***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Objective : To assess the outcome of endovascular repair ( EVAR ) of small abdominal aortic aneurysms ( AAA , ≤5.5 mm maximum diameter ) in Australia . Summary Background Data : R and omized trials have suggested that small AAAs should not be treated by open surgery . EVAR is associated with less perioperative mortality than open surgery for large AAAs . We assessed the outcome of EVAR of small AAAs as part of a national audit . Methods : ASERNIP-S carried out a prospect i ve audit of EVAR performed between November 1999 and May 2001 in Australia . A total of 478 of the 961 patients entered underwent treatment of a small AAA . Data were collected regarding preoperative characteristics , procedural outcome , and intermediate success . Median follow-up was 3.2 years . Data were analyzed using Kaplan-Meier and Cox proportional hazard analyses . Results : The 30-day mortality and technical success rates were 1.1 % and 98 % , respectively . Postoperative complications occurred in 29 % . Survival was 84 % and 52 % at 3 and 5 years , respectively . Primary , assisted primary , and secondary clinical success rates were 72 % , 79 % , and 82 % , respectively , at 3 years . Reintervention rate was 11 % at 3 years ; however , 15 % of patients continued to have significant aortic sac enlargement . Survival was reduced in patients considered unfit for general anesthesia ( odds ratio = 2.6 ; 95 % confidence interval , 1.4–4.8 , P = 0.002 ) or those who had elevated preoperative serum creatinine ( odds ratio = 2.0 ; 95 % confidence interval , 1.3–3.0 , P = 0.001 ) . Conclusions : EVAR can be carried with good perioperative outcome in patients with small AAA ; however , intermediate success is hampered by the need for reintervention and continued aortic sac enlargement . At present , widespread treatment of small AAAs by EVAR would appear inappropriate OBJECTIVE The effect of population screening for abdominal aortic aneurysm ( AAA ) disease on morbidity and mortality has been comprehensively studied and reported . However , the effect of early AAA detection on suitability for  endovascular aneurysm repair ( EVAR )  remains unknown . Considering the importance of such an effect on future health economics , we sought to assess the possible effect of AAA ultrasound surveillance on suitability for EVAR . METHODS This was a prospect i ve cohort study . From January 2002 to August 2003 , consecutive AAA patients selected for open elective repair were placed into one of two groups according to mode of presentation . The first group included patients referred from a local well-established AAA ultrasound screening and surveillance program ( ultrasound surveillance [ AAA-S ] group ) . The second group included patients referred from neighboring unscreened regions with incidentally diagnosed AAA ( incidental [ AAA-I ] group ) . All patients underwent  preoperative computed tomographic angiography . By using three-dimensional reconstruction software , computed tomographic images were assessed by two blinded observers for suitability for EVAR by using the criteria for a modular endovascular device . RESULTS Of 74 patients included in the study , 41 were in the AAA-S group , and 31 were in the AAA-I group . The median aneurysm diameter was 72.3 mm ( range , 50.7 - 83.7 mm ) for AAA-I and 65 mm ( range , 50.7 - 79.2 mm ) for AAA-S ( P < .47 ) . Suitability for EVAR was 41 % in the AAA-S group and 45 % in the AAA-I group ( P < .47 ) . CONCLUSIONS Early detection and surveillance of AAA does not seem to increase suitability for EVAR . Suitability for EVAR seems to be determined early on in an aneurysm 's life . On the basis of current device technology , referral for intervention from an AAA surveillance program may need to be initiated at a size well below 5.5 cm if an increase in EVAR suitability is to be expected HYPOTHESIS Small infrarenal abdominal aortic aneurysms have a more favorable clinical and morphologic outcome compared with medium and large abdominal aortic aneurysms following  endovascular aneurysm repair(EVAR  ) . DESIGN A prospect i ve clinical series of 206 patients undergoing elective EVAR between 1996 and 2001 . SETTING A tertiary care academic health center . PATIENTS Patients were grouped according to aneurysm size : small ( < 50 mm ) , medium ( 50 - 60 mm ) , and large ( > 60 mm ) . INTERVENTIONS Primary EVAR and secondary procedures to secure fixation of the stent graft and surgical conversions . MAIN OUTCOME MEASURES Aneurysm diameter , endoleaks , and long-term morphologic changes were analyzed postoperatively with 3-dimensional reconstructions of computed tomographic angiograms . RESULTS Groups were similar in age , comorbidities , and follow-up ( mean + /- SD , 32.1 + /- 11.8 months ) . There were 30 small aneurysms , 92 medium aneurysms , and 84 large aneurysms , with a mean size of 45.1 + /- 3.7 mm , 53.8 + /- 3.1 mm , and 66.1 + /- 6.8 mm , respectively ( P<.01 ) . There was no significant difference in proximal neck or iliac artery diameter among the 3 groups . The proximal aortic neck length ( 28.1 + /- 11.6 mm [ small ] ; 23.9 + /- 11.3 mm [ medium ] ; and 22.1 + /- 11.6 mm [ large ] ; P<.05 ) was significantly shorter in large aneurysms . Furthermore , there was a significant increase ( 6 % [ small ] ; 15 % [ medium ] ; and 21 % [ large ] ; P<.05 ) in angulated necks in large aneurysms . Following treatment , aneurysm diameter remained stable in most patients ( 83 % [ small ] ; 82 % [ medium ] ; and 83 % [ large ] ) , with a mean decrease of 2.0 + /- 6.5 mm , 2.1 + /- 6.1 mm , and 3.7 + /- 7.7 mm in each group , respectively ( P = .45 ) . There was no difference in the incidence of endoleaks , aneurysm contraction , or aneurysm expansion based on preoperative aneurysm diameter . Secondary procedures were performed in 5 ( 20 % ) of 25 , 9 ( 5.2 % ) of 170 , and 5 ( 36 % ) of 11 aneurysms that contracted , remained stable , or exp and ed , respectively , following EVAR ( P<.05 ) . CONCLUSIONS There is a 15 % increase in neck angulation and a 27 % decrease in neck length in large compared with small infrarenal abdominal aortic aneurysms , with no difference in outcome . Aneurysms that are stable following EVAR have a significantly lower incidence of requiring secondary procedures OBJECTIVE To compare the outcome of patients with small abdominal aortic aneurysms ( AAA ) treated in a prospect i ve trial of endovascular aneurysm repair ( EVAR ) to patients r and omized to the surveillance arm of the UK Small Aneurysm Trial . METHOD All patients with small AAA ( < or = 5.5 cm diameter ) treated with a stent graft ( EVARsmall ) in the multicenter AneuRx clinical trial from 1997 to 1999 were review ed with follow up through 2003 . A subgroup of patients ( EVARmatch ) who met the age ( 60 - 76 years ) and aneurysm size ( 4.0 - 5.5 cm diameter ) inclusion criteria of the UK Small Aneurysm Trial were compared to the published results of the surveillance patient cohort ( UKsurveil ) of the UK Small Aneurysm Trial ( NEJM 346:1445 , 2002 ) . Endpoints of comparison were aneurysm rupture , fatal aneurysm rupture , operative mortality , aneurysm related death and overall mortality . The total patient years of follow-up for EVAR patients was 1369 years and for UK patients was 3048 years . Statistical comparisons of EVARmatch and UKsurveil patients were made for rates per 100 patient years of follow up ( /100 years ) to adjust for differences in follow-up time . RESULTS The EVARsmall group of 478 patients comprised 40 % of the total number of patients treated during the course of the AneuRx clinical trial . The EVARmatch group of 312 patients excluded 151 patients for age < 60 or > 76 years and 15 patients for AAA diameter < 4 cm . With the exception of age , there were no significant differences between EVARsmall and EVARmatch in pre-operative factors or post-operative outcomes . In comparison to the UKsurveil group of 527 patients , the EVARmatch group was slightly older ( 70 + /- 4 vs. 69 + /- 4 years , p = 0.009 ) , had larger aneurysms ( 5.0 + /- 0.3 vs. 4.6 + /- 0.4 cm , p < 0.001 ) , fewer women ( 7 vs. 18 % , p < 0.001 ) , and had a higher prevalence of diabetes and hypertension and a lower prevalence of smoking at baseline . Ruptures occurred in 1.6 % of EVARmatch patients and 5.1 % of UKsurveil patients ; this difference was not significant when adjusted for the difference in length of follow up . Fatal aneurysm rupture rate , adjusted for follow up time , was four times higher in UKsurveil ( 0.8/100 patient years ) than in EVARmatch ( 0.2/100 patient years , p < 0.001 ) ; this difference remained significant when adjusted for difference in gender mix . Elective operative mortality rate was significantly lower in EVARmatch ( 1.9 % ) than in UKsurveil ( 5.9 % , p < 0.01 ) . Aneurysm-related death rate was two times higher in UKsurveil ( 1.6/100 patient years ) than in EVARmatch ( 0.8/100 patient years , p = 0.03 ) . All-cause mortality rate was significantly higher in UKsurveil ( 8.3/100 patient years ) than in EVARmatch ( 6.4/100 patient years , p = 0.02 ) . CONCLUSIONS It appears that endovascular repair of small abdominal aortic aneurysms ( 4.0 - 5.5 cm ) significantly reduces the risk of fatal aneurysm rupture and aneurysm-related death and improves overall patient survival compared to an ultrasound surveillance strategy with selective open surgical repair OBJECTIVE To study the growth rate and factors influencing progression of small infrarenal abdominal aortic aneurysms ( AAA ) .  DESIGN Observational , longitudinal , prospect i ve study . PATIENTS AND METHODS We followed patients with AAA < 5 cm in diameter in two groups . Group I ( AAA 3 - 3.9 cm , n = 246 ) underwent annual ultrasound scans . Group II ( AAA 4 - 4.9 cm , n = 106 ) underwent 6-monthly CT scans . RESULTS We included 352 patients ( 333 men and 19 women ) followed for a mean of 55.2+/-37.4 months ( 6.3 - 199.8 ) . The mean growth rate was significantly greater in group II ( 4.72+/-5.93 vs. 2.07+/-3.23 mm/year ; p<0.0001 ) . Group II had a greater percentage of patients with rapid aneurysm expansion ( > 4 mm/year ) ( 36.8 vs. 13.8 % ; p<0.0001 ) . The classical cardiovascular risk factors did not influence the AAA growth rate in group I. Chronic limb ischemia was associated with slower expansion ( < or = 4 mm/year ) ( OR 0.47 ; CI 95 % 0.22 - 0.99 ; p = 0.045 ) . Diabetic patients in group II had a significantly smaller mean AAA growth rate than non-diabetics ( 1.69+/-3.51 vs. 5.22+/-6.11 mm/year ; p = 0.032 ) . CONCLUSIONS The expansion rate of small AAA increases with the AAA size . AAA with a diameter of 3 - 3.9 cm exp and slowly , and they are very unlikely to require surgical repair in 5 years . Many 4 - 4.9 cm AAA can be expected to reach a surgical size in the first 2 years of follow-up . Chronic limb ischemia and diabetes are associated with reduced aneurysm growth rates BACKGROUND Although the initial results of endovascular repair of abdominal aortic aneurysms were promising , current evidence from controlled studies does not convincingly show a reduction in 30-day mortality relative to that achieved with open repair . METHODS We conducted a multicenter , r and omized trial comparing open repair with endovascular repair in 345 patients who had received a diagnosis of abdominal aortic aneurysm of at least 5 cm in diameter and who were considered suitable c 
    Output:
    
Pooled estimates were not influenced by follow-up length .
Conversion and reintervention rates were not significantly lower for small AAA .
EVAR in small versus large AAA might be associated with lower operative mortality , aneurysm-related mortality and aneurysm rupture .