over recent decades , there has been a consistent improvement in the short - term mortality associated with elective repair of infrarenal aortic aneurysms ( aaa ) . these improvements have followed general developments in surgical technique and peri - operative procedures , the advent of endovascular surgery , improvements in critical care and vascular anaesthesia , and the centralization of aortic surgery to specialist teams with high operative caseload . the decision to repair an aaa requires consideration of the risk of rupture without surgery , the peri - operative risk of death , and the patient s overall life expectancy ; balanced with the patient s own preference . as the aim of aaa repair is to prolong life through the prevention of rupture , surgery should only be performed if the risk of rupture without surgery outweighs the peri - operative risk of surgery itself , in patients whose life expectancy is long enough to result in long - term benefit . it is therefore perhaps unsurprising that short - term operative mortality has been the primary focus of most outcomes research reporting the results of aaa repair . however , longer - term mortality continues to be concerning in the years that follow surgery , as patients with aaa have considerable cardiovascular risk factors compared with the wider population . it remains unknown whether improvements in the peri - operative safety of aaa repair have translated to improved 5 year survival following surgery . long - term survival critically influences the cost - effectiveness of aaa repair , and is a key measure to justify surgical intervention at a population level . understanding trends in published results will clarify whether long - term survival is an appropriate therapeutic target for further research . the aim of this study was to quantitatively summarise the evidence for 5 year survival after elective infrarenal aaa repair to assess whether improvements in peri - operative practice have translated into better long - term mortality over time . an electronic search of all english - language literature was performed using the embase and medline databases , covering the years 19502013 , in accordance with preferred items for reporting of systematic reviews and meta analyses ( prisma ) guidelines ( fig . 1 ) . the free - text search terms  abdom * ,   aortic aneurysm , surger * ,   surgical * ,   repair * ,   surviv * ,   mortal * ,   electiv * ,   elect * ,   emergenc * ,  and mesh/ emtree terms aortic aneurysm , abdominal , surgical procedures , operative , mortality , survival rate , disease - free survival , surgical procedures , elective ,  [ mesh ] and  abdominal aorta aneurysm , surgery , aorta surgery , abdominal surgery , aneurysm surgery , survival , disease free survival , failure free survival , long term survival , post treatment survival , survival rate , survival time , mortality , surgical mortality , elective surgery ,  [ emtree ] were used in combination with the boolean operators and or or and not ( appendix i ) . refworks software ( refworks , bethesda , md , usa ) was used to de - duplicate the electronic search results . grey literature and reference lists from relevant papers were reviewed to identify other studies that may have contained relevant data . the inclusion criteria for this meta - analysis comprised studies reporting 4 year , 5 year , or 6 year survival after elective repair of an infrarenal aortic aneurysm , using a principled statistical technique to account for loss to follow up , other censoring of data , or varying recruitment over time . studies were excluded if they did not report the  numbers at risk  at 5 years or at both 4 and 6 years . abstracts of citations identified from the literature search were reviewed by two of the authors ( ssb and bop ) , who then independently extracted all relevant data . any disagreements were resolved by consensus agreement ; this was overseen and arbitrated when necessary by another of the authors ( ak ) . studies were also excluded where data for patients with aaa were not separable from data for patients with other aneurysm morphologies ( juxtarenal , suprarenal , thoracoabdominal ) or occlusive aortic disease , if no date range for the study was given , if emergent and elective survival was not reported separately , and if specific age or comorbidity patient subgroups were reported without survival data for the patient group as a whole . data were extracted regarding each study s country of origin , study timeframe and midpoint , medical therapies such as antiplatelet and statin therapy and comorbidity data such as known ischaemic heart disease , diabetes mellitus , or smoking status . the mean / median aneurysm diameter for patients undergoing surgery was extracted where described . a random effects meta - analysis meta - regression was performed to assess whether 5 year survival was associated with study midpoint or aneurysm diameter at the time of surgery . the meta - analysis to quantify 5 year survival was performed using a random effects model ( dictated by the large degree of heterogeneity among the studies included in the analysis ) as per dersimonian and laird on the log odds of survival outcome scale . all meta - analyses and meta - regressions treated the arm level data as independent and so any correlation resulting from arms from the same study was ignored in analysis . were calculated using a conservative sample size ( number at risk at 5 years / survival probability ) to produce large within study variances such that censoring had the most effect in increasing the uncertainty of the study arm estimates . for studies that only provided 4 year and 6 year survival values , and number of patients at risk , averaging the 4 year and 6 year values derived the 5 year survival value . a random effects meta - regression analysis was carried out to assess the change , if any , over the timescale that these studies covered using moments estimator methodology . this analysis used the same outcome data as in the meta - analysis for survival ; and study mid - date ( in years ) was used as the only covariate . this analysis resulted in a log - odds ratio of survival associated with a 1 year change in study mid - date , where a positive log - odds ratio indicated that the probability of 5 year survival after aaa repair increased over time . a second random effects meta - regression analysis was conducted to evaluate the effect of aneurysm diameter on 5 year survival , while adjusting for the effect of time . this analysis used study mid - date and the mean diameter ( in mm ) as covariates , so that an adjusted ( for time ) log - odds ratio associated with a 1 mm increase in mean diameter was obtained . here a positive log - odds ratio indicated that the survival probability increased as mean diameter increased . finally , a third random effects meta - regression was conducted using mid - date and average patient age ( in years ) , so that an adjusted ( for time ) log - odds ratio associated with a 1 year increase in age was obtained . here a positive log - odds ratio indicated that the survival probability increased as age increased . the meta - analysis to quantify 5 year survival was performed using a random effects model ( dictated by the large degree of heterogeneity among the studies included in the analysis ) as per dersimonian and laird on the log odds of survival outcome scale . all meta - analyses and meta - regressions treated the arm level data as independent and so any correlation resulting from arms from the same study was ignored in analysis . within - study variances were calculated using a conservative sample size ( number at risk at 5 years / survival probability ) to produce large within study variances such that censoring had the most effect in increasing the uncertainty of the study arm estimates . for studies that only provided 4 year and 6 year survival values , and number of patients at risk , averaging the 4 year and 6 year values derived the 5 year survival value . a random effects meta - regression analysis was carried out to assess the change , if any , over the timescale that these studies covered using moments estimator methodology . this analysis used the same outcome data as in the meta - analysis for survival ; and study mid - date ( in years ) was used as the only covariate . this analysis resulted in a log - odds ratio of survival associated with a 1 year change in study mid - date , where a positive log - odds ratio indicated that the probability of 5 year survival after aaa repair increased over time . a second random effects meta - regression analysis was conducted to evaluate the effect of aneurysm diameter on 5 year survival , while adjusting for the effect of time . this analysis used study mid - date and the mean diameter ( in mm ) as covariates , so that an adjusted ( for time ) log - odds ratio associated with a 1 mm increase in mean diameter was obtained . here a positive log - odds ratio indicated that the survival probability increased as mean diameter increased . finally , a third random effects meta - regression was conducted using mid - date and average patient age ( in years ) , so that an adjusted ( for time ) log - odds ratio associated with a 1 year increase in age was obtained . here a positive log - odds ratio indicated that the survival probability increased as age increased . thirty - six studies reported 107,814 patients from 14 different countries between 1969 and 2011 and contributed to survival meta - analysis and a meta - regression of the relationship between 5 year survival and study mid - point ( prisma diagram and table 1 ) . of these , 18 studies consisting of 13,281 patients contributed to the meta - regression of the relationship between aneurysm diameter at the time of surgery and subsequent 5 year survival ( table 2 ) . information to describe comorbid conditions and medication was limited ; eight studies reported the proportion of patients prescribed statin or antiplatelet agents but with limited data on dose regimens . twenty - nine of 36 studies reported relevant comorbidity but with poor precision in classification ( table 3 ) . there was a wide range of prevalence of diabetes ( 5.422.7% ) , dyslipidaemia ( 11.056.2% ) , ischaemic heart disease ( 25.082.7% ) , and hypertension ( 24.083.7% ) between studies , reflecting considerable variation in reporting standards . fifteen of these 29 studies reported the percentage of active smokers ( 16.082.9% ) , with six of the 29 studies reporting the percentage of ex - smokers ( 48.077.2% ) . of the eight studies reporting concomitant medication , the range of patients on antiplatelet agents was 40.572.6% and 14.869.1% were reported as taking a statin . mean age and study characteristics for all studies included in these analyses are also reported ( tables 4 and 5 ) . thirty - six studies consisting of 60 study arms and a total of 107,814 patients , covering the period 1969 to 2011 ( table 1 ) contributed to the meta - analysis of 5 year survival after aaa repair . of the patients , 80.3% ( 86,475/107,691 ) were male and 49.9% ( 53,490/107,251 ) underwent open repair . the pooled estimate for 5 year survival after elective aaa repair was 69% ( 95% ci 67 to 71% , i = 87% ; fig . meta - regression conducted to evaluate the survival trend over time demonstrated that there was no significant improvement ( or deterioration ) in 5 year survival over the period that these data span ( log or 0.001 , 95% ci 0.014 to 0.012 , i = 87% ; fig . 3 ) . eighteen studies , consisting of 29 study arms , provided mean aneurysm diameter data and were included in this analysis . this comprised 13,281 patients with a mean aneurysm diameter range of 46.3 mm to 68 mm , from data covering the period 19782011 ( table 2 ) . meta - regression demonstrated that larger aneurysm diameter at the time of surgery was associated with poorer 5 year survival ( adjusted log or 0.058 , 95% ci 0.095 to 0.021 , i = 85% ) . there was no evidence of significant improvement ( or deterioration ) in 5 year survival ( adjusted log or 0.015 , 95% ci 0.020 to 0.050 ) . visualizing regression analyses for more than a single covariate is difficult , and here 4 a plot is shown for a meta - regression where the only covariate is the mean diameter . the resulting unadjusted log or ( 0.052 , 95% ci 0.088 to 0.017 , i = 86% ) is very similar to the adjusted one . twenty - four studies , consisting of 40 study arms , provided mean age data and were included in this analysis . this comprised 103,021 patients with a mean age range of 63 years to 78.5 years , from data covering the period 19782011 ( table 5 ) . meta - regression demonstrated that older patient age at the time of surgery was associated with poorer 5 year survival ( adjusted log or 0.118 , 95% ci 0.142 to 0.094 , i = 70% ) . having adjusted for mean patient age in this meta - regression , there was evidence of significant improvement in 5 year survival over the period that these data span ( adjusted log or 0.027 , 95% ci 0.012 to 0.042 ) . as both estimated effects in this meta - regression are quite large and statistically significant it is difficult to visualize this regression model using two dimensions . this meta - regression model predicts 5 year survival probabilities in 1970 of around 72% , 58% , and 44% in patients aged 65 , 70 , and 7,5 respectively ; in 2010 the meta - regression model predicts 5 year survival probabilities of around 88% , 81% , and 70% at these three patient ages , respectively . thirty - six studies consisting of 60 study arms and a total of 107,814 patients , covering the period 1969 to 2011 ( table 1 ) contributed to the meta - analysis of 5 year survival after aaa repair . of the patients , 80.3% ( 86,475/107,691 ) were male and 49.9% ( 53,490/107,251 ) underwent open repair . the pooled estimate for 5 year survival after elective aaa repair was 69% ( 95% ci 67 to 71% , i = 87% ; fig . meta - regression conducted to evaluate the survival trend over time demonstrated that there was no significant improvement ( or deterioration ) in 5 year survival over the period that these data span ( log or 0.001 , 95% ci 0.014 to 0.012 , i = 87% ; fig . eighteen studies , consisting of 29 study arms , provided mean aneurysm diameter data and were included in this analysis . this comprised 13,281 patients with a mean aneurysm diameter range of 46.3 mm to 68 mm , from data covering the period 19782011 ( table 2 ) . meta - regression demonstrated that larger aneurysm diameter at the time of surgery was associated with poorer 5 year survival ( adjusted log or 0.058 , 95% ci 0.095 to 0.021 , i = 85% ) . there was no evidence of significant improvement ( or deterioration ) in 5 year survival ( adjusted log or 0.015 , 95% ci 0.020 to 0.050 ) . visualizing regression analyses for more than a single covariate is difficult , and here 4 a plot is shown for a meta - regression where the only covariate is the mean diameter . the resulting unadjusted log or ( 0.052 , 95% ci 0.088 to 0.017 , i = 86% ) is very similar to the adjusted one . twenty - four studies , consisting of 40 study arms , provided mean age data and were included in this analysis . this comprised 103,021 patients with a mean age range of 63 years to 78.5 years , from data covering the period 19782011 ( table 5 ) . meta - regression demonstrated that older patient age at the time of surgery was associated with poorer 5 year survival ( adjusted log or 0.118 , 95% ci 0.142 to 0.094 , i = 70% ) . having adjusted for mean patient age in this meta - regression , there was evidence of significant improvement in 5 year survival over the period that these data span ( adjusted log or 0.027 , 95% ci 0.012 to 0.042 ) . as both estimated effects in this meta - regression are quite large and statistically significant it is difficult to visualize this regression model using two dimensions . this meta - regression model predicts 5 year survival probabilities in 1970 of around 72% , 58% , and 44% in patients aged 65 , 70 , and 7,5 respectively ; in 2010 the meta - regression model predicts 5 year survival probabilities of around 88% , 81% , and 70% at these three patient ages , respectively . early survival after elective aaa repair has improved dramatically over the last 50 years ; the advent and rapid uptake of evar has played a part , as have improved preoperative optimisation strategies , and peri- and post - operative critical care management . this study , however , demonstrates that there has been no measurable improvement in the overall long - term survival of patients undergoing elective infrarenal aaa repair , because increasingly elderly cohorts have been treated over the time period examined . after adjustment for the increasing age of patients undergoing aaa repair , long - term survival improved over time . the pooled survival estimate reported is identical to registry data reported from the swedvasc prospectively maintained registry covering the periods 19872005 . although there was an improvement in age adjusted survival , long - term mortality remains concerning for this cohort despite improvements in cardiovascular risk prevention strategies , peri - operative and post - operative management of aortic surgery , and vastly improved peri - operative mortality rates , especially since the advent and implementation of evar . a western australia study that retrospectively reviewed long - term survival in survivors of elective aaa surgery reported that 57.9% of deaths after 30 days in this patient group were attributable to cardiovascular causes . existing evidence demonstrates that patients with aaa have at least a twofold increase in 5 year mortality compared with matched controls , and that this increases with aorta diameter despite surgical repair . studies have also reported that patients with aneurysmal aortas have an unusually pronounced burden of widespread cardiovascular disease , and that patients with aaa suffer from significant multisystem atherosclerosis , causing higher rates of heart attacks , strokes , and major amputation . where comorbidity was reported , the patients included in this study had a characteristically high burden of multisystem atherosclerosis . however , the relative paucity of data to describe comorbidity also demonstrates the lack of clear reporting standards and definitions in the existing literature documenting long - term outcome for aaa repair . ischaemic heart disease was reported variously from  previous myocardial infarction  to  previous coronary artery intervention  to  known ischaemic heart disease .  similarly the definition of abnormal lipids ranged from dyslipidaemia to hypercholesterolemia . reporting of concomitant preventative medication such as antiplatelet agents and statins was also very limited ( table 3 ) , with little information on dosage regimens or the particular details of individual drugs that were used . the link between larger aneurysm diameter and poorer outcome has been described extensively in the past . the uk small aneurysm trial reported that baseline aaa diameter was associated with increasing risks of non - aneurysm related mortality and of cardiovascular mortality before / after surgery ; even after adjustment for other known risk factors . the interaction between aaa diameter and factors such as gender , age , smoking , hypertension , hypercholesterolemia , and underlying genetic predisposition is likely to play an important role for this association , but remains incompletely understood . studies to modify cardiovascular risk in patients with similar cardiovascular profile to those with aaa have demonstrated that multifactorial goal directed strategies can significantly reduce mid - term mortality . the same is true for smoking cessation interventions , proactive prescribing of risk modifying drugs , supervised exercise programmes , and the management of other contributory risk factors such as hypertension . focused research is required to assess whether such efforts could modify long - term survival in patients undergoing elective aaa repair and , perhaps more importantly , whether patient selection needs addressing to ensure only those likely to enjoy a survival benefit are offered intervention . this study was limited by the changes in clinical practice over a long included timescale . given the range of studies analysed , time period covered , and varied numbers of contributing patients from each study , the pooled analysis was associated with considerable statistical and methodological heterogeneity . meta - regression techniques are susceptible to aggregation bias or ecological fallacy . in the absence of individual patient data , associations identified from between - study relationships this study does not take into account potential variability of life expectancy in the different countries that have contributed to the overall analyses . it is clear that focused research is needed to further improve the long - term survival of patients undergoing elective aaa repair . goal directed medical therapy and behavioural interventions have a well established role in patients surviving coronary intervention ; and require focused appraisal in patients with aaa . research should also address the objectivity of patient selection , as it may be possible to identify a cohort with aaa whose long - term survival is not modifiable regardless of aaa repair . this study was limited by the changes in clinical practice over a long included timescale . given the range of studies analysed , time period covered , and varied numbers of contributing patients from each study , the pooled analysis was associated with considerable statistical and methodological heterogeneity . meta - regression techniques are susceptible to aggregation bias or ecological fallacy . in the absence of individual patient data , associations identified from between - study relationships this study does not take into account potential variability of life expectancy in the different countries that have contributed to the overall analyses . it is clear that focused research is needed to further improve the long - term survival of patients undergoing elective aaa repair . goal directed medical therapy and behavioural interventions have a well established role in patients surviving coronary intervention ; and require focused appraisal in patients with aaa . research should also address the objectivity of patient selection , as it may be possible to identify a cohort with aaa whose long - term survival is not modifiable regardless of aaa repair . survivors of elective aaa repair continue to have poor life expectancy despite surgery , although age adjusted survival has improved . medline ; aortic aneurysm , abdominal/ ; 12672 results . medline ; ( abdom * adj5  aortic aneurysm*).ti , ab ; 11980 results . medline ; ( surger * or surgical * or repair*).ti , ab ; 1326166 results . medline ; ( surviv * or mortal*).ti , ab ; 1005533 results . medline ; 10 or 11 or 12 or 13 ; 1127177 results . medline ; ( elect * or choice * or choos*).ti , ab ; 1571983 results . medline ; ( ( non or  not  ) adj5 emergenc*).ti , ab ; 5992 results . abdominal aorta aneurysm/ ( abdom * adj5  aortic aneurysm*).ti , ab . (  abdom * aort *  adj5 aneurysm*).ti , ab . surgery / or exp aorta surgery / or exp abdominal surgery / or exp aneurysm surgery/ ( surviv * or mortal*).ti , ab . survival / or disease free survival / or exp failure free survival / or long term survival / or post treatment survival / or survival rate / or survival time/ mortality / or surgical mortality/ ( elect * or choice * or choos*).ti , ab . ( ( non or  not  ) adj5 emergenc*).ti , ab . limit 18 to english language
backgroundimproved critical care , pre - operative optimization , and the advent of endovascular surgery ( evar ) have improved 30 day mortality for elective abdominal aortic aneurysm ( aaa ) repair . 
 it remains unknown whether this has translated into improvements in long - term survival , particularly because these factors have also encouraged the treatment of older patients with greater comorbidity . 
 the aim of this study was to quantify how 5 year survival after elective aaa repair has changed over time.methodsa systematic review was performed identifying studies reporting 5 year survival after elective infrarenal aaa repair . 
 an electronic search of the embase and medline databases was conducted to january 2014 . 
 thirty - six studies , 60 study arms , and 107,814 patients were identified . 
 meta - analyses were conducted to determine 5 year survival and to report whether 5 year survival changed over time.resultsfive-year survival was 69% ( 95% ci 67 to 71% , i2 = 87% ) . 
 meta - regression on study midpoint showed no improvement in 5 year survival over the period 19692011 ( log or 0.001 , 95% ci 0.0140.012 ) . 
 larger average aneurysm diameter was associated with poorer 5 year survival ( adjusted log or 0.058 , 95% ci 0.095 to 0.021 , i2 = 85% ) . 
 older average patient age at surgery was associated with poorer 5 year survival ( adjusted log or 0.118 , 95% ci 0.142 to 0.094 , i2 = 70% ) . after adjusting for average patient age , 
 an improvement in 5 year survival over the period that these data spanned was obtained ( adjusted log or 0.027 , 95% ci 0.012 to 0.042).conclusionfive - year survival remains poor after elective aaa repair despite advances in short - term outcomes and is associated with aaa diameter and patient age at the time of surgery . 
 age - adjusted survival appears to have improved ; however , this cohort as a whole continues to have poor long - term survival . 
 research in this field should attempt to improve the life expectancy of patients with repaired aaa and to optimise patient selection .