***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    Input: The long‐term effects of abdominal aortic aneurysm ( AAA ) screening were investigated in extended follow‐up from the UK Multicentre Aneurysm Screening Study ( MASS ) r and omized trial Context Is it cost-effective to screen older adults for abdominal aortic aneurysm ( AAA ) ? Contribution This 7-year follow-up report of a large r and omized trial in the United Kingdom found that men age 65 to 74 years who were invited to have ultrasonography and surveillance for AAA  had lower mortality rates than did those who were not invited ( hazard ratio , 0.53 [ CI , 0.42 to 0.68 ] ) . Cost-effectiveness for AAA-related deaths , based on costs applied to the events experienced by the men , was estimated at $ 19500 ( CI , $ 12400 to $ 39800 ) per life-year gained . Caution s Only men were studied .  Actual costs of screening and surveillance  may vary substantially in different setting s. The Editors A fast-growing body of literature is providing evidence in favor of screening men for abdominal aortic aneurysm ( AAA ) . Several large , r and omized trials published in the past few years ( 14 ) have consistently shown that screening reduces AAA-related mortality . A few observational studies of programs under way in localized areas have established the feasibility of systematic screening and have explored its practical implementation ( 57 ) . In addition to the mortality benefit , evidence indicating that screening is highly cost-effective is increasing ( 811 ) . In light of this evidence , national screening programs are now being considered in many countries ( 1214 ) . However , there is little evidence regarding long-term outcomes after AAA screening ; almost all of the evidence from r and omized trials is limited to the first 4 years after screening ( 14 ) . Moreover , long-term cost-effectiveness has been estimated only through health economic modeling ( 10 ) . We describe cost-effectiveness based on 7-year follow-up from the largest of the 4 trials of AAA screeningthe Multicentre Aneurysm Screening Study ( MASS ) ( 2 ) . The trial r and omly assigned approximately 67800 men age 65 to 74 years to receive an invitation to screening or to not receive an invitation .  At 4-year follow-up , the trial reported a substantial relative reduction of 42 % ( 95 % CI , 22 % to 58 % ) in AAA-related mortality and an incremental cost-effectiveness ratio of $ 44900 ( CI , $ 24000 to $ 231000 ) per life-year gained ( 9 ) , which is at the borderline of the commonly accepted threshold for interventions . All values are reported in U.S. dollars ( U.K. 1 = U.S. $ 1.58 ) ( 15 ) . The costs of AAA screening are primarily incurred at the start of the program , but benefits continue to accrue in terms of life-years gained in patients in whom AAA rupture is avoided through elective surgery . It is therefore expected that cost-effectiveness of screening will improve over time . The mid-term results of MASS provide reliable , trial-based information regarding clinical outcomes and cost-effectiveness over a longer period . Methods The details of the MASS protocol were described previously ( 2 ) , but a brief summary is provided ( Figure 1 ) . Between 1997 and 1999 , a population -based sample of 70495 men age 65 to 74 years from 4 centers in the United Kingdom was identified by obtaining records for every man in this age range who was registered with a family physician ( registered persons account for approximately 98 % of the population ) . Persons who were ineligible for the trial ( incorrect details , known AAA , previous AAA surgery , or terminal illness ) were excluded before r and omization . The remaining 67770 men were r and omly assigned to receive an invitation to ultrasonography for AAA or to not receive an invitation to ultrasonography . At screening , men with an aortic diameter of 3.0 cm or greater were defined as having an AAA and were subsequently invited for recall scans to monitor growth of the aneurysm . Men with an aortic diameter of 3.0 to 4.4 cm were rescreened every year , and those with an aortic diameter of 4.5 to 5.4 cm were rescreened every 3 months . Participants were considered for elective surgery when the aortic diameter reached 5.5 cm , aortic expansion was 1.0 cm or more in 1 year , or they experienced symptoms attributable to the aneurysm . Men with an aortic diameter less than 3.0 cm on the initial scan were not rescreened . Blood pressure was also measured ; although family physicians were informed of these measurements , no further intervention was provided through the screening program . We obtained approval from local ethics committees at each center , and all patients who had screening provided signed informed consent . Figure 1 . Study flow diagram . Additional data on follow-up scans and AAA surgeries were collected from hospital records . Deaths up to 31 March 2005 were confirmed by the U.K. Office of National Statistics after matching of the unique National Health Service number for each person . Follow-up ranged from 5.9 to 8.2 years ( mean , 7.1 years ) . The primary outcome of interest , AAA-related mortality , is defined as all deaths within 30 days of any AAA surgery ( elective or emergency ) plus all deaths with International Classification of Diseases , Ninth Revision , codes 441.3 ( ruptured abdominal aortic aneurysm ) , 441.4 ( abdominal aortic aneurysm without mention of rupture ) , 441.5 ( ruptured aortic aneurysm at unspecified site ) , or 441.6 ( aortic aneurysm at unspecified site without mention of rupture ) . The use of codes 441.5 and 441.6 may result in inclusion of some thoracic aortic aneurysm deaths . Investigation of the accuracy of cause-of-death coding on the death certificates was done by an independent mortality working party that was blinded to group allocation . The results of this analysis showed that inaccuracies in coding did not have an important impact on study outcomes ( 2 ) . Statistical Analysis All analyses were done by using Stata , version 9 ( Stata Corp. , College Station , Texas ) . Deaths related to AAA ( primary analysis ) and all-cause mortality ( secondary analysis ) were compared between the 2 r and omized groups by using unadjusted Cox regression by intention-to-treat analysis . Adjustment for age at baseline did not influence the results . The proportional hazards assumption was tested by using Schoenfeld residuals . An unbiased r and omization-based estimate of the benefit of  screening  was also obtained ( 16 ) . This estimate is calculated by subtracting from the control group a subgroup that is equivalent in terms of survival to the nonadherent subgroup in the invited group . Thus , the remaining controls are comparable to the group of invited patients who attended screening . Life-years gained are estimated as the area between the KaplanMeier curves for both groups ( 17 ) . The cost-effectiveness of screening  is estimated from a health service perspective for follow-up truncated at 7 years , with adjustment for censoring ( 18 ) . Details of the costing exercise in the trial at 20002001 prices were reported previously ( 9 ) . The unit costs obtained ( U.K. 1 = U.S. $ 1.58 for the year 2000 [ 15 ] ) are inflated to the 20042005 financial-year level by using annual hospital and community health services pay and price inflation indices ( 19 ) . Costs are applied to the following events on the basis of individual re source use : invitation to screening ( $ 2.46 ) , reinvitation after nonresponse ( $ 2.42 ) , initial scan ( $ 35.95 ) , recall scan ( $ 86.74 ; done in the hospital rather than in the community and including costs for periodic routine meetings with a consultant ) , consultation for elective surgery ( $ 583.79 ) , elective AAA surgery ( $ 13015.74 ) , and emergency AAA surgery ( $ 21054.32 ) . Costs relating to scans of incidentally detected AAAs in the control group are not included ( data not available ) , but costs relating from result ant AAA repair surgery are included . Sensitivity analyses were done by using 1 ) costs retained at the 20002001 financial-year level for comparison with previous publications , 2 ) quality -adjusted life-years based on age-related reductions , 3 ) U.S.-based unit cost estimates for scans and surgeries , 4 ) an increase of 50 % in the cost of a consultation  ( a U.S.-based estimate was not available , but this analysis reflects possible additional assessment s ) , 5 ) 3 and 4 combined . Quality -of-life adjustments are made only on the basis of age , with an adjustment of 0.78 for life-years gained between the ages 65 and 74 years and an adjustment of 0.75 for life-years gained at ages older than 75 years ( 20 ) . The U.S.-specific estimates for scans ( initial and recall ) are based on Medicare reimbursement for AAA screening at $ 90.95 ( Current Procedural Terminology code G0389 ) ( 21 ) , and U.S.-specific costs for surgeries are based on previously published estimates ( 22 , 23 ) that were inflated to 2004 prices ( 24 ) : $ 18160 for elective procedures and $ 31106 for emergency procedures . Discounting is applied at the current recommended values of 3 % per annum for costs and effects ( 25 ) . Estimates of AAA-related costs and effects take into account the rate of nonAAA-related deaths across both groups over time . The Fieller method is used to calculate bounds for the CI for cost-effectiveness ( 26 , 27 ) . Role of the Funding Source This study was funded by the Medical Research Council . The funding source had no role in the design , implementation , or analysis of the study . Results Figure 1 shows the flow of participants through the trial . Numbers differ slightly from earlier publications because of identification of a few duplicate records in the data base . Of 67770 r and omly assigned men , 33883 were invited to be screened : 27204 ( 80 % ) attended and 1334 ( 4.9 % ) AAAs were identified . The mean age at r and omization was 69.2 years in both groups . Loss to follow-up because of death was 2.1 % overall ( 2.2 % in the control group and 2.1 % in the invited group ) . Loss to clinical follow-up ( nonattendance at recall scans ) was 19 % at 4 years and 24 % at 7 years . The Appendix Table shows surgeries and deaths within 30 days in each of the r and omly assigned groups . A few endovascular operations are included in these figures6 in the control group and 14 in the invited group . As expected , the total number of elective procedures is greater in the invited group than in the control group The natural history of the ectatic infrarenal aorta remains undetermined . While surveillance protocol s have been proposed for true aneurysms , no recommendations are currently available for ectatic aortas . The purpose of this study is to define the natural history and recommend surveillance protocol s for the infrarenal aorta 2.5 - 2.9 cm in diameter . Screening of 12,500 yielded 223 patients with an infrarenal abdominal aorta 2.5 - 2.9 cm in diameter at a university-affiliated VA medical center . All patients were prospect ively followed by ultrasound  from August 1993 through October 2000 and expansion rates were calculated by comparing the first and last study . Multivariate analysis of risk factors classically associated with abdominal aortic aneurysm was performed . Current data suggest that ectatic infrarenal aortas exp and slowly , do not rupture , and rarely meet criteria for operative repair . No risk factors linked to the development of aneurysms were identified . On the basis of this study we recommend that patients with ectatic aortas have a repeat ultrasound 5 years after the initial study BACKGROUND At present , several regions and countries are considering screening for abdominal aortic aneurysm ( AAA ) . However , The Chichester Aneurysms Screening Trial has reported poor long term benefit of screening for AAA . We therefore supplement previously published data with a preliminary analysis of the ten-year mortality from AAA , based upon population -based data until 2002 ( 7 years ) and incomplete hospital-based information on deaths until 2005 ( 10 years ) . METHODS AND MATERIAL In 1994 we started a r and omised screening trial of 12,639 64 - 73 year-old males ; 6,306 were controls , and 6,333 were invited to an abdominal ultrasound scan at their district hospital . Information on all deaths until 15.3.2005 was obtained from the Office of Civil Registration . Information on AAA related deaths was obtained from the national registry of Causes of Deaths from 1.4.1994 to 31.12.2001 , and supplemented with AAA deaths known to the Danish National Patient Registry until 15.3.2005 . Operations were obtained from the Danish National Vascular Registry from 1.4.1994 to 15.3.2005 . Death certificates and medical records were review ed by two independent assessors . The analyses were based on " intention to treat " from the date of r and omisation 
    Output:
    
Ultrasonography is noninvasive , can be conducted at a low cost , and does not involve radiation exposure .
When we pooled AAA-related mortality and screening harms , the summary effects showed high statistical heterogeneity at the longest follow-up .