Janelle M. Guirguis-Blake, MD; Tracy L. Beil, MS; Caitlyn A. Senger, MPH; Evelyn P. Whitlock, MD, MPH
Note: This review was conducted by the Kaiser Permanente Research Affiliates Evidence-based Practice Center under contract to AHRQ. AHRQ staff provided oversight for the project and assisted in the external review of the companion draft evidence synthesis.
Disclaimer: The authors of this article are responsible for its content. Statements in the article should not be construed as endorsements by AHRQ or the U.S. Department of Health and Human Services.
Acknowledgment: The authors thank the following persons for their contributions to this project: Jennifer Croswell, MD, MPH, and Tracy Wolff, MD, MPH, at AHRQ; Kirsten Bibbins-Domingo, MD, PhD, Mark Ebell, MD, MS, Jessica Herzstein, MD, MPH, and Albert Siu, MD, MSPH, of the USPSTF; and Jonathan Fine, MFA, Maya Rowland, MPH, Brittany Burda, MPH, Corinne Evans, MPP, and Xin Sun, PhD, at the Kaiser Permanente Center for Health Research.
Financial Support: By AHRQ (contract HHS-290-2007-10057-I).
Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M13-1844.
Requests for Single Reprints: Reprints are available from the AHRQ Web site (www.ahrq.gov).
Current Author Addresses: Dr. Guirguis-Blake: University of Washington, Department of Family Medicine, Tacoma Family Medicine Residency Program, 521 Martin Luther King Jr. Way, Tacoma, WA 98405.
Dr. Whitlock, Ms. Beil, and Ms. Senger: Kaiser Permanente Center for Health Research, 3800 North Interstate Avenue, Portland, OR 97227.
Author Contributions: Conception and design: J.M. Guirguis-Blake, T.L. Beil, C.A. Senger, E.P. Whitlock.
Analysis and interpretation of the data: J.M. Guirguis-Blake, T.L. Beil, C.A. Senger, E.P. Whitlock.
Drafting of the article: J.M. Guirguis-Blake, C.A. Senger, E.P. Whitlock.
Critical revision of the article for important intellectual content: J.M. Guirguis-Blake, T.L. Beil, C.A. Senger, E.P. Whitlock.
Final approval of the article: J.M. Guirguis-Blake, T.L. Beil, C.A. Senger, E.P. Whitlock.
Provision of study materials or patients: T.L. Beil.
Obtaining of funding: E.P. Whitlock.
Administrative, technical, or logistic support: J.M. Guirguis-Blake, T.L. Beil, C.A. Senger.
Collection and assembly of data: J.M. Guirguis-Blake, T.L. Beil, C.A. Senger, E.P. Whitlock.
Long-term follow-up of population-based randomized, controlled trials (RCTs) has demonstrated that screening for abdominal aortic aneurysms (AAAs) measuring 3 cm or greater decreases AAA-related mortality rates in men aged 65 years or older.
To systematically review evidence about the benefits and harms of ultrasonography screening for AAAs in asymptomatic primary care patients.
MEDLINE, the Database of Abstracts of Reviews of Effects, the Cochrane Central Register of Controlled Trials (January 2004 through January 2013), clinical trial registries, reference lists, experts, and a targeted bridge search for population-based screening RCTs through September 2013.
English-language, population-based, fair- to good-quality RCTs and large cohort studies for AAA screening benefits as well as RCTs and cohort and registry studies for harms in adults with AAA.
Dual quality assessment and abstraction of study details and results.
Reviews of 4 RCTs involving 137 214 participants demonstrated that 1-time invitation for AAA screening in men aged 65 years or older reduced AAA rupture and AAA-related mortality rates for up to 10 and 15 years, respectively, but had no statistically significant effect on all-cause mortality rates up to 15 years. Screening was associated with more overall and elective surgeries but fewer emergency operations and lower 30-day operative mortality rates at up to 10- to 15-year follow-up. One RCT involving 9342 women showed that screening had no benefit on AAA-related or all-cause mortality rates.
Trials included mostly white men outside of the United States. Information for subgroups and about rescreening was limited.
One-time invitation for AAA screening in men aged 65 years or older was associated with decreased AAA rupture and AAA-related mortality rates but had little or no effect on all-cause mortality rates.
Agency for Healthcare Research and Quality.
Analytic framework and key questions.
AAA = abdominal aortic aneurysm; COPD = chronic obstructive pulmonary disease; EVAR = endovascular aneurysm repair; QOL = quality of life.
Summary of evidence search and selection.
AAA = abdominal aortic aneurysm; KQ = key question.
* Evidence related to the treatment of small AAAs is included in the full evidence report (22).
† One study was excluded for study design and outcomes.
Table 1. Methodological and Intervention Characteristics of the 4 Included Population-Based AAA Screening Randomized, Controlled Trials
Table 2. All-Cause and AAA-Related Mortality Data for 1-Time Screening Trials at the Initial and Longest Follow-up
Downstream events in 1-time abdominal aortic aneurysm screening trials at longest follow-up.
RR = risk ratio.
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Lars Beckmann, Sibylle Sturtz, Julia Kreis, Ralf Bender, Milly Schröer-Günther
Institute for Quality and Efficiency in Health Care (IQWiG), 50670, Cologne, Germany
July 16, 2015
Why precise reporting of statistical analyses is essential – A case report of a systematic review
Both the German Institute for Quality and Efficiency in Health Care (IQWiG) (1) and the U.S. Preventive Services Task Force (USPSTF) (2, 3) have recently published systematic reviews (SRs) on screening for abdominal aortic aneurysm (AAA); both determined a net benefit in men aged 65-75 years. The recommendations were based on positive findings for AAA-specific mortality, ruptures and emergency surgery, which were not outweighed by harm from elective surgery. However, regarding all-cause mortality, contradictory conclusions were drawn, even though both reviews used the same data from 4 large randomized controlled trials (RCTs) and the same primary statistical analysis method.IQWiG determined a statistically significant result for all-cause mortality in terms of the odds ratio after 13-15 years of follow-up, applying the prespecified DerSimonian and Laird method for random effects meta-analysis (1). The risk ratio was RR=0.985 (95% confidence interval (CI) [0.971, 0.999]; p=0.042). IQWiG thus concluded that screening provides a benefit with respect to all-cause mortality (1).Using the same data and method, USPSTF determined an RR of 0.98 (95% CI [0.97, 1.00]) for 13-15 years of follow-up (3). The results were identical to those of IQWiG. However, the numbers were rounded to 2 digits and thus appeared to be non-significant based on the CI. Moreover, p-values were not provided. Similar discrepancies exist for the 10-year follow-up data. In the accompanying publication, the authors additionally conducted 2 sensitivity analyses for the 13-15 year follow-up data, applying a prespecified fixed effect model as well as a profile likelihood method specified post hoc (2). Details of the latter method were not provided. The authors stated that the results produced by all of the 3 methods were identical and not statistically significant, and finally concluded that AAA screening has no benefit with respect to all-cause mortality (2). However, in line with the random effects model, at least the result of the fixed effect model is statistically significant (p=0.042).The USPSTF conclusion has consequences: The results for all-cause mortality were interpreted as being non-significant and the potential benefit of screening might have been underestimated (4). Furthermore, the positive finding for all-cause mortality was not considered in patient information or clinical guidelines (5). In summary, results of statistical analyses included in SRs should always be reported precisely and the conclusions drawn should exactly reflect the results. Otherwise, reporting inaccuracies may affect not only the conclusions of the SR itself, but also those of subsequent publications. References1. Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen. Ultraschall-Screening auf Bauchaortenaneurysmen: Abschlussbericht; Auftrag S13-04; Version 1.1. 2 April 2015. Accessed at https://www.iqwig.de/download/S13-04_Abschlussbericht_Version1-1_Ultraschall-Screening-auf-Bauchaortenaneurysmen.pdf on 22 June 2015. 2. Guirguis-Blake JM, Beil TL, Senger CA, Whitlock EP. Ultrasonography screening for abdominal aortic aneurysms: a systematic evidence review for the U.S. Preventive Services Task Force. Ann Intern Med. 2014;160(5):321-9. [PMID: 24473919]3. Guirguis-Blake JM, Beil TL, Sun X, Senger CA, Whitlock EP. Primary care screening for abdominal aortic aneurysm: a systematic evidence review for the U.S. Preventive Services Task Force; AHRQ publication no 14-05202-EF-1. January 2014. Accessed at http://www.ncbi.nlm.nih.gov/books/NBK184793/pdf/TOC.pdf on 10 April 2014. [PMID: 24555205]4. Johansson M, Hansson A, Brodersen J. Estimating overdiagnosis in screening for abdominal aortic aneurysm: could a change in smoking habits and lowered aortic diameter tip the balance of screening towards harm? BMJ. 2015;350:h825. [PMID: 25736421]5. LeFevre ML, US Preventive Serv Task Force. Screening for abdominal aortic aneurysm: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2014;161(4):281-90. [PMID: 24957320]
Guirguis-Blake JM, Beil TL, Senger CA, Whitlock EP. Ultrasonography Screening for Abdominal Aortic Aneurysms: A Systematic Evidence Review for the U.S. Preventive Services Task Force. Ann Intern Med. ;160:321–329. doi: 10.7326/M13-1844
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Published: Ann Intern Med. 2014;160(5):321-329.
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