation and lower quality of life; it is also costly to the health service in terms of number of in-hospital days. There is no universally accepted method for determining the level of amputation for successful wound healing or the prevention of subsequent higher amputations (24). From a rehabilitation perspective, it is desirable to have a more distal level of amputation; the lower the amputation level, the lower the level of energy consumption required for ambulation (25). However, if the amputation is performed at a distal level and healing does not occur, the patient risks a longer period of inactivity and greater deconditioning. A transtibial to transfemoral amputation ratio of 2.5 is widely believed to be optimal if future mobility is to be gained, but the ratio, is in fact, usually very much below this recommendation (26); in this study, it was between 1.09 and 1.19. People with critical limb ischemia have a very limited life span, and the aim should be to avoid reconstruction, amputation and rehabilitation where possible if they are to avoid spending the rest of their lives in hospital. This may mean going straight to a higher level of amputation, where healing is assured, or a knee disarticulation, where surgery takes less time. In the Quebec population, those expected to be suitable for prosthetic rehabilitation are discharged from hospital to a rehabilitation unit or discharged home prior to admission to a rehabilitation facility. A very small proportion of transtibial and transfemoral amputees went straight to rehabilitation. This may be partially explained by the many people who had multiple amputations, the multiple comorbidities and the long hospital stay leading to deconditioning. In-hospital mortality rates were low; the increased mortality rates in higher-level amputations is probably attributable to the selection of older and “high-risk” populations, who have little prospect of rehabilitation. It has been demonstrated that 2 years after a successful transtibial amputation, 15% will have been converted to a transfemoral amputation, 15% will have had a major contralateral amputation and 30% will be dead (26). Hospitalization data alone cannot be used to identify whether the patient has had an ipsilateral or contralateral amputation, has had delayed rehabilitation or has died post-hospital discharge. Future studies are planned linking across different types of health administrative databases to complete the portrait. The major strength of using administrative data is that, in countries with public health insurance, the entire population is covered and the number of people with amputation is large. However, there are limitations due to unrecorded and/or incorrect registration of codes. It was not possible to

AMPUtAtION IN QUebeC

determine cause of amputation for 12% of the study population. These people were excluded from the vascular population examined, but as they were equally spread across the years, this should not affect estimates of change over time, although it may mean we have underestimated the number of people having vascular amputation. There may also be an underestimate of diabetes-related amputations, as prediabetes may not be recorded as a diagnosis. It is not possible to make any assertions about the appropriateness of the health services delivered or the clinical acuity of the patients, which may have changed significantly over time. To make comparisons over the years and with other countries, it would have been meaningful to be able to calculate the rate of amputation per 10 000 people with diabetes, but due to the lack of systematic basic prevalence and other diabetes information pre-2004/5, this was not possible. In future, with the utilization of the National Diabetes Surveillance System, we will be able to develop strategies to monitor data with regard to the complications of diabetes mellitus prospectively. In conclusion, despite the decline in sex-specific, agestandardized rates of amputation, there is no decrease in the number of amputations being performed. Women having foot amputations, people having multiple amputations or people with a high Charlson index score were more likely to stay in hospital for more than 28 days. The implications for the changing profile of people having amputations are great: for example, post-amputation care needs to address multiple comorbidities.

ACKNOwLEDgEMENTS Financial support received from the CDA. No other acknowledgments.

AUThOR DISCLOSURE Financial support received from the CDA.

CONTRIBUTIONS OF AUThORS DD and NM conceived, designed, analysed, interpreted the data, drafted and revised the article, and gave approval of the version to be published. SI helped design the study, interpret the data, revised the article critically for important intellectual content and gave approval of the version to be published. OS helped design the study, interpret the data, revised the article critically for important intellectual content and gave approval of the version to be published.

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