Major Lower Limb Amputation: Outcomes are Improving

Accepted Manuscript Major lower limb amputation: Outcomes are improving David A. Kelly, MBBS (Hons) BSc (Physiotherapy), Stephanie Pedersen, BEng, Patrik Tosenovsky, MD, PhD, FRACS, FEBVS, Kishore Sieunarine, MBBS FRCSE FRACS PII:

S0890-5096(17)30733-1

DOI:

10.1016/j.avsg.2017.05.039

Reference:

AVSG 3423

To appear in:

Annals of Vascular Surgery

Received Date: 8 April 2017 Revised Date:

26 May 2017

Accepted Date: 30 May 2017

Please cite this article as: Kelly DA, Pedersen S, Tosenovsky P, Sieunarine K, Major lower limb amputation: Outcomes are improving, Annals of Vascular Surgery (2017), doi: 10.1016/ j.avsg.2017.05.039. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

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Title: Major lower limb amputation: Outcomes are improving

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Running head (short title): MLLA: Outcomes are improving

3 Authors

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David A Kelly MBBS (Hons) BSc (Physiotherapy)*

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Stephanie Pedersen, BEng*

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Patrik Tosenovsky MD, PhD, FRACS, FEBVS*

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Kishore Sieunarine, MBBS FRCSE FRACS*

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*Department of Vascular Surgery, Royal Perth Hospital, Perth, Western Australia

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David Kelly

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Department of Vascular Surgery, Royal Perth Hospital, GPO BOX X2213 Perth WA 6001

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T: (08) 9224 2191 | E: [email protected]

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Key words: Amputation, outcome, vascular, mortality, complication

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Abstract

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Introduction. Outcomes following major lower limb amputation (MLLA) between 2000 and 2002

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from the department of vascular surgery at Royal Perth Hospital (RPH) have been published; mean

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postoperative length of stay 20 days, inpatient complication rate 54% and 30-day mortality 10%.

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The last decade has seen increasing endovascular revascularization techniques, increased focus on

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MLLA patients and general improvements in the model of care. The aim of this study is to compare

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outcomes between 2000-2002 and 2010-2012.

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Method. Data on all patients undergoing MLLA, trans-tibial or proximal, in the two time periods

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were extracted from the Department of Vascular Surgery database. Medical records, government

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registries and phone calls to primary care providers were used to clarify mortality.

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Results. Limb ischaemia remains the most common indication for MLLA with smoking,

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hypertension and diabetes being the main co-morbid diseases. The rates of wound infections has

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fallen 26.4% to 12.4% (p=0.023), rate of admission to ICU has fallen 48.3% to 17.5 (p=0.001) and

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revision amputation to a higher level fallen 11.5% to 7.2% (p=0.043). Acute hospital, post-

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operative length of stay has trended down from 15.74 to 20.29 days (p=0.075). Mortality overall

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has fallen from 60.92% to 46.39% (p=0.049). 30-day mortality fallen 10.34% to 5.15% (p=0.185),

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6-month 28.76% to 16.5% (p=0.046) and 1-year 40.22% to 21.65% (p=0.006).

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Conclusion. Patients undergoing MLLA still carry a high burden of co-morbid disease. With

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changes in revascularization technique, consultant supervision and multi-disciplinary model of care

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we have seen the rate of complications fall, length of stay trend down and overall mortality reduce.

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Despite improvements, outcomes remain sobering and more can be done.

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Abbreviations

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MLLA: Major lower limb amputation (Trans-tibial or proximal amputation)

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RPH: Royal Perth Hospital

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ASA: American Society of Anaesthesia

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HDA/ICU: High Dependency Area / Intensive Care Unit

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1.0 Introduction

The incidence of major lower limb amputation (MLLA), that is trans-tibial or proximal is

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between 3.8-4.8 per 100,000 Australians1. These patients are predominately old and dysvascular

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with a high burden of co-morbidity who historically have poor rates of morbidity and mortality post

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MLLA2-5. For those who survive and discharge from hospital, MLLA is profoundly disabling with

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50% of patients using a wheel chair for mobility and 25% requiring assistance for personal care6-8.

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Between 2000-2002 at our institution 87 vascular patients underwent MLLA. Mean

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postoperative length of stay was 20 days, 53.5% were fitted with prosthesis, the inpatient

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complication rate was 54% and 12-month mortality was 43.1%. Since 2002 our institute increased

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the consultant supervision for MLLA patients. Overall there has been greater collaboration with

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inpatient medical specialists and the multi-disciplinary team. Nursing developments include patient

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observation charts with an incorporated algorithm to detect physiological derangement. Hospital

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wide there has also been the development of a ‘MET’ rapid response team including anaesthetics,

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intensive care and general medicine along with senior nursing staff to respond rapidly to

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deteriorating patients on the wards. The aim of this study is to re-examine the outcomes for MLLA

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between 2010-2012 after a decade of change.

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2.0 Method

The data collection mirrored the method used for the previous study of the period 2000-

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2002 7. Patients admitted under the Department of Vascular Surgery who underwent a MLLA were

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identified from the Department of Vascular Surgery’s electronic audit database. This data is

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prospectively recorded and we extracted demographics, comorbidities, level of amputation,

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previous vascular procedures, previous amputations, complications and mortality statistics for

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patients who underwent MLLA. Further information, such as prosthesis use was collected from the

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medical record. Mortality was clarified through the public hospital electronic database, cemeteries

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board along with phone calls to patients, next of kin and general practitioners. Statistics on Page 3 of 12

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admissions and theatre cases were extracted from the hospitals electronic patient management

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systems using ICD10 and medicare billing codes. Data collection was completed on the 31st

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December 2004 with a mean follow up 3.35 ±0.83 years for the 2000-2002 patients and 31st January

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2014, mean follow up 3.60 ± 8.8 years for 2010-2012 cohort. Raw data for the 2000-2002 and 2010-2012 periods were recorded into Microsoft Excel and

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exported to SPSS (version 23) for statistical analysis. Pearson Chi-square was used for univariate

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analysis and t-test for comparison of means with a P value <0.05 considered statistically significant. Royal Perth Hospital (RPH) at the time of this study was the largest tertiary hospital in

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Western Australia. Patients in this study underwent MLLA performed by vascular surgeons, it does

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not include those undergoing MLLA by the orthopaedic or trauma surgeons.

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Ethics approval was obtained for this study from the RPH Human Research Ethics Committee. Reference number REG 15-039.

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3.0 Results

The Department of Vascular Surgery performed 97 MLLA in the period 2010-2012, an

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increase from 87 in 2000-2002. Overall patient admissions increased by 14% (2163 to 2471

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patients) however those for lower limb angiopathy and infection reduced by 8% (890 to 818

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patients). Total operative cases increased by 61% (1864 to 3019 cases), lower limb

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revascularization procedures for arterial occlusive disease increased by 2.3% (344 to 352) with a

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236% increase in endoluminal procedures (65 to 219) and 52% reduction in open procedures (279

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to 133). MLLA as a percentage of all lower limb amputations has fallen from 39% to 30%.

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In 2000-2002 there were 51 trans-tibial, 5 through-knee and 31 transfemoral amputations

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with a ratio 1.65:1. For the 2010-2012 time period 58 patients underwent trans-tibial and 39 trans-

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femoral amputations; a ratio of 1.4:1. In 2010-2012 17 patients had a contralateral MLLA at time of

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admission (13 trans-tibial and 4 trans-femoral), at the end of follow up a further 13 patients

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underwent contralateral MLLA in a subsequent admission resulting in 30 bilateral amputees Page 4 of 12

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(30.9%) a similar finding from 2000-2002 where 29 patients (33.3%) were bilateral amputees at the

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end of data collection.

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In 2010-2012, limb ischaemia remained the most common indication for MLLA in vascular patients accounting for 71 (73.2%) cases. Diabetic foot infection (18.6%) and non-diabetic infections (8.2%) accounted for the remaining cases.

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There has been an increase in the number of MLLA performed by the consultant. In 2000-

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2002 4.1% of MLLA’s were performed by the consultant; 60.3% by a training registrar and 35.6%

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performed by service (non-training) registrars or junior medical officer. In 2010-12, 38.1% of

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MLLA’s were performed by the consultant; 57.8% by a training registrar and 4.1% performed by

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the service registrar or junior medical officer.

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3.1 Co-morbid disease state

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Prior to amputation more patients are undergoing revascularization procedures with 43

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procedures performed in 39 patients in 2000-2002 versus 46 procedures in 45 patients in 2010-

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2012. [Refer Table 1 and Table 2].

Number of patients with a contralateral MLLA at time of admission has increased from 9 (10%) to 17 (19%).

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3.2 Inpatient Complications

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Forty-four patients (45%) suffered one or more inpatient complications. [Refer table 3] Of the 12 patients with a wound infection, four required a return to theatre. Of the 11 patients returning

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to theatre, four were for wound debridement alone, six for revision to higher level and one patient

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had repeat debridement followed by revision to higher level. Two patients were palliated in the

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acute hospital, one post cerebrovascular accident, the other post myocardial infarction.

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3.3 Length of stay

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Time from admission to amputation has fallen from 11 days in 2000-2002 (SD 14.9 range 0-

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73 days) to 3.7 days in 2010-2012 (SD 4.9 Range 0-31 days). Mean time of admission to

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amputation was longer in patients who underwent revascularization procedure prior to MLLA in the Page 5 of 12

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same admission 3.33 vs. 7.10 days (p = 0.02). The mean post-operative length of stay in an acute

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hospital for the period 2010-2012 was 15.74 days compared with 20.29 days in the 2000-2002

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period (p=0.075). The mean acute post op length of stay for those transferred to rehab was 11.43

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days (SD 7.089 Range 1-32) compared to those transferred home, to residential care, hospice or

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other hospital 18.77 days (SD 16.79 Range 1-86) (p=0.011).

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Fifty-three patients were discharged home or to their residential care facility from the acute hospital, four patients died during their acute inpatient stay and the remaining 40 patients were

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transferred into a rehabilitation hospital. The mean length of stay in rehabilitation was 35.78 days

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(SD 18.62 Range 9-91) for the period 2010-2012 compared with 47.05 days (SD 32.4 Range 8-168)

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for the period 2000-2002 (p=0.051)

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3.4 Mortality

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At the conclusion of data collection 45 (46.4%) patients had died; 5 patients as an inpatient

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(acute / rehabilitation / hospice), the remaining post discharge from hospital. Age at time of MLLA

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was associated with increased mortality with the mean age at MLLA of survivors overall 63.51

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years versus 74.44 years for those deceased (p<0.01) at time of data collection. [Refer table 4]

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3.5 Prosthesis use

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Seventeen patients (17.5%) died before they were considered for prosthesis leaving 80

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eligible patients. Twenty-seven (33.75%) were fitted with a prosthesis compared with 38 (53.5%) of

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71 eligible patients in 2000-2002. In 2010-2012, 15.6% of trans-femoral amputees versus 45.8% of

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trans-tibial amputees had prosthesis fitted (p = 0.005), three of the seventeen patients with a

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contralateral MLLA at time of admission received prosthesis, all three were bilateral trans-tibial

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amputees.

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Co-morbid disease was a significant factor for prosthesis fitting with 27.4% of those with 3

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or more co-morbidities vs. 55.6% of those with two or fewer having prosthesis fitted (p = 0.026).

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Of the 27 patients fitted for prosthesis, 44.4% were not using their prosthesis on discharge

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from hospital, 11.2% were using it only indoors and 44.4% were using their prosthesis indoors and Page 6 of 12

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outdoors. Overall 46.3% of patients fitted with prosthesis were using a wheelchair as their primary

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mode of mobility on discharge from rehabilitation hospital.

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The most common reason for a prosthesis not being fitted was poor premorbid mobility and dependence on care for personal activities of daily living. The presence of bilateral MLLA, age,

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wound breakdown and palliation were the remaining reasons documented.

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4.0 Discussion

Australia has low rates of MLLA9 and the number of MLLA performed by The Department

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of Vascular Surgery remains stable. The department is performing more endovascular than open

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revascularization procedures, more patients are managed as an outpatient and the rate of major

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versus minor lower limb amputations is falling which reflects what is known about MLLA

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nationally 1.

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The patients undergoing MLLA are older, predominately male and have a high incidence of co-morbid disease6, 10. Consistent with changes in demographics across the Australian population,

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we have seen a reduction in the rates of smokers but an increase in the number of diabetics11, 12. At

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the time of surgery, the mean ASA score for MLLA patients is 3.26 (±0.65) where ASA 3 equals

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severe systemic disease and ASA 4 is severe systemic disease that is a constant threat to life.

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There has been a reduction in the rates of prosthesis fitting and use on discharge from

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hospital, falling 54.05% to 33.75% for MLLA between 2000-02 and 2010-2012 (p=0.011). Falling

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complications and lower rates of dementia are favorable for prosthesis use however the poor ratio of

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trans-tibial to trans-femoral amputation and increased number of patients with contralateral

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amputation are likely to negatively impact on prosthesis use 8. There has also been a change in

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rehabilitation practice whereby increasingly patients are discharged home and have their prosthesis

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fitted as an outpatient 13. Our method of data collection fails to detect these patients, reflects a

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limitation of the study and may explain the reduced rate of prosthesis use. The level of amputation,

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premorbid function, presence of contralateral MLLA on admission and rates of co-morbid disease

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still remain critical factors in the fitting of prosthesis.

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Since 2000-2002 consultants involvement in MLLA has significantly increased however only the lead surgeon was recorded and information on presence of assistant, the level of training of

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the assistant and degree of supervision were not recorded.

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Rates of complications have fallen over the study period from 54% to 45%, 2000-2002 to 2010-2012 respectively. Significantly there are fewer admissions to the high dependency or

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intensive care unit, which may reflect the earlier detection of deterioration of patients on the ward

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and faster care provided by the ‘MET’ team. Fewer wound infections and fewer revision

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amputations to a higher level likely reflect the impact of greater senior surgeon involvement in the

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management of MLLA. Overall rates were consistent with previous reported MLLA series and not

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significantly altered by the patient’s age, gender, ASA score or premorbid condition 14,15.

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Mortality post MLLA remains high, however overall figures at 30 days, 6 months and 1 year have almost halved over the decade. Increased mortality continues to be associated with gender,

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age, co-morbid status, ASA and level of amputation. Recent publication in the NHS puts 1year

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mortality at 35.7% 16 and Medicare patients in the United States at 48.3% 17. Whilst patient factors have an impact on the outcome, the overall improvement in mortality,

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complications and length of stay is likely multi-factorial. Improvements in the general medical

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management of diabetes, peripheral vascular and ischaemic heart disease, the reductions in smoking

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in the community and the advances in revascularization surgery all impact on outcomes 18. Changes

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specific to RPH that may have improved outcomes include improved recognition of the

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deteriorating patient, the ‘MET’ team and streamlined access to multi-disciplinary consultations and

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collaborative management of MLLA patients on the ward for those with complex co-morbidities.

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This study has limitations typical of a retrospective analysis. The accuracy of data is

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dependent on the note taking of colleagues and whist audit is a valuable tool there are also gaps in

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the data once the patient is discharged. We were resourced to further examine mortality data but the

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same was not able for other variables such as prosthesis use.

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Overall MLLA has a significant impact on functional capacity and carries considerable risk of complication and mortality in a co-morbidly unwell cohort of patients. With evolving

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endovascular techniques, increased consultant supervision, rapid detection and action for

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deteriorating patients and multi-disciplinary team approach outcomes can be improved. There is

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however more work to be done.

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5.0 References

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1. Dillon, M. P., Kohler, F., & Peeva, V. (2014). Incidence of lower limb amputation in Australian

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hospitals from 2000 to 2010. Prosthetics and Orthotics International, 38 (2), 122-132.

209 2. van Netten, J. J., Fortington, L. V., Hinchliffe, R. J., & Hijmans, J. M. (2015). Early port-

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operative mortality after major lower limb amputation: A systematic review of population and

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regional based studies. European Journal of Vascular and Endovascular Surgery, 1-11.

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3. Lavery, L. A., Hunt, N. A., Ndip, A., Lavery, D. C., Van Houtum, W., & Boulton, A. J. (2010).

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Impact of chronic kidney disease on survival after amputation in individuals with diabetes. Diabetes

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Care, 33 (11), 2365-2369.

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4. Remes, L., Isoaho, R., Vahlberg, T., Hiekkanen, H., Korhonen, K., Viitanen, M., et al. (2008).

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Major lower extremity amputation in elderly patients with peripheral arterial disease: incidence and

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survival rates. Aging Clinical and Experimental Research, 20 (5), 385-393.

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5. Eskelinen, E., Lepantalo, M., Hietala, E. M., Sell, H., Kauppila, L., Maenpaa, I., et al. (2004).

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Lower limb amputations in southern Finland in 2000 and trends up to 2001. European journal of

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vascular and endovascular surgery, 27 (2), 193-200.

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6. Batten, H. R., Kuys, S. S., McPhail, S. M., Varghese, P. N., & Nitz, J. C. (2015). Demographics

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and discharge outcomes of dysvascular and non-vascular lower limb amputees at a sub acute

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rehabilitation unit: a 7-year series. Australian Health Review, 39 (1), 76-84.

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7. Lim, T. S., Finlayson, A., Thorpe, M. J., Sieunarine, K., Mwipatayi, B. P., Brady, A., et al.

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(2006). Outcomes of a Contempory Amputation Series. Australian and New Zealand Journal of

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Surgery, 76, 300-305.

233 8. Nehler, M. R., Coll, J. R., Hiatt, W. R., Regensteiner, J. G., Schnickel, G. T., Klenke, W. A., et

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al. (2003). Functional outcome in a contempory series of major lower extremity amputations.

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Journal of Vascular Surgery, 38 (1), 7-14.

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9. The Global Lower Extremity Amputation Study Group. (2000). Epidemiology of lower extremity

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amputation in centres in Europe, North America and East Asia. British Journal of Surgery, 87 (3),

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328-337.

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10. Hordacre, B. G., Stevermuer, T., Simmonds, F., Crotty, M., & Eagar, K. (2013). Lower-limb

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amputee rehabilitation in Australia: analysis of a national data set 2004-2010. Australian Health

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Review, 37 (1), 41-47.

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11. Australian Bureau of Statistics. (2007). Article: Diabetes Mellitus. Canberra: Australian Bureau

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of Statistics.

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12. Australian Bureau of Statistics. (2015). National Health Survey First Results Australia 2014-

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2015. Canberra: Australian Bureau of Statistics.

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13. Roffman, C E, Buchanan K and Allison G T. (2014). Predictors of non-use of prostheses by

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people with lower limb amputation after discharge from rehabilitation: development and validation

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of clinical prediction rules. Journal of Physiotherapy, 60, 224-231

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14. Sadat, U., Chaudhuri, A., Hayes , P. D., Gaunt, M. E., Boyle, J. R., & Varty, K. (2008). Five

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Day Antibiotics Prophylaxis for Major Lower Limb Amputation Rates and the Length of In-

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hospital Stay. European Journal of Vascular and Endovascular Surgery, 35 (1), 75-78.

258 15. Belmont, P. J., Davey, S., Orr, J. D., Ochoa, L. M., Bader, J. O., & Schoenfield, A. J. (2011).

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Risk factors for 30-day post operative complications and mortality after below-knee amputation: a

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study of 2911 patients from the national surgical quality improvement program. Journal of the

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American College of Surgeons, 213 (3), 370-378.

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16. Scott, S. W., Bowrey, S., Clarke, D., Choke, E., Bown, M. J., & Thompson, J. P. (2014).

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Factors influencing short and long term mortality after lower limb amputation. Anaesthesia, 69 ,

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249-258.

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17. Schuyler Jones, W., Patel, M. R., Dai, D., Vemulapalli, S., Subherwal, S., Stafford, J., et al.

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(2013). High mortality risks after major lower extremity amputation in Medicare patients with

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peripheral vascular disease. American Heart Journal, 165 (5), 809-815.

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18. Ergorova, N. N., Guillerme, S., Gelijns, A., Morrissey, N., Dayal, R., McKinsey, J. F., et al.

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(2010). An analysis of the outcomes of a decade of experience with lower extremity

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revascularization including limb salvage, lengths of stay and safety. Journal of Vascular Surgery, 51

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(4), 878-885.

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ACCEPTED MANUSCRIPT Table 1. Patient Co-morbidities between periods 2000-2002 (n=87)

2010-2012 (n=97)

Age; Mean

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68

(p=0.486)

Gender; Male

67 (77%)

66 (68%)

(p=0.175)

Diabetes

43(49.4%)

62 (63.9%)

(p=0.047)

Smoking history †

71 (81.6%)

64 (66.0%)

(p=0.017)

Chronic Obstructive Airways Disease

22 (25.3%)

6 (6.2%)

(p=0.00)

Dementia

18 (18.4%)

7 (7.2%)

(p=0.022)

Hypercholesterolaemia

25 (28.7%)

41 (42.3%)

(p=0.56)

Hypertension

67 (77%)

71 (73.23%)

(p=0.551)

Ischaemic Heart Disease

51 (58.6%)

49 (50.5%)

(p=0.270)

Acute Myocardial Infarction

26 (29.9%)

31 (32.0%)

(p=0.761)

Atrial Fibrillation

24 (27.6%)

28 (28.9%)

(p=0.847)

Cerebrovascular accident

22 (25.3%)

20 (20.6%)

(p=0.451)

Raised serum creatinine ‡

30 (34.5%)

27 (27.8%)

(p=0.330)

Buergers Disease

2 (2.3%)

2 (2.1%)

(p=0.812)

Score 1

2 (2.3%)

1 (1%)

Score 2

6 (6.9%)

5 (5.2%)

Score 3

59 (67.8%)

62 (62.9%)

Score 4

20 (23.0%)

26 (26.8%)

Score 5

0 (0%)

3 (3.1%)

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ASA §

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(p=0.441)

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† Current and Ex-smoker ‡ Creatinine above 105 micromol/L §ASA American Society of Anaesthetic Score

ACCEPTED MANUSCRIPT Table 2. Vascular interventions prior to MLLA Vascular intervention

2000-2002 (n=87)

2010-2012 (n=97)

Procedure prior to admission for MLLA 38 (43.7%)

52 (53.6%)

p=0.187

Angioplasty

10 (11.5%)

24 (24.7%)

p=0.023

Thrombectomy

2 (2.3%)

3 (3.1%)

p=1.00

Embolectomy

0

1 (1%)

P=1.00

Arterial Bypass

14 (16.1%)

18 (18.6%)

Revascularization (any)

25 (28.7%)

36 (37.1%)

Ipsilateral toe or foot amputation

15 (17.2%)

15 (15.4%)

Procedure in same admission as MLLA

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p=0.701

p=0.273 p=0.449

32(36.8%)

26 (26.8%)

Angioplasty

4 (4.6%)

7 (7.2%)

p=0.543

Thrombectomy

3 (3.4%)

2 (2.1%)

p=0.668

Embolectomy

0

3 (3.1%)

p=0.248

Arterial Bypass

13 (14.9%)

2 (2.1%)

p=0.002

Revascularization (any)

18 (20.7%)

10 (10.3%)

p=0.064

Ipsilateral toe or foot amputation

13 (14.9%)

6 (6.1%)

p=0.057

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Angiogram

p=0.156

ACCEPTED MANUSCRIPT Table 3. Inpatient complications between periods 2000-2002 (n=87)

2010-2012 (n=97)

p-value

Any complication

47 (54.0%)

44 (45.4%)

p=0.3

Admission to HDA/ICU ¶

42 (48.3%)

17 (17.5%)

p=0.00

Wound infection

23 (26.4%)

12 (12.4%)

p=0.023

Return to operating theatre

16 (18.4%)

11 (11.3%)

p=0.213

Repeat debridement

8 (9.2%)

5 (5.1%)

p=0.390

Revision amputation to higher level

10 (11.5%)

7 (7.2%)

Myocardial infarction

10 (11.5%)

2 (2.1%)

Cerebrovascular accident

2 (2.3%)

1 (1%)

Pneumonia

6 (6.9%)

3 (3.1%)

Anaemia #

18(20.7%)

15 (15.5%)

AC C

EP

TE D

SC

M AN U

¶ HDA/ICU: High Dependency Area / Intensive Care Unit # Haemoglobin <115g/L in females or <135g/L in males

RI PT

Inpatient Complication

p=0.043

P=0.014

P=0.603

P=0.311

P=0.442

ACCEPTED MANUSCRIPT Table 4. Factors associated with mortality 30 day mortality

6 month mortality

1 year mortality

%

%

%

2010-2012

5.1% 1.5%

Gender Female

12.9%

Age ≤65

0%

Age ≥ 66

5%

Level – trans-tibial

1.7%

Level – trans-femoral

10.3%

ASA ≤ 3

1.5%

ASA ≥ 4

13.8%

Co-morbidities ≤ 4

0

Co-morbidities ≥ 5

11.1%

28.8%

0.046

16.5% 0.035

9.1%

0.007

32.3% 0.153

5.4% 23.3%

0.154

8.6% 28.2%

0.027

13.2%

11.5% 22.2%

TE D EP AC C

0.006

13.6%

0.008

38.7% 0.024

8.1%

0.012

30%

0.023

10.3%

0.002

38.5%

0.234

24.1% 0.019

40.2%

p-value

21.6%

M AN U

Gender Male

0.185

p-value

RI PT

10.3%

2010 - 2012

2000-2002

p-value

SC

Variable

0.180

16.2%

0.060

34.5% 15.4% 28.9%

0.140