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Endovascular and Open Approaches to Non-thrombosed Popliteal Aneurysm Repair: A Meta-analysis
Eur J Vasc Endovasc Surg (2008) 36, 96e100
REVIEW
Endovascular and Open Approaches to Non-thrombosed Popliteal Aneurysm Repair: A Meta-analysis R.E. Lovegrove, M. Javid, T.R. Magee, R.B. Galland* Department of General Surgery, Royal Berkshire Hospital, Reading, UK Submitted 23 October 2007; accepted 4 February 2008 Available online 8 April 2008
KEYWORDS Popliteal artery; Aneurysm; Meta-analysis; Endovascular; Comparative
Abstract Objective: Endovascular repair of popliteal artery aneurysms is a relatively new technique that is still undergoing evaluation. The aim of this study was to compare outcomes following open and endovascular approaches. Methods: All published studies comparing outcomes following open and endovascular popliteal aneurysm were included. Endpoints included operative duration, length of stay, and postoperative complications including short-term patency rates. Outcomes were combined using a random-effects meta-analytical technique and differences assessed using odds ratios (OR), weighted mean difference (WMD) and log hazards ratio (HR). Results: Three studies comprising 141 patients (37 endovascular; 104 open) were included. No significant differences in patient characteristics were seen. Operative duration was significantly longer for endovascular repair (WMD 120 minutes, p < 0.001). Thirty day graft thrombosis (OR 5.05, p Z 0.06) and reintervention (OR 18.80, p Z 0.03) were more likely following endovascular repairs. Postoperative length of stay was shorter in the endovascular group (WMD e 3.9 days, p < 0.001). There was no significant difference in long-term primary patency rates (HR 1.70, p Z 0.53). Conclusions: Endovascular repair of popliteal artery aneurysms offers similar medium-term benefits as an open repair. However, short-term graft thrombosis and reintervention rates are significantly greater. With the current technology it is difficult to justify endovascular treatment of popliteal aneurysms. ª 2008 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
* Corresponding author. Mr. R. B. Galland, Consultant Vascular Surgeon, Royal Berkshire Hospital, London Road, Reading, Berkshire, RG1 5AN. Tel.: þ118 322 7419; fax: þ118 322 7881. E-mail address: [email protected] (R.B. Galland). 1078-5884/$34 ª 2008 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ejvs.2008.02.002
Non-thrombosed Popliteal Aneurysm Repair
Introduction Management of popliteal aneurysms (PA) has evolved from inducing thrombosis by compression or ligation; obliteration of the aneurysm, with or without sympathectomy; to preserving circulation whilst excluding the aneurysm.1 The commonest procedure carried out today is ligation, combined with bypass by a medial approach. The conduit of choice is autologous vein.2 This technique has recently been challenged. Some reports have suggested that the popliteal aneurysm can develop or retain flow following ligation in up to one third of cases.3e5 Significant symptoms have been described in up to one fifth of cases.4e6 These findings have not been confirmed by others.7 An open posterior approach, whereby the aneurysm is opened and an interposition graft inserted, is an alternative which overcomes these problems.8 Endovascular repair of abdominal aortic aneurysms is gradually gaining acceptance and produces good short and medium-term results compared with a conventional open repair.9 There is much less evidence to support the use of endovascular stenting for peripheral artery aneurysms. The first report of popliteal artery stenting was in 1994.10 Palmaz stents covered with a polytetrafluoroethylene (PTFE) graft were used. Since then there have been reports suggesting that in selected cases endovascular repair can produce equivalent results to open repair. The aim of this paper is to compare endovascular with open repair of nonthrombosed popliteal aneurysms based on current evidence.
Methods Study selection The literature was searched using PubMed and Medline databases for published studies comparing outcomes between open and endovascular approaches to the treatment of popliteal aneurysms. The following MeSH search terms were used: ‘‘popliteal artery’’, ‘‘aneurysm’’, ‘‘vascular surgical procedures’’, ‘‘stents’’, ‘‘blood vessel prosthesis implantation’’ and ‘‘randomized controlled trials’’. In addition the following keywords were used: ‘‘endovascular’’, and ‘‘comparative’’. These terms were used in various combinations together with use of the ‘‘related articles’’ function in order to maximise the search. No restrictions on language of publication were made and references from obtained articles were hand searched. The date of the last search was 31 July 2007.
97 unable to be extracted from the published report. Outcomes where there were no events for either the open or endovascular group were excluded from the meta-analysis of that outcome, but were taken into account when considering the overall sample size for the outcome.
Outcomes of interest Outcomes of interest were considered in two areas: Operative parameters: These consisted of operative time recorded in minutes, recorded blood loss in millilitres (ml), and postoperative length of stay recorded in days. Complications: These consisted of all complications occurring within 30 days of operation, or in the case of graft surveillance, during recorded follow up. Primary patency rates were defined as the time from surgery to graft or stent occlusion, and were derived from published KaplanMeier plots. Reintervention rates were also recorded.
Statistical analysis Meta-analysis was performed in line with recommendations from the Cochrane Collaboration the Quality of Reporting of Meta-analyses (QUORUM) guidelines.11,12 The effect measures estimated were odds ratio (OR) for dichotomous data and weighted mean difference (WMD) for continuous data, both reported with 95% confidence intervals (CI).13 The analysis was undertaken by comparing endovascular with open surgery with an odds ratio of more than 1 denoting that an event was more common following endovascular surgery. Studies that contained a zero in one cell for the number of events of interest in one of the two groups resulted in problems with the computation of ratio measurement. To overcome this problem the Haldane correction was applied, whereby a value of 0.5 was added in both groups from that particular study.14 Long-term graft patency rates were extracted from published hazards ratios (HR) and Kaplan-Meier survival curves using the techniques described by Parmar et al.15 For categoric variables the odds ratios were combined with the ManteleHaenszel Chi-squared method using a ‘‘random effect’’ meta-analytical technique.16 In a random effect model it is assumed that there is variation between studies and the calculated odds ratio thus has a more conservative value.17,18 In surgical research, metaanalysis using the random effect model is preferable particularly because patients that are operated on in different centres have varying risk profiles and selection criteria for
Inclusion criteria Included studies had to compare outcomes between open and endovascular approaches to popliteal aneurysm repair and report on at least one of the outcome measures described below. Studies assessing outcome following open or endovascular approaches to thrombosed popliteal artery aneurysms were not excluded from the literature search.
Exclusion criteria Studies were excluded from further analysis if they did not report outcomes in a comparable fashion or data were
Table 1
Characteristics of the included studies
Study
Antonello Curi21 Stone26
No. Cases 20
Endo
Open
Dates of Study
15 15 7
15 41 48
1999e2003 2000e2006 1995e2004
Matching Criteria 1,2,3,5,6,7,8 1,5,6,7,8 4
Matching criteria: 1 Z Gender, 2 Z Age, 3 Z Aneurysm diameter, 4 Z Symptomatic presentation, 5 Z Smoking status, 6 Z Diabetes, 7 Z Hypertension, 8 Z Bilateral popliteal aneurysms.
98 Table 2
R.E. Lovegrove et al. Characteristics of patients undergoing open or endovascular popliteal artery aneurysm repair
Characteristic
No. Studies
Mean age Male gender Hypertension Diabetes Cardiac disease Pulmonary disease Smoking Aneurysm diameter (mm)
2 3 2 2 2 2 2 1
No. Patients Endo
Open
30 37 30 30 30 30 30 15
56 104 56 56 56 56 56 15
OR/WMD* (95% CI)
2.94 1.94 0.59 0.58 1.32 0.41 0.45 1.1
(5.83, 11.72)* (0.36, 10.37) (0.22, 1.54) (0.16, 2.13) (0.51, 3.44) (0.10, 1.76) (0.10, 1.76) (8.6, 10.8)*
p-value
HG c2
HG p-value
0.510 0.440 0.280 0.410 0.560 0.230 0.100 0.820
9.42 0.46 0.27 0.41 0.00 0.36 0.74 e
0.002 0.500 0.600 0.520 0.950 0.550 0.390 e
OR e Odds ratio. WMD e Weighted mean difference. CI e Confidence interval. HG e Heterogeneity. P values in bold denote statistical significance at the 5% level. * Outcomes given as WMD.
each surgical technique. For studies that presented continuous data as mean and range values, the standard deviation (SD) was calculated using statistical algorithms and checked using ‘‘bootstrap’’ resampling techniques. Thus all continuous data were standardized for the analysis. Heterogeneity was quantitatively assessed by calculation of Chi square statistic for a given outcome and graphical exploration with funnel plots was used to evaluate publication bias.13,19 Analysis was conducted using Review Manager Version 4.3 (The Cochrane Collaboration, Software Update, Oxford, UK).
Results Studies selected The literature search identified eight studies for potential inclusion in the analysis.2,20e26 five of these were subsequently excluded as there were no extractable comparative
Table 3
results between the open and endovascular approaches.2,22e25 The remaining three20,21,26 studies, comprising 141 patients (37 endovascular and 104 open), were included in the analysis. One study used the Hemobahn graft,20 one Viabahn endografts,21 and the third used the Wall graft in five patients and Viabahn in two patients.26 There were no studies assessing outcome of thrombosed popliteal artery aneurysms that met the inclusion criteria.
Patient characteristics There were 133 (94.3%) men with no significant differences between the open and endovascular groups (Tables 1 and 2). Mean age at intervention and mean aneurysm diameter did not differ significantly between the two groups. Hypertension was noted in 66%, cardiac disease in 46%, pulmonary disease in 17% and diabetes in 20% with no statistically significant differences between the two groups. A smoking history was noted in 66% of patients. In one study,21 bilateral popliteal aneurysms were recorded
Operative details and postoperative complications following endovascular and open popliteal aneurysm repair
Outcome
Operative time (mins) Length of stay (days) 30 Day graft thrombosis 30 Day reintervention Long-term graft patency
No. Studies
1 2 2 1 2
No. Patients Endo
Open
15 30 22 7 30
15 56 63 48 56
OR e Odds ratio. WMD e Weighted mean difference. HR e Hazard ratio. CI e Confidence interval. HG e Heterogeneity. P values in bold denote statistical significance at the 5% level. * Outcomes given as WMD. þ Outcomes given as HR.
OR/WMD*/HRþ (95% CI)
119.9 3.9 5.05 18.80 1.70
(102.1, 137.7)* (4.3, 3.5)* (0.91, 28.11) (1.44, 245.99) (0.33, 8.75)þ
p-value
HG c2
HG p-value
<0.001 <0.001 0.060 0.030 0.530
e 1.29 0.11 e 0.06
e 0.260 0.740 e 0.810
Non-thrombosed Popliteal Aneurysm Repair
Figure 1
99
Forest plot illustrating long-term graft patency following open and endovascular popliteal aneurysm repair
in 42 (63.6%) of 66 patients. One study21 provided details of distal run-off in the open and endovascular groups, with patients having 1, 2 or 3 vessel run-off in approximately 33% of cases in both groups.
Outcomes following open or endovascular popliteal aneurysm repair Duration of the interventional procedure was significantly longer for endovascular interventions than for open repair [WMD 119.9 minutes (95% CI 102.1e137.7), p < 0.001] (Table 3). Postoperative length of stay was significantly shorter following endovascular procedures when compared with open [WMD e 3.9 days (95% CI e 4.3e3.5), p < 0.001]. The incidence of 30 day graft thrombosis and reintervention rates were significantly greater following endovascular repair of popliteal aneurysms. However, medium-term graft patency did not differ significantly between the two groups (Fig. 1).
Discussion This meta-analysis has shown no difference in mediumterm patency comparing open with endovascular treatment of popliteal aneurysms. Patency following ligation and bypass is 70%e94% at five years.27 Similar results are obtained when an open posterior approach is used.28 In a series of 57 PA undergoing endovascular repair from 1998e 2004 a two year primary patency of 77% was achieved.29 Medium-term patency of the 112 PA in our study was 1.70 times greater following open surgery when compared with endovascular approaches. Approximately 30% to 50% of popliteal artery aneurysms are asymptomatic at the time of presentation,3,30 although this can be as high as 80% in some series.31 The avoidance of complications is therefore paramount. Complications following elective open repair of popliteal aneurysms are uncommon. Thirty day mortality is less than 1%, and limb loss less than 2%.27 The commonest postoperative problems involve the surgical wound, occurring in about 5% of cases.32 Both local and systemic complications are greater in patients undergoing open repair of popliteal aneurysms for acute ischaemia.27,32 Early graft failure is uncommon. By contrast, in this study we found that 30 day graft thrombosis was significantly higher in patients undergoing endovascular repair. Similarly, 30 day reintervention was also greater in this group of patients. There were 13 early and late stent-related complications in nine patients from
a group of 67 popliteal artery aneurysms.29 These included migration, with or without endoleaks, stenosis and stent disruption. Endoleak has been described in 20% of endovascular popliteal artery aneurysm repairs at a mean follow up of 16 months.21 It is possible that the included studies may represent pilot studies assessing the feasibility of endovascular repair of popliteal aneurysm. This may go some way to explaining the significantly longer operative time seen in the endovascular group, although this outcome was discussed in only one study. In the absence of further studies from centres with established endovascular practices being available the effect of endovascular repair on operative time needs to be interpreted with some caution. The only advantage which we have demonstrated for endovascular repair is a shorter length of stay in hospital. This needs to be balanced against the greater number of complications seen in these patients. With the technology currently available it is difficult to justify endovascular repair for patent popliteal aneurysms. Future advances in technology and the overcoming of any learning curves may lead to improvements in outcome following endovascular repair of popliteal artery aneurysms and these would need to be reassessed at the appropriate time.
References 1 Galland RB. History of the management of popliteal aneurysms. Eur J Vasc Endovasc Surg 2008;35:466e72. 2 Ravn H, Bergqvist D, Bjorck M. Nationwide study of the outcome of popliteal artery aneurysms treated surgically. Br J Surg 2007; 94:970e7. 3 Ebaugh JL, Morasch MD, Matsumura JS, Eskandari MK, Meadows WS, Pearce WH. Fate of excluded popliteal artery aneurysms. J Vasc Surg 2003;37:954e9. 4 Jones 3rd WT, Hagino RT, Chiou AC, Decaprio JD, Franklin KS, Kashyap VS. Graft patency is not the only clinical predictor of success after exclusion and bypass of popliteal artery aneurysms. J Vasc Surg 2003;37:392e8. 5 Kirkpatrick UJ, McWilliams RG, Martin J, Brennan JA, GillingSmith GL, Harris PL. Late complications after ligation and bypass for popliteal aneurysm. Br J Surg 2004;91:174e7. 6 Mehta M, Champagne B, Darling 3rd RC, Roddy SP, Kreienberg PB, Ozsvath KJ, et al. Outcome of popliteal artery aneurysms after exclusion and bypass: significance of residual patent branches mimicking type II endoleaks. J Vasc Surg 2004;40:886e90. 7 Box B, Adamson M, Magee TR, Galland RB. Outcome following bypass, and proximal and distal ligation of popliteal aneurysms. Br J Surg 2007;94:179e82.
100 8 Beseth BD, Moore WS. The posterior approach for repair of popliteal artery aneurysms. J Vasc Surg 2006;43:940e4. 9 Lovegrove RE, Javid M, Magee TR, Galland RB. Open and endovascular aortic aneurysm repair: a meta-analysis of 21,178 patients. Br J Surg, in press. 10 Marin ML, Veith FJ, Panetta TF, Cynamon J, Bakal CW, Suggs WD, et al. Transfemoral endoluminal stented graft repair of a popliteal artery aneurysm. J Vasc Surg 1994;19:754e7. 11 Clarke M, Horton R. Bringing it all together: Lancet-Cochrane collaborate on systematic reviews. Lancet 2001;357:1728. 12 Stroup DF, Berlin JA, Morton SC, Olkin I, Williamson GD, Rennie D, et al. Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group. JAMA 2000; 283:2008e12. 13 Egger M, Davey Smith G, Schneider M, Minder C. Bias in metaanalysis detected by a simple, graphical test. BMJ 1997;315: 629e34. 14 Haldane JB. The estimation and significance of the logarithm of a ratio of frequencies. Ann Hum Genet 1956;20:309e11. 15 Parmar MK, Torri V, Stewart L. Extracting summary statistics to perform meta-analyses of the published literature for survival endpoints. Stat Med 1998;17:2815e34. 16 Mantel N, Haenszel W. Statistical aspects of the analysis of data from retrospective studies of disease. J Natl Cancer Inst 1959; 22:719e48. 17 DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials 1986;7:177e88. 18 Sterne JA, Davey Smith G. Sifting the evidence-what’s wrong with significance tests? BMJ 2001;322:226e31. 19 Egger M, Smith GD. Misleading meta-analysis. BMJ 1995;311: 753e4. 20 Antonello M, Frigatti P, Battocchio P, Lepidi S, Cognolato D, Dall’Antonia A, et al. Open repair versus endovascular treatment for asymptomatic popliteal artery aneurysm: results of a prospective randomized study. J Vasc Surg 2005;42:185e93. 21 Curi MA, Geraghty PJ, Merino OA, Veeraswamy RK, Rubin BG, Sanchez LA, et al. Mid-term outcomes of endovascular popliteal artery aneurysm repair. J Vasc Surg 2007;45:505e10.
R.E. Lovegrove et al. 22 Mohan IV, Bray PJ, Harris JP, May J, Stephen MS, Bray AE, et al. Endovascular popliteal aneurysm repair: are the results comparable to open surgery? Eur J Vasc Endovasc Surg 2006;32:149e54. 23 Pulli R, Dorigo W, Troisi N, Innocenti AA, Pratesi G, Azas L, et al. Surgical management of popliteal artery aneurysms: which factors affect outcomes? J Vasc Surg 2006;43:481e7. 24 Ravn H, Wanhainen A, Bjorck M. Surgical technique and longterm results after popliteal artery aneurysm repair: results from 717 legs. J Vasc Surg 2007;46:236e43. 25 Rosenthal D, Matsuura JH, Clark MD, Kirby LB, Knoepp LF. Popliteal artery aneurysms: is endovascular reconstruction durable? J Endovasc Ther 2000;7:394e8. 26 Stone PA, Armstrong PA, Bandyk DF, Keeling WB, Flaherty SK, Shames ML, et al. The value of duplex surveillance after open and endovascular popliteal aneurysm repair. J Vasc Surg 2005; 41:936e41. 27 Michaels JA, Galland RB. Management of asymptomatic popliteal aneurysms: the use of a Markov decision tree to determine the criteria for a conservative approach. Eur J Vasc Surg 1993;7: 136e43. 28 Kropman RH, van Santvoort HC, Teijink J, van de Pavoordt HD, Belgers HJ, Moll FL, et al. The medial versus the posterior approach in the repair of popliteal artery aneurysms: a multicenter case-matched study. J Vasc Surg 2007;46:24e30. 29 Tielliu IF, Verhoeven EL, Zeebregts CJ, Prins TR, Span MM, van den Dungen JJ. Endovascular treatment of popliteal artery aneurysms: results of a prospective cohort study. J Vasc Surg 2005;41:561e7. 30 Laxdal E, Amundsen SR, Dregelid E, Pedersen G, Aune S. Surgical treatment of popliteal artery aneurysms. Scand J Surg 2004; 93:57e60. 31 Galland RB. Natural history and management of popliteal aneurysms. In: Galland RB, Magee TR, Lewis MH, editors. Topical Issues in Vascular Surgery. Kerala: Research Signpost; 2005. p. 91e101. 32 Huang Y, Gloviczki P, Noel AA, Sullivan TM, Kalra M, Gullerud RE, et al. Early complications and long-term outcome after open surgical treatment of popliteal artery aneurysms: is exclusion with saphenous vein bypass still the gold standard? J Vasc Surg 2007;45:706e13.
REVIEW
Endovascular and Open Approaches to Non-thrombosed Popliteal Aneurysm Repair: A Meta-analysis R.E. Lovegrove, M. Javid, T.R. Magee, R.B. Galland* Department of General Surgery, Royal Berkshire Hospital, Reading, UK Submitted 23 October 2007; accepted 4 February 2008 Available online 8 April 2008
KEYWORDS Popliteal artery; Aneurysm; Meta-analysis; Endovascular; Comparative
Abstract Objective: Endovascular repair of popliteal artery aneurysms is a relatively new technique that is still undergoing evaluation. The aim of this study was to compare outcomes following open and endovascular approaches. Methods: All published studies comparing outcomes following open and endovascular popliteal aneurysm were included. Endpoints included operative duration, length of stay, and postoperative complications including short-term patency rates. Outcomes were combined using a random-effects meta-analytical technique and differences assessed using odds ratios (OR), weighted mean difference (WMD) and log hazards ratio (HR). Results: Three studies comprising 141 patients (37 endovascular; 104 open) were included. No significant differences in patient characteristics were seen. Operative duration was significantly longer for endovascular repair (WMD 120 minutes, p < 0.001). Thirty day graft thrombosis (OR 5.05, p Z 0.06) and reintervention (OR 18.80, p Z 0.03) were more likely following endovascular repairs. Postoperative length of stay was shorter in the endovascular group (WMD e 3.9 days, p < 0.001). There was no significant difference in long-term primary patency rates (HR 1.70, p Z 0.53). Conclusions: Endovascular repair of popliteal artery aneurysms offers similar medium-term benefits as an open repair. However, short-term graft thrombosis and reintervention rates are significantly greater. With the current technology it is difficult to justify endovascular treatment of popliteal aneurysms. ª 2008 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
* Corresponding author. Mr. R. B. Galland, Consultant Vascular Surgeon, Royal Berkshire Hospital, London Road, Reading, Berkshire, RG1 5AN. Tel.: þ118 322 7419; fax: þ118 322 7881. E-mail address: [email protected] (R.B. Galland). 1078-5884/$34 ª 2008 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ejvs.2008.02.002
Non-thrombosed Popliteal Aneurysm Repair
Introduction Management of popliteal aneurysms (PA) has evolved from inducing thrombosis by compression or ligation; obliteration of the aneurysm, with or without sympathectomy; to preserving circulation whilst excluding the aneurysm.1 The commonest procedure carried out today is ligation, combined with bypass by a medial approach. The conduit of choice is autologous vein.2 This technique has recently been challenged. Some reports have suggested that the popliteal aneurysm can develop or retain flow following ligation in up to one third of cases.3e5 Significant symptoms have been described in up to one fifth of cases.4e6 These findings have not been confirmed by others.7 An open posterior approach, whereby the aneurysm is opened and an interposition graft inserted, is an alternative which overcomes these problems.8 Endovascular repair of abdominal aortic aneurysms is gradually gaining acceptance and produces good short and medium-term results compared with a conventional open repair.9 There is much less evidence to support the use of endovascular stenting for peripheral artery aneurysms. The first report of popliteal artery stenting was in 1994.10 Palmaz stents covered with a polytetrafluoroethylene (PTFE) graft were used. Since then there have been reports suggesting that in selected cases endovascular repair can produce equivalent results to open repair. The aim of this paper is to compare endovascular with open repair of nonthrombosed popliteal aneurysms based on current evidence.
Methods Study selection The literature was searched using PubMed and Medline databases for published studies comparing outcomes between open and endovascular approaches to the treatment of popliteal aneurysms. The following MeSH search terms were used: ‘‘popliteal artery’’, ‘‘aneurysm’’, ‘‘vascular surgical procedures’’, ‘‘stents’’, ‘‘blood vessel prosthesis implantation’’ and ‘‘randomized controlled trials’’. In addition the following keywords were used: ‘‘endovascular’’, and ‘‘comparative’’. These terms were used in various combinations together with use of the ‘‘related articles’’ function in order to maximise the search. No restrictions on language of publication were made and references from obtained articles were hand searched. The date of the last search was 31 July 2007.
97 unable to be extracted from the published report. Outcomes where there were no events for either the open or endovascular group were excluded from the meta-analysis of that outcome, but were taken into account when considering the overall sample size for the outcome.
Outcomes of interest Outcomes of interest were considered in two areas: Operative parameters: These consisted of operative time recorded in minutes, recorded blood loss in millilitres (ml), and postoperative length of stay recorded in days. Complications: These consisted of all complications occurring within 30 days of operation, or in the case of graft surveillance, during recorded follow up. Primary patency rates were defined as the time from surgery to graft or stent occlusion, and were derived from published KaplanMeier plots. Reintervention rates were also recorded.
Statistical analysis Meta-analysis was performed in line with recommendations from the Cochrane Collaboration the Quality of Reporting of Meta-analyses (QUORUM) guidelines.11,12 The effect measures estimated were odds ratio (OR) for dichotomous data and weighted mean difference (WMD) for continuous data, both reported with 95% confidence intervals (CI).13 The analysis was undertaken by comparing endovascular with open surgery with an odds ratio of more than 1 denoting that an event was more common following endovascular surgery. Studies that contained a zero in one cell for the number of events of interest in one of the two groups resulted in problems with the computation of ratio measurement. To overcome this problem the Haldane correction was applied, whereby a value of 0.5 was added in both groups from that particular study.14 Long-term graft patency rates were extracted from published hazards ratios (HR) and Kaplan-Meier survival curves using the techniques described by Parmar et al.15 For categoric variables the odds ratios were combined with the ManteleHaenszel Chi-squared method using a ‘‘random effect’’ meta-analytical technique.16 In a random effect model it is assumed that there is variation between studies and the calculated odds ratio thus has a more conservative value.17,18 In surgical research, metaanalysis using the random effect model is preferable particularly because patients that are operated on in different centres have varying risk profiles and selection criteria for
Inclusion criteria Included studies had to compare outcomes between open and endovascular approaches to popliteal aneurysm repair and report on at least one of the outcome measures described below. Studies assessing outcome following open or endovascular approaches to thrombosed popliteal artery aneurysms were not excluded from the literature search.
Exclusion criteria Studies were excluded from further analysis if they did not report outcomes in a comparable fashion or data were
Table 1
Characteristics of the included studies
Study
Antonello Curi21 Stone26
No. Cases 20
Endo
Open
Dates of Study
15 15 7
15 41 48
1999e2003 2000e2006 1995e2004
Matching Criteria 1,2,3,5,6,7,8 1,5,6,7,8 4
Matching criteria: 1 Z Gender, 2 Z Age, 3 Z Aneurysm diameter, 4 Z Symptomatic presentation, 5 Z Smoking status, 6 Z Diabetes, 7 Z Hypertension, 8 Z Bilateral popliteal aneurysms.
98 Table 2
R.E. Lovegrove et al. Characteristics of patients undergoing open or endovascular popliteal artery aneurysm repair
Characteristic
No. Studies
Mean age Male gender Hypertension Diabetes Cardiac disease Pulmonary disease Smoking Aneurysm diameter (mm)
2 3 2 2 2 2 2 1
No. Patients Endo
Open
30 37 30 30 30 30 30 15
56 104 56 56 56 56 56 15
OR/WMD* (95% CI)
2.94 1.94 0.59 0.58 1.32 0.41 0.45 1.1
(5.83, 11.72)* (0.36, 10.37) (0.22, 1.54) (0.16, 2.13) (0.51, 3.44) (0.10, 1.76) (0.10, 1.76) (8.6, 10.8)*
p-value
HG c2
HG p-value
0.510 0.440 0.280 0.410 0.560 0.230 0.100 0.820
9.42 0.46 0.27 0.41 0.00 0.36 0.74 e
0.002 0.500 0.600 0.520 0.950 0.550 0.390 e
OR e Odds ratio. WMD e Weighted mean difference. CI e Confidence interval. HG e Heterogeneity. P values in bold denote statistical significance at the 5% level. * Outcomes given as WMD.
each surgical technique. For studies that presented continuous data as mean and range values, the standard deviation (SD) was calculated using statistical algorithms and checked using ‘‘bootstrap’’ resampling techniques. Thus all continuous data were standardized for the analysis. Heterogeneity was quantitatively assessed by calculation of Chi square statistic for a given outcome and graphical exploration with funnel plots was used to evaluate publication bias.13,19 Analysis was conducted using Review Manager Version 4.3 (The Cochrane Collaboration, Software Update, Oxford, UK).
Results Studies selected The literature search identified eight studies for potential inclusion in the analysis.2,20e26 five of these were subsequently excluded as there were no extractable comparative
Table 3
results between the open and endovascular approaches.2,22e25 The remaining three20,21,26 studies, comprising 141 patients (37 endovascular and 104 open), were included in the analysis. One study used the Hemobahn graft,20 one Viabahn endografts,21 and the third used the Wall graft in five patients and Viabahn in two patients.26 There were no studies assessing outcome of thrombosed popliteal artery aneurysms that met the inclusion criteria.
Patient characteristics There were 133 (94.3%) men with no significant differences between the open and endovascular groups (Tables 1 and 2). Mean age at intervention and mean aneurysm diameter did not differ significantly between the two groups. Hypertension was noted in 66%, cardiac disease in 46%, pulmonary disease in 17% and diabetes in 20% with no statistically significant differences between the two groups. A smoking history was noted in 66% of patients. In one study,21 bilateral popliteal aneurysms were recorded
Operative details and postoperative complications following endovascular and open popliteal aneurysm repair
Outcome
Operative time (mins) Length of stay (days) 30 Day graft thrombosis 30 Day reintervention Long-term graft patency
No. Studies
1 2 2 1 2
No. Patients Endo
Open
15 30 22 7 30
15 56 63 48 56
OR e Odds ratio. WMD e Weighted mean difference. HR e Hazard ratio. CI e Confidence interval. HG e Heterogeneity. P values in bold denote statistical significance at the 5% level. * Outcomes given as WMD. þ Outcomes given as HR.
OR/WMD*/HRþ (95% CI)
119.9 3.9 5.05 18.80 1.70
(102.1, 137.7)* (4.3, 3.5)* (0.91, 28.11) (1.44, 245.99) (0.33, 8.75)þ
p-value
HG c2
HG p-value
<0.001 <0.001 0.060 0.030 0.530
e 1.29 0.11 e 0.06
e 0.260 0.740 e 0.810
Non-thrombosed Popliteal Aneurysm Repair
Figure 1
99
Forest plot illustrating long-term graft patency following open and endovascular popliteal aneurysm repair
in 42 (63.6%) of 66 patients. One study21 provided details of distal run-off in the open and endovascular groups, with patients having 1, 2 or 3 vessel run-off in approximately 33% of cases in both groups.
Outcomes following open or endovascular popliteal aneurysm repair Duration of the interventional procedure was significantly longer for endovascular interventions than for open repair [WMD 119.9 minutes (95% CI 102.1e137.7), p < 0.001] (Table 3). Postoperative length of stay was significantly shorter following endovascular procedures when compared with open [WMD e 3.9 days (95% CI e 4.3e3.5), p < 0.001]. The incidence of 30 day graft thrombosis and reintervention rates were significantly greater following endovascular repair of popliteal aneurysms. However, medium-term graft patency did not differ significantly between the two groups (Fig. 1).
Discussion This meta-analysis has shown no difference in mediumterm patency comparing open with endovascular treatment of popliteal aneurysms. Patency following ligation and bypass is 70%e94% at five years.27 Similar results are obtained when an open posterior approach is used.28 In a series of 57 PA undergoing endovascular repair from 1998e 2004 a two year primary patency of 77% was achieved.29 Medium-term patency of the 112 PA in our study was 1.70 times greater following open surgery when compared with endovascular approaches. Approximately 30% to 50% of popliteal artery aneurysms are asymptomatic at the time of presentation,3,30 although this can be as high as 80% in some series.31 The avoidance of complications is therefore paramount. Complications following elective open repair of popliteal aneurysms are uncommon. Thirty day mortality is less than 1%, and limb loss less than 2%.27 The commonest postoperative problems involve the surgical wound, occurring in about 5% of cases.32 Both local and systemic complications are greater in patients undergoing open repair of popliteal aneurysms for acute ischaemia.27,32 Early graft failure is uncommon. By contrast, in this study we found that 30 day graft thrombosis was significantly higher in patients undergoing endovascular repair. Similarly, 30 day reintervention was also greater in this group of patients. There were 13 early and late stent-related complications in nine patients from
a group of 67 popliteal artery aneurysms.29 These included migration, with or without endoleaks, stenosis and stent disruption. Endoleak has been described in 20% of endovascular popliteal artery aneurysm repairs at a mean follow up of 16 months.21 It is possible that the included studies may represent pilot studies assessing the feasibility of endovascular repair of popliteal aneurysm. This may go some way to explaining the significantly longer operative time seen in the endovascular group, although this outcome was discussed in only one study. In the absence of further studies from centres with established endovascular practices being available the effect of endovascular repair on operative time needs to be interpreted with some caution. The only advantage which we have demonstrated for endovascular repair is a shorter length of stay in hospital. This needs to be balanced against the greater number of complications seen in these patients. With the technology currently available it is difficult to justify endovascular repair for patent popliteal aneurysms. Future advances in technology and the overcoming of any learning curves may lead to improvements in outcome following endovascular repair of popliteal artery aneurysms and these would need to be reassessed at the appropriate time.
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