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Editor's Choice: Contemporary Treatment of Popliteal Artery Aneurysm in Eight Countries: A Report from the Vascunet Collaboration of Registries

Open AccessPublished:November 27, 2013DOI:https://doi.org/10.1016/j.ejvs.2013.10.026

      Objectives

      To study contemporary popliteal artery aneurysm (PA) repair.

      Methods

      Vascunet is a collaboration of population-based registries in 10 countries: eight had data on PA repair (Australia, Finland, Hungary, Iceland, New Zealand, Norway, Sweden, and Switzerland).

      Results

      From January 2009 until June 2012, 1,471 PA repairs were registered. There were 9.59 operations per million person years, varying from 3.4 in Hungary to 17.6 in Sweden. Median age was 70 years, ranging from 66 years in Switzerland and Iceland to 74 years in Australia and New Zealand; 95.6% were men and 44% were active smokers.
      Elective surgery dominated, comprising 72% of all cases, but only 26.2% in Hungary and 39.7% in Finland, (p < .0001). The proportion of endovascular PA repair was 22.2%, varying from 34.7% in Australia, to zero in Switzerland, Finland, and Iceland (p < .0001). Endovascular repair was performed in 12.2% of patients with acute thrombosis and 24.1% of elective cases (p < .0001). A vein graft was used in 87.2% of open repairs, a synthetic or composite graft in 12.7%.
      Follow-up was until discharge or 30 days. Amputation rate was 2.0% overall: 6.5% after acute thrombosis, 1.0% after endovascular, 1.8% after open repair, and 26.3% after hybrid repair (p < .0001). Mortality was 0.7% overall: 0.1% after elective repair, 1.6% after acute thrombosis, and 11.1% after rupture.

      Conclusions

      Great variability between countries in incidence of operations, indications for surgery, and choice of surgical technique was found, possibly a result of surgical tradition rather than differences in case mix. Comparative studies with longer follow-up data are warranted.

      Keywords

      Popliteal artery aneurysm is the most common peripheral aneurysm, yet data on this disease are limited. The great differences between countries regarding the treatment of popliteal artery aneurysm, found in this descriptive study, are thought-provoking and will, hopefully, result in more focused research in the future. The vascular registries need to be revised and collect more precise data on pathology, indication, treatment and outcome in the future, and those variables described herein.

      Introduction

      Popliteal artery aneurysm (PA) is the most commonly treated extracranial aneurysm outside of the aorta, and thus constitutes an important clinical problem. Despite this, the disease is rare and difficult to study with a scientific approach. In Sweden, between 1994 and 2001, the incidence of PA repair was only 8.3 per million person years.
      • Ravn H.
      • Bergqvist D.
      • Björck M.
      Nationwide study of the outcome of popliteal artery aneurysms treated surgically.
      Consequently, most previous reports on PA are case series from single institutions.
      • Pulli R.
      • Dorigo W.
      • Troisi N.
      • Innocenti A.A.
      • Pratesi G.
      • Azas L.
      • et al.
      Surgical management of popliteal artery aneurysms: which factors affect outcomes?.
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      • Pedersen G.
      • Aune S.
      Surgical treatment of popliteal artery aneurysms.
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      • Colgan M.P.
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      • Shanik G.D.
      Popliteal aneurysms: a 10-year experience.
      • Davidovic L.B.
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      • Markovic D.M.
      • et al.
      Popliteal artery aneurysms.
      One prospective multi-centre study was published from the UK Joint Vascular Research Group in 1994.
      • Varga Z.A.
      • Locke-Edmunds J.C.
      • Baird R.N.
      A multicenter study of popliteal aneurysms. Joint Vascular Research Group.
      Two large observational studies, based on prospectively reported data collected from vascular centres in Sweden
      • Ravn H.
      • Bergqvist D.
      • Björck M.
      Nationwide study of the outcome of popliteal artery aneurysms treated surgically.
      and the USA,
      • Johnson 3rd, O.N.
      • Slidell M.B.
      • Macsata R.A.
      • Faler B.J.
      • Amdur R.L.
      • Sidaway A.N.
      Outcomes of surgical management for popliteal artery aneurysms: an analysis of 583 cases.
      and supplemented by review of the patient's records, were published in 2007–2008. The Swedish study also re-examined patients a median 7 years after PA repair, and reported a very high frequency of multiple aneurysm disease: abdominal aortic aneurysm (AAA), bilateral PAs, and of other extracranial peripheral aneurysms.
      • Ravn H.
      • Wanhainen A.
      • Bjorck M.
      Risk of new aneurysms after surgery for popliteal artery aneurysm.
      In recent years, many investigators have reported single centre experiences on an increased use of endovascular repair of PA, although one of the pioneers in this treatment, the Groningen group, reported a high frequency of stent-fractures after endovascular repair.
      • Tielliu I.F.J.
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      • van den Dungen J.J.A.M.
      • Prins T.R.
      • et al.
      Stent fractures in the Hemobahn/Viabahn stent graft after endovascular popliteal aneurysm repair.
      Galiñanes et al.
      • Galiñanes E.L.
      • Dombrovskiy V.Y.
      • Graham A.M.
      • Vogel T.R.
      Endovascular versus open repair of popliteal artery aneurysms; outcomes in the US medicare population.
      recently reported an investigation on patients operated on for lower extremity artery aneurysms, predominantly, but not exclusively, PAs, from the Medicare & Medicaid database 2005–2007. A total of 2,962 patients was identified and endovascular interventions significantly increased over this short timespan, from 12% to 24%. No data on the use of endovascular PA repair in large populations outside of the USA exist.
      Vascunet is a collaboration of population-based registries in Europe, Australia, and New Zealand that started in 1997.
      • Björck M.
      • Gibbons C.
      • Jensen L.P.
      • Laustsen J.
      • Lees T.
      • Moreno-Carriles R.
      • et al.
      Vascular registries join and create the common European dataset on AAA surgery.
      At present, 10 countries contribute to the common database, and previous reports on AAA repair,
      • Mani K.
      • Lees T.
      • Beiles B.
      • Jensen L.P.
      • Venermo M.
      • Simo G.
      • et al.
      Treatment of abdominal aortic aneurysm in nine countries 2005–2009: a Vascunet report.
      carotid endarterectomy,
      • Menyhei G.
      • Björck M.
      • Beiles B.
      • Halbakken E.
      • Jensen L.P.
      • Lees T.
      • et al.
      Outcome following carotid endarterectomy: lessons learned from a large international vascular registry.
      • Vikatmaa P.
      • Mitchell D.
      • Jensen L.P.
      • Beiles B.
      • Björck M.
      • Halbakken E.
      • et al.
      Variation in clinical practice in carotid surgery in 9 countries 2005–2010. Lessons from VASCUNET and recommendations for the future of national clinical audit.
      and lower limb bypass surgery
      • Lees T.
      • Troëng T.
      • Thomson I.A.
      • Menyhei G.
      • Simo G.
      • Beiles B.
      • et al.
      International variations in infrainguinal bypass surgery – a VASCUNET report.
      have been published. The aim of this investigation was to explore the contemporary treatment of PA in the collaborating countries.

      Methods

      In May 2012 the 10 collaborating national and regional registries were invited to participate, and a common set of variables was agreed upon. Denmark was not able to distinguish PA from other peripheral aneurysms of the lower limb, that is, from femoral aneurysms in their databases, and could therefore not participate in this investigation. The UK did not have any data on endovascular repair, and also had difficulties in distinguishing PA from other peripheral aneurysms of the lower limb. Finland submitted data from the Helsinki and Vaasa regions only. In all, data from eight countries were included.
      A common dataset was agreed upon (Table 1), that is, participant registries recoded their data to conform to this common format. Not all registries could provide all the variables (see ‘Results’). A hybrid procedure was defined as an open surgical and an endovascular operation being performed simultaneously. The registries in Finland, Iceland, Norway, and Sweden register follow-up at 30 days and the others at discharge.
      Table 1Popliteal aneurysm data dictionary.
      FieldsDescription on formPossible responsesFormat of field
      CountryCountryAUS, NZ, UK, Sweden, DM, Finland, Hungary, Italy, SwitzerlandText
      Hospital IDHospital dode or identifierNumber/letter combinationText
      Patient ageAge of patient at the time of surgeryWhole numberInteger
      Patient IDPatient identifier (allocated by country and anonymised)Number/letter combinationText
      GenderSexMale, female1 = male, 2 = female
      Admission dateDate of admissionDatedd/mm/yyyy
      Admission modeMode of admissionElective, emergency1 = elective, 2 = emergency
      DiabetesDiabetesYes or no0 = no, 1 = yes
      Cardiac historyCardiac history—any IHD or CCFYes or no0 = no, 1 = yes
      Current smokerCurrent smoker (within 2 months)Yes or no0 = no, 1 = yes
      Pulmonary historySymptomatic lung diseaseYes or no0 = no, 1 = yes
      Cerebrovascular eventPrevious stroke or TIAYes or no0 = no, 1 = yes
      History
      Hypertension historyHypertensionYes or no0 = no, 1 = yes
      Preoperative data
      IndicationIndication for surgeryElective, emergency thrombosis, emergency rupture1 = elective, 2 = emergency thrombosis, 3 = emergency rupture
      Side of operationSide of symptomatic legRight or left1 = right, 2 = left
      ABIAnkle brachial pressure indexNumber to 1 decimal pointNumber (0–1.5)
      Operative data
      Operation dateDate of operationDate dd/mm/yyyy
      ProcedureEndovascular or open surgeryEndovascular, open, hybrid1 = endovascular, 2 = open surgery, 3 = hybrid
      Access routeAccess routeMedial, dorsal, other, endovascular1 = medial, 2 = dorsal, 3 = other, 4 = endovascular
      Proximal anastomosis siteAnatomic site of proximal anastomosisIliac, femoral, popliteal, other1 = iliac, 2 = femoral, 3 = popliteal, 4 = other
      Distal anastomosis siteAnatomic site of distal anastomosisPopliteal above knee, popliteal below knee, crural, pedal, other1 = popliteal above knee, 2 = Popliteal below knee, 3 = crural, 4 = pedal, 5 = other
      Graft typeType of graftVein, synthetic, composite1 = Vein, 2 = synthetic, 3 = composite
      Additional open procedureAdditional open procedure at time of surgeryYes or no0 = no, 1 = yes
      AEPAEP at time of surgeryYes or no0 = no, 1 = yes
      Preoperative thrombolysisPreoperative thrombolysisYes or no0 = no, 1 = yes
      Perioperative thrombolysisPerioperative thrombolysisYes or no0 = no, 1 = yes
      Follow-up (in hospital or 30 days)
      Discharge dateDate of dischargeDate dd/mm/yyyy
      Wound complication (WC)WC leading to surgical interventionYes or no0 = no, 1 = yes
      HaemorrhageReoperation for haemorrhageYes or no0 = no, 1 = yes
      Compartment syndrome (CS)CS requiring fasciotomyYes or no0 = no, 1 = yes
      Graft patent at dischargeGraft patent at dischargeYes or no0 = no, 1 = yes
      Graft patent at 30 daysPatent graft at 30 daysYes or no0 = no, 1 = yes
      AmputationAmputation at ankle or higher on ipsilateral sideYes or no0 = no, 1 = yes
      ABIAnkle brachial pressure indexNumber to 1 decimalNumber (0–1.5)
      Acute coronary eventAcute coronary syndrome, MI, serious arrhythmia, cardiac failureYes or no0 = no, 1 = yes
      Major strokeMajor strokeYes or no0 = no, 1 = yes
      Died within 30 days of surgeryDeceased at 30 daysYes or no0 = no, 1 = yes
      Date of deathDate of death (if known)Date dd/mm/yyyy
      Data based on hospital discharge or 30 days?Follow-up timeDischarge or 30 days1 = discharge, 2 = 30 days
      Note. ID = identification; IHD = ischaemic heart disease; CCF = congestive cardiac failure; TIA = transient ischaemic attack; AUS = Australia; NZ = New Zealand; DM = Denmark; AEP = additional endovascular procedure; MI = myocardial infarction.
      Statistical comparisons were performed with Fisher's exact test for dichotomous variables (such as amputations), when two groups were compared. When multiple countries were compared, either analysis of variance or Pearson's chi-square test with different degrees of freedom were used as appropriate.

      Results

      The operations were performed between January 2009 and June 2012, and a total of 1,471 PA repairs were included in the common database. Time periods and catchment areas differed, as described in Table 2. Most repairs (77.1%) were performed between 2010 and 2011, 19.1% during 2009 and only 3.8% during 2012. The largest number of cases was submitted from Sweden (495; 34%) and Australia (441; 30%); the remaining countries/regions constituted 36% of the database. The overall number of operations per million person years was 9.59, but varied considerably, from 3.4 in Hungary to 17.6 in Sweden.
      Table 2Participating countries, time periods, population covered, number of operations, and incidence of operations per million inhabitants.
      CountryTime periodPopulation

      millions
      Number of operationsOperations/million inhabitants/year
      Australia2010–201122.54419.9
      Finland (Helsinki)
      Finland included defined regional data.
      2009–20111.37
      Finland included defined regional data.
      5813.9
      Hungary2009–2012
      The countries including 2012 only included the first 3–6 months of that year.
      9.961033.4
      Iceland2009–20110.3565.7
      Norway2009–2012
      The countries including 2012 only included the first 3–6 months of that year.
      4.718811.9
      New Zealand2010–2012
      The countries including 2012 only included the first 3–6 months of that year.
      4.4937.0
      Sweden2009–20119.549517.6
      Switzerland
      The Swiss registry covers approximately 70% of the entire population of eight million inhabitants.
      2009–20115.6
      The Swiss registry covers approximately 70% of the entire population of eight million inhabitants.
      875.2
      All2009–201258.414719.59
      Note. The other countries included national data.
      a Finland included defined regional data.
      b The countries including 2012 only included the first 3–6 months of that year.
      c The Swiss registry covers approximately 70% of the entire population of eight million inhabitants.
      The median age of the patients was 70 years, ranging from 66 years in Switzerland and Iceland to 74 years in Australia and New Zealand. As expected, most patients (95.6%) were men. The 64 women had a median age of 73.5 years, which was not significantly older than the men (p = .46). The small number of women reduced the power when analysing gender differences. The proportion of patients ≥80 years of age was 19.2% among men and 18.8% among women.
      The risk factors diabetes, cardiac history, pulmonary history and hypertension were registered in almost 100% of cases, cerebrovascular event in 54.8% and smoking history in 91.5%. Overall and national prevalences of the risk factors are given in Table 3; differences between countries were all statistically significant (p < .0001).
      Table 3Prevalence of preoperative risk factors. All values are given as percentages.
      Risk factorAllAusFinHunIceNorNZSweSwip
      p-Values refer to differences between countries.
      Cardiac history37.150.148.339.850.041.537.623.427.6<.0001
      Pulmonary history14.0miss15.519.40.015.4miss9.510.3<.0001
      Hypertension72.483.277.686.466.758.075.362.283.9<.0001
      Cerebrovascular event9.0miss10.3miss0.012.2miss8.74.6<.0001
      Diabetes16.216.620.726.233.316.012.913.319.5<.0001
      Current smoking44.076.246.347.616.737.28.621.457.5<.0001
      Note. All = average proportion of all countries with data; Aus = Australia; Fin = Finland; Hun = Hungary; Ice = Iceland; Nor = Norway, NZ = New Zealand; Swe = Sweden; Swi = Switzerland; miss = missing data in this particular registry.
      a p-Values refer to differences between countries.
      The indication for treatment varied considerably between the countries (p < .0001) (Table 4). Elective surgery dominated in most countries, accounting overall for 72% of cases, but it was as low as 26.2% in Hungary and 39.7% in Finland.
      Table 4Indications for treatment of popliteal artery aneurysm in the different countries studied.
      CountryAll (n)Elective surgery (n)%Emergency surgery (n)
      Most emergency operations were performed for acute thrombosis and/or embolism, but 27 patients (1.8%) were operated on for rupture (six in Australia, 11 in Norway, and 10 in Sweden).
      %
      Australia
      Most emergency operations were performed for acute thrombosis and/or embolism, but 27 patients (1.8%) were operated on for rupture (six in Australia, 11 in Norway, and 10 in Sweden).
      44138086.26113.8
      Finland (Helsinki)582339.73560.3
      Hungary1032726.27673.8
      Iceland6610000.0
      Norway
      Most emergency operations were performed for acute thrombosis and/or embolism, but 27 patients (1.8%) were operated on for rupture (six in Australia, 11 in Norway, and 10 in Sweden).
      18815180.33719.7
      New Zealand936064.53335.5
      Sweden
      Most emergency operations were performed for acute thrombosis and/or embolism, but 27 patients (1.8%) were operated on for rupture (six in Australia, 11 in Norway, and 10 in Sweden).
      49537074.712525.3
      Switzerland874248.34551.7
      All1,4711,05972.041228.0
      Note.
      a Most emergency operations were performed for acute thrombosis and/or embolism, but 27 patients (1.8%) were operated on for rupture (six in Australia, 11 in Norway, and 10 in Sweden).
      Endovascular repair was performed in 326 patients 22.2% (endovascular only in 307, hybrid operations in 19) (Table 5). The proportion of endovascular repair varied considerably from 34.7% in Australia to zero in Switzerland, Finland, and Iceland (p < .0001).
      Table 5The proportion of open and endovascular surgery for popliteal artery aneurysm in the different countries studied.
      CountryAll repairsOpen repair (n)Endovascular repair (n)Endovascular repair (%)
      Australia44128815334.7
      Finland (Helsinki)585800.0
      Hungary
      Sixteen hybrid operations in Sweden and three in Hungary were considered endovascular in this analysis.
      1039765.8
      Iceland6600.0
      Norway188171179.0
      New Zealand938944.3
      Sweden
      Sixteen hybrid operations in Sweden and three in Hungary were considered endovascular in this analysis.
      49534914629.5
      Switzerland878700.0
      All1,4711,14532622.2
      Note.
      a Sixteen hybrid operations in Sweden and three in Hungary were considered endovascular in this analysis.
      The choice of technique was also dependent on the indication. Endovascular technique was performed in only 12.2% of those operated on for emergency thrombosis compared with 24.1% of the elective cases (p < .0001). Of the 19 hybrid cases, 15 (79%) were performed for emergency thrombosis. Four of the 18 patients treated for rupture (22%) were operated on with an endovascular technique. There was a higher proportion of endovascular repair among women (34.4%) than among men (21.6%) (p = .031). Among patients ≥80 years of age, however, a higher proportion was treated with endovascular repair among men (39.6%) compared with women (25.0%), p = .031.
      All countries except Hungary registered the graft used during open repair. Among the 988 patients, 862 (87.2%) were operated on with a vein, 116 with a synthetic graft (11.7%), and 10 (1%) with a composite graft. The only country that registered the diameter of the PAs was Norway. The median diameter was 30 mm (range 10–90 mm), and only 3/168 patients (1.8%) had a diameter <15 mm.
      The inflow and outflow anatomy was available in 79.5% and 80.3% of the procedures. The femoral artery dominated (51.4%), followed by the popliteal artery (24.8%), and other inflow, such as a graft in 2.9%. The outflow vessel was most frequently the popliteal artery below the knee (58.7%), followed by a crural vessel (15.5%), the popliteal artery above the knee (4.6%), and a pedal vessel (0.3%).
      Only three of the countries registered the type of open surgical approach: Finland, Norway (Bergen County), and New Zealand. Among the 169 patients operated on in those countries, 145 (85.8%) were operated on with an open medial approach, 15 (8.9%) with an open posterior approach, and nine (5.3%) with endoPA repair.
      Sixty-five cases of thrombolysis were registered: 56 from Sweden, five from Norway, three from Finland, and one from Hungary. It was impossible, however, to distinguish if those were pre- or perioperative procedures, and many preoperative thrombolysis procedures may have been registered as separate procedures.
      The amputation rates in the participating countries are given in Table 4. The frequencies of major complications, including death and amputation, were difficult to compare between countries, as some countries only reported events during the first hospitalisation episode and others at follow-up 30 days after surgery. Overall, postoperative haemorrhage was registered in 61/1109 (5.5%), compartment syndrome in 13/782 (1.7%), and other wound complications in 129/1115 (11.6%). Acute coronary events were registered in 10/1108 (0.9%) and stroke in 5/853 (0.6%). One year follow-up data could be provided by few of the registries, and even in those was not complete. In Swedvasc, for instance, 2/3 of the patients had 1 year follow-up data. We therefore decided not to analyse those data. When comparing the three countries that had a high proportion of emergency repair (Finland, Hungary, and Switzerland), they had an amputation rate of 3.8% (9/239) compared to the remaining countries, which reported an amputation rate of 1.6% (20/1232; p = .040).
      The overall major amputation rate was 2.0%. It differed depending on indication with amputation occurring in 6.5% after emergency procedures for thrombosis. It also differed depending on surgical technique: 1.0% after endovascular, 1.8% after open, and 26.3% after hybrid repair (p < .0001). The mortality difference between endovascular and open technique was not significant. Ten patients died (0.7%) within 30 days or within the hospital stay, depending on which registry the patients were registered in. Mortality was 0.1% after elective surgery, 1.6% after emergency procedures for thrombosis, and 11.1% after the 27 procedures for rupture.

      Discussion

      To our knowledge, this is the first attempt to perform a multinational epidemiological overview of the current treatment of PA. The investigation is warranted, given the background of increasing numbers of procedures, and by the introduction of endovascular techniques. The number of operations per million inhabitants per year varied considerably between countries—the difference between Hungary and Sweden was more than fivefold (Table 1). Is this variability a result of differences in prevalence of disease, different diagnostic activity, or perhaps differences in indications for treatment of identified patients? Unfortunately, the database does not contain information to answer those important questions with certainty, but there are some possible explanations that may be discussed. We know from AAA screening studies in Sweden
      • Wanhainen A.
      • Björck M.
      The Swedish experience of screening for abdominal aortic aneurysm.
      • Svensjö S.
      • Björck M.
      • Gürtelschmid M.
      • Djavani Gidlund K.
      • Hellberg A.
      • Wanhainen A.
      Low prevalence of abdominal aortic aneurysm among 65-year old Swedish men indicates a change in the epidemiology of the disease.
      and the UK,
      • Conway A.M.
      • Malkawi A.H.
      • Hinchliffe R.J.
      • Holt P.J.
      • Murray S.
      • Thompson M.M.
      • et al.
      First-year results of a national abdominal aortic aneurysm. screening programme in a single centre.
      • Davis M.
      • Harris M.
      • Earnshaw J.J.
      Implementation of National Health Service abdominal aortic aneurysm screening program in England.
      as well as from epidemiological data on AAA rupture and death in Australia
      • Norman P.E.
      • Spilsbury K.
      • Semmens J.B.
      Falling rates of hospitalization and mortality from abdominal aortic aneurysms in Australia.
      and New Zealand
      • Sandiford P.
      • Mosquera D.
      • Bramley D.
      Trends in incidence and mortality from abdominal aortic aneurysm in New Zealand.
      that the prevalence of AAA is falling in many of the countries included in this investigation. This fall in AAA prevalence is thought to be explained mainly by falling smoking rates.
      • Svensjö S.
      • Björck M.
      • Gürtelschmid M.
      • Djavani Gidlund K.
      • Hellberg A.
      • Wanhainen A.
      Low prevalence of abdominal aortic aneurysm among 65-year old Swedish men indicates a change in the epidemiology of the disease.
      • Davis M.
      • Harris M.
      • Earnshaw J.J.
      Implementation of National Health Service abdominal aortic aneurysm screening program in England.
      There is a very strong association between PA and smoking and the coexistence of AAA. As a consequence, one would expect a decrease in the incidence of PA repair, but the opposite is found in Sweden. In a previous investigation from the same Swedvasc registry 1994–2001 the incidence of PA repair was only 8.3 per million person years
      • Ravn H.
      • Bergqvist D.
      • Björck M.
      Nationwide study of the outcome of popliteal artery aneurysms treated surgically.
      compared with 17.6 during 2009–2011—an increase of 112%.
      The increase in prevalence observed in Sweden could be a result of an increased awareness of the association between AAA and PA,
      • Ravn H.
      • Wanhainen A.
      • Bjorck M.
      Risk of new aneurysms after surgery for popliteal artery aneurysm.
      in combination with an increased detection rate of AAA in the population by screening. The screening programme in Sweden was initiated in 2006,
      • Wanhainen A.
      • Björck M.
      The Swedish experience of screening for abdominal aortic aneurysm.
      and many of the screening detected AAA patients were probably screened for PA with ultrasound, as this is a routine in most Swedish hospitals, but not in the other countries participating in this investigation. There may also be national differences in how patients with acute limb ischaemia are assessed. If no ultrasound examination is performed in a patient with an acute thrombosis of the popliteal artery, an underlying PA may not be detected.
      The great differences in disease prevalence may also be explained by ethnicity and hereditary factors. It has been shown in AAA disease that there is a strong interaction between heredity and environment.
      • Björck M.
      • Wanhainen A.
      Pathophysiology of AAA: heredity vs environment.
      Although there are less data on patients with PA, we have reasons to believe that the same interaction is present in these patients, who often have concomitant AAA.
      The main risk factors for AAA, smoking, and male sex, dominate even more in the PA population. Svensjö et al.
      • Svensjö S.
      • Björck M.
      • Gürtelschmid M.
      • Djavani Gidlund K.
      • Hellberg A.
      • Wanhainen A.
      Low prevalence of abdominal aortic aneurysm among 65-year old Swedish men indicates a change in the epidemiology of the disease.
      reported that 33% of 373 65-year-old men screened were smokers compared to 44% in this cohort of patients with PA. In another report from Vascunet, Mani et al.
      • Mani K.
      • Lees T.
      • Beiles B.
      • Jensen L.P.
      • Venermo M.
      • Simo G.
      • et al.
      Treatment of abdominal aortic aneurysm in nine countries 2005–2009: a Vascunet report.
      reported that 13.3% of patients after intact AAA repair and 16.2% after ruptured AAA repair were women compared to only 4.6% in this cohort of patients with PA.
      Ravn et al.
      • Ravn H.
      • Wanhainen A.
      • Björck M.
      Surgical technique and long-term results after popliteal artery aneurysm repair. Results from 717 operated legs.
      reported that late expansion was common after open PA repair, 33% after a mean of 7.2 years, when the medial approach was used—a complication similar to type II endoleak after endovascular aneurysm repair (EVAR). This complication, that was virtually non-existent after an operation with a posterior approach, was associated with symptoms in most patients, and some even required reoperation. Unfortunately, the choice of surgical access in open surgery was reported from only three countries in this investigation, but the medial approach dominated with 85%. Several of the registries are now adding this variable to their databases, so we will know in the future if a shift in the choice of surgical access route takes place.
      This study focused on the definitive repair of PA. Unfortunately, we were unable to identify all the patients who first underwent intra-arterial thrombolysis, followed by definitive open or endovascular repair, and to distinguish those from patients who underwent perioperative thrombolysis. One of the effects of this kind of exercise, merging data from different registries, is that variables are added when missing and amended when necessary, thus facilitating future research. A variable indicating preoperative thrombolysis (yes/no) was added to the Swedvasc registry when registering carotid procedures 2 years ago, and is now being added also to the PA module, and if more countries join a future analysis of this data will turn possible.
      The effect of preoperative thrombolysis on short- and long-term results was not possible to analyse in this database, the reason being that this intervention could be registered either as an independent operation, or as a part of the open or endovascular procedure aimed at repairing the PA. This limitation of the participating registries was highlighted by this project, and several of the registries are preparing to revise their registration to enable such an analysis in the future. This is, in fact, one of the most important results of the Vascunet collaboration, that is, that the registries are adapted and amended as a result of previous investigations.
      • Galiñanes E.L.
      • Dombrovskiy V.Y.
      • Graham A.M.
      • Vogel T.R.
      Endovascular versus open repair of popliteal artery aneurysms; outcomes in the US medicare population.
      • Björck M.
      • Gibbons C.
      • Jensen L.P.
      • Laustsen J.
      • Lees T.
      • Moreno-Carriles R.
      • et al.
      Vascular registries join and create the common European dataset on AAA surgery.
      • Mani K.
      • Lees T.
      • Beiles B.
      • Jensen L.P.
      • Venermo M.
      • Simo G.
      • et al.
      Treatment of abdominal aortic aneurysm in nine countries 2005–2009: a Vascunet report.
      • Menyhei G.
      • Björck M.
      • Beiles B.
      • Halbakken E.
      • Jensen L.P.
      • Lees T.
      • et al.
      Outcome following carotid endarterectomy: lessons learned from a large international vascular registry.
      • Vikatmaa P.
      • Mitchell D.
      • Jensen L.P.
      • Beiles B.
      • Björck M.
      • Halbakken E.
      • et al.
      Variation in clinical practice in carotid surgery in 9 countries 2005–2010. Lessons from VASCUNET and recommendations for the future of national clinical audit.
      • Lees T.
      • Troëng T.
      • Thomson I.A.
      • Menyhei G.
      • Simo G.
      • Beiles B.
      • et al.
      International variations in infrainguinal bypass surgery – a VASCUNET report.
      Among the most interesting observations are the great differences between countries in indications for treatment and in frequency of endovascular repair. If we exclude Iceland, which is a small country in which only six patients were operated on, the proportion of elective repairs varied between 86% in Australia and only 26% in Hungary (Table 3). These differences probably reflect both the level of diagnostic activity and the therapeutic tradition, whether to treat asymptomatic patients or not, including the diameter threshold and if the presence of thrombosis in smaller aneurysms is considered an indication for surgery. Unfortunately, we only have information for the diameter of the PA from one country (Norway). That country, however, had one of the highest proportions of elective repairs (80%) and yet only 2% had a diameter <15 mm. It will be interesting to perform a study in the future to assess whether the countries that presently have a predominance of emergency repair (Hungary, Finland, and Switzerland) have a higher proportion of elective repairs. As expected, the patients in these countries having a high proportion of emergency repair, also suffered a significantly higher risk of amputation, thus identifying an area of quality improvement.
      Similar differences between countries were identified regarding the proportion of endovascular repair (Table 4). The highest proportion of endovascular repairs was found in Australia and Sweden. Countries with a high proportion of endovascular repair often also had a high incidence of operations per million inhabitants (Tables 2 and 3), and we have speculated that this trend might be explained by operating on older patients with endovascular techniques rather than open surgery. This does not seem to be the case, however: Australia has a median age of 74 years, but in Sweden the median is only 69 years, compared with the average of 70 years. It seems that the choice of surgical technique is more a result of surgical tradition than differences in case mix. Interestingly, the overall proportion of endovascular repairs in the studied countries (22.2%) was quite similar to that reported from the USA in 2007 (23.6%).
      • Galiñanes E.L.
      • Dombrovskiy V.Y.
      • Graham A.M.
      • Vogel T.R.
      Endovascular versus open repair of popliteal artery aneurysms; outcomes in the US medicare population.
      These trends are similar to those in intact AAA repair, where we previously reported that Finland and Hungary had the lowest, and Australia and Sweden the highest, proportion of EVAR.
      • Mani K.
      • Lees T.
      • Beiles B.
      • Jensen L.P.
      • Venermo M.
      • Simo G.
      • et al.
      Treatment of abdominal aortic aneurysm in nine countries 2005–2009: a Vascunet report.
      While we have multiple randomised trials guiding us in the choice of open or endovascular repair of AAA,
      • EVAR Trial Participants
      Endovascular aneurysm repair versus open repair in patients with abdominal aortic aneurysm (EVAR trial 1): randomised controlled trial.
      • Blankensteijn J.D.
      • de Jong S.E.
      • Prinssen M.
      • van der Ham A.C.
      • Buth J.
      • van Sterkenburg S.M.
      • et al.
      Two-year outcomes after conventional or endovascular repair of abdominal aortic aneurysms.
      • Powell J.T.
      • Brown L.C.
      • Forbes J.F.
      • Fowkes F.G.
      • Greenhalgh R.M.
      • Ruckley C.V.
      • et al.
      Final 12-year follow-up of surgery versus surveillance in the UK Small Aneurysm Trial.
      • Lederle F.A.
      • Wilson S.E.
      • Johnson G.R.
      • Reinke D.B.
      • Littooy F.N.
      • Acher C.W.
      • et al.
      Immediate repair compared with surveillance of small abdominal aortic aneurysms.
      there are no similar data on how to treat PA, yet the trends are similar. Thus, it seems that therapeutic tradition rather than evidence guides vascular surgeons. A randomised trial comparing the techniques is certainly warranted. That could also supply us with long-term follow-up, which is crucial to evaluate the two methods. In this investigation we had only short term follow-up, which showed no difference in results. As one of the concerns regarding the new endovascular technique is durability, adding long-term follow-up in the registry databases is of utmost importance.
      A potential limitation in all registry data is the risk of selection bias due to insufficient validity. Several of these participating registries have been extensively validated, however (D. Bergqvist, M. Björck, T. Lees, G. Menyhei, submitted).
      • Troeng T.
      • Malmstedt J.
      • Bjorck M.
      External validation of the Swedvasc registry: a first-time individual cross-matching with the unique personal identity number.
      • Beiles C.B.
      • Bourke B.
      • Thomson I.
      Results from the Australasian Vascular Surgical Audit: the inaugural year.
      • Kantonen I.
      • Lepäntalo M.
      • Salenius J.P.
      • Forsström E.
      • Hakkarainen T.
      • Huusari H.
      • et al.
      Auditing a nationwide vascular registry – the 4-year Finnvasc experience. Finnvasc Study Group.
      The Swedvasc was specifically validated for PA operations. Among 717 primary operations for PA, 146 were found to have bilateral operations when the case records were scrutinised; of those, 141 (96.6%) had been registered.
      • Ravn H.
      • Bergqvist D.
      • Björck M.
      Nationwide study of the outcome of popliteal artery aneurysms treated surgically.
      When the variables to be collected were decided upon (Table 1), decisions were based on those available in most of the registries. This analysis has shown that the registries need to be revised and collect more precise data on pathology, indication, treatment and outcome in the future, and those variables given in Table 6.
      Table 6Suggested variables to be added to the vascular registries.
      Pathology/indication
      Diameter of the aneurysmmm
      Thrombosis in the aneurysmYes/no
      Number of run-off vessels0–3
      Treatment
      Preoperative thrombolysisYes/no
      Perioperative thrombolysisYes/no
      Approach during open repairMedial/posterior
      FasciotomyYes/no
      Outcome at 30 days and 1 year
      PatencyYes/no
      AmputationYes/no
      SymptomsClaudication/ulcer/gangrene

      Conclusions

      In this analysis of contemporary PA repair in eight countries, a great variability in incidence of operations, indications for surgery, and choice of surgical technique was found. Those differences seem to be more a result of surgical tradition than of differences in case mix. The participating registries need to revise their variables to improve recording of the patients who undergo preoperative thrombolysis prior to definite surgical repair, and to introduce at least 1 year of follow-up in order to evaluate medium-term results.

      Conflict of Interest

      None.

      Funding

      None.

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