Designing the Review

  • Spyridon N. Papageorgiou
  • Giuseppe Biondi-Zoccai


Overviews of systematic reviews are a relatively new research synthesis method that has emerged, due to the massive publication of systematic reviews and the need to answer complex clinical questions in a timely manner. Although the number of the overviews of systematic reviews has increased, no definitive guidelines regarding their conduct and reporting exist up to now. Some guidance regarding overview procedures can be, however, extrapolated from systematic review methodology, given the similarities that these two methods of evidence synthesis possess. On the other hand, considerable differences between overviews and systematic reviews exist regarding their scope, their eligibility criteria, and their analysis. It is therefore the aim of this chapter to provide a comprehensive guide through the steps of an overview of reviews, which will guide both interested readers and researchers willing to embark on such a journey themselves. This chapter’s main emphasis is given to the most widely known type of overview, the umbrella reviews, as the same principles apply to almost all overviews. Finally, specific considerations are given for the other main type of overviews of reviews, namely, meta-epidemiological studies.


Evidence-based medicine Evidence synthesis Meta-epidemiological study Overview of reviews Umbrella review 


  1. 1.
    Bastian H, Glasziou P, Chalmers I. Seventy-five trials and eleven systematic reviews a day: how will we ever keep up? PLoS Med. 2010;7:e1000326.PubMedCentralCrossRefPubMedGoogle Scholar
  2. 2.
    Hartling L, Chisholm A, Thomson D, Dryden DM. A descriptive analysis of overviews of reviews published between 2000 and 2011. PLoS One. 2012;7:e49667.PubMedCentralCrossRefPubMedGoogle Scholar
  3. 3.
    Khangura S, Konnyu K, Cushman R, Grimshaw J, Moher M. Evidence summaries: the evolution of a rapid review approach. Syst Rev. 2012;1:10.PubMedCentralCrossRefPubMedGoogle Scholar
  4. 4.
    Guirguis-Blake J, Calonge N, Miller T, Siu A, Teutsch S, Whitlock E. Current processes of the U.S. Preventive Services Task Force: refining evidence-based recommendation development. Ann Intern Med. 2007;147:117–22.CrossRefPubMedGoogle Scholar
  5. 5.
    Lavis JN. How can we support the use of systematic reviews in policymaking? PLoS Med Public Libr Sci. 2009;6:e1000141.CrossRefGoogle Scholar
  6. 6.
    Bambra C, Gibson M, Sowden AJ, Wright K, Whitehead M, Petticrew M. Working for health? Evidence from systematic reviews on the effects on health and health inequalities of organisational changes to the psychosocial work environment. Prev Med. 2009;48:454–61.CrossRefPubMedGoogle Scholar
  7. 7.
    Becker LA, Oxman AD. Chapter 22. Overview of reviews. In: Higgins JPT, Green S, editors. Cochrane handbook for systematic reviews of interventions version 5.1.0 [updated March 2011]. The Cochrane Collaboration; 2011. Available from
  8. 8.
    Ioannidis JP. Integration of evidence from multiple meta-analyses: a primer on umbrella reviews, treatment networks and multiple treatments meta-analyses. Can Med Assoc J. 2009;181:488–93.CrossRefGoogle Scholar
  9. 9.
    Biondi-Zoccai G, editor. Network meta-analysis: evidence synthesis with mixed treatment comparison. Hauppauge: Nova; 2014.Google Scholar
  10. 10.
    Sterne JA, Jüni P, Schulz KF, Altman DG, Bartlett C, Egger M. Statistical methods for assessing the influence of study characteristics on treatment effects in ‘meta-epidemiological’ research. Stat Med. 2002;21:1513–24.CrossRefPubMedGoogle Scholar
  11. 11.
    Stewart L, Moher D, Shekelle P. Why prospective registration of systematic reviews makes sense. Syst Rev. 2012;1:7.PubMedCentralCrossRefPubMedGoogle Scholar
  12. 12.
    Chalmers I, Bracken MB, Djulbegovic B, Garattini S, Grant J, Gülmezoglu AM, Howells DW, Ioannidis JP, Oliver S. How to increase value and reduce waste when research priorities are set. Lancet. 2014;383:156–65.CrossRefPubMedGoogle Scholar
  13. 13.
    Egger M, Juni P, Bartlett C, Holenstein F, Sterne J. How important are comprehensive literature searches and the assessment of trial quality in systematic reviews? Empirical study. Health Technol Assess. 2003;7:1–76.PubMedGoogle Scholar
  14. 14.
    Papageorgiou SN, Antonoglou G, Tsiranidou E, Jepsen S, Jäger A. Bias and small-study effects influence treatment effect estimates: a meta-epidemiological study in oral medicine. J Clin Epidemiol. 2014;67:984–92.CrossRefPubMedGoogle Scholar
  15. 15.
    Moher D, Pham B, Klassen TP, Schulz KF, Berlin JA, Jadad AR, Liberati A. What contributions do languages other than English make on the results of meta-analyses? J Clin Epidemiol. 2000;53:964–72.CrossRefPubMedGoogle Scholar
  16. 16.
    Jüni P, Holenstein F, Sterne J, Bartlett C, Egger M. Direction and impact of language bias in meta-analyses of controlled trials: empirical study. Int J Epidemiol. 2002;31:115–23.CrossRefPubMedGoogle Scholar
  17. 17.
    Panagiotou OA, Contopoulos-Ioannidis DG, Ioannidis JP. Comparative effect sizes in randomised trials from less developed and more developed countries: meta-epidemiological assessment. BMJ. 2013;346:f707.PubMedCentralCrossRefPubMedGoogle Scholar
  18. 18.
    Bowater RJ, Hartley LC, Lilford RJ. Are cardiovascular trial results systematically different between North America and Europe? A study based on intra-meta-analysis comparisons. Arch Cardiovasc Dis. 2015;108:23–38.CrossRefPubMedGoogle Scholar
  19. 19.
    Golder S, Loke YK, Bland M. Meta-analyses of adverse effects data derived from randomised controlled trials as compared to observational studies: methodological overview. PLoS Med. 2011;8:e1001026.PubMedCentralCrossRefPubMedGoogle Scholar
  20. 20.
    Tzoulaki I, Siontis KC, Ioannidis JP. Prognostic effect size of cardiovascular biomarkers in datasets from observational studies versus randomised trials: meta-epidemiology study. BMJ. 2011;343:d6829.PubMedCentralCrossRefPubMedGoogle Scholar
  21. 21.
    Papageorgiou SN, Xavier GM, Cobourne MT. Basic study design influences the results of orthodontic clinical investigations. J Clin Epidemiol. 2015. (Epub ahead of print). doi: 10.1016/j.jclinepi.2015.03.008.
  22. 22.
    Nüesch E, Trelle S, Reichenbach S, Rutjes AW, Tschannen B, Altman DG, Egger M, Jüni P. Small study effects in meta-analyses of osteoarthritis trials: meta-epidemiological study. BMJ. 2010;341:c3515.PubMedCentralCrossRefPubMedGoogle Scholar
  23. 23.
    Chaimani A, Vasiliadis HS, Pandis N, Schmid CH, Welton NJ, Salanti G. Effects of study precision and risk of bias in networks of interventions: a network meta-epidemiological study. Int J Epidemiol. 2013;42:1120–31.CrossRefPubMedGoogle Scholar
  24. 24.
    Dechartres A, Trinquart L, Boutron I, Ravaud P. Influence of trial sample size on treatment effect estimates: meta-epidemiological study. BMJ. 2013;346:f2304.PubMedCentralCrossRefPubMedGoogle Scholar
  25. 25.
    Savović J, Jones H, Altman D, Harris R, Jűni P, Pildal J, Als-Nielsen B, Balk E, Gluud C, Gluud L, Ioannidis J, Schulz K, Beynon R, Welton N, Wood L, Moher D, Deeks J, Sterne J. Influence of reported study design characteristics on intervention effect estimates from randomised controlled trials: combined analysis of meta-epidemiological studies. Health Technol Assess. 2012;16:1–82.PubMedGoogle Scholar
  26. 26.
    Turner R, Spiegelhalter D, Smith G, Thompson S. Bias modelling in evidence synthesis. J R Stat Soc Ser A Stat Soc. 2009;172:21–47.PubMedCentralCrossRefPubMedGoogle Scholar
  27. 27.
    Welton N, Ades A, Carlin J, Altman D, Sterne J. Models for potentially biased evidence in meta-analysis using empirically based priors. J R Stat Soc Ser A. 2009;172:119e36.CrossRefGoogle Scholar
  28. 28.
    Biondi-Zoccai GG, Lotrionte M, Abbate A, Testa L, Remigi E, Burzotta F, Valgimigli M, Romagnoli E, Crea F, Agostoni P. Compliance with QUOROM and quality of reporting of overlapping meta-analyses on the role of acetylcysteine in the prevention of contrast associated nephropathy: case study. BMJ. 2006;332:202–9.PubMedCentralCrossRefPubMedGoogle Scholar
  29. 29.
    Panic N, Leoncini E, de Belvis G, Ricciardi W, Boccia S. Evaluation of the endorsement of the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement on the quality of published systematic review and meta-analyses. PLoS One. 2013;8:e83138.PubMedCentralCrossRefPubMedGoogle Scholar
  30. 30.
    Papageorgiou SN, Papadopoulos MA, Athanasiou AE. Evaluation of methodology and quality characteristics of systematic reviews in orthodontics. Orthod Craniofac Res. 2011;14:116–37.CrossRefPubMedGoogle Scholar
  31. 31.
    Tunis AS, McInnes MD, Hanna R, Esmail K. Association of study quality with completeness of reporting: have completeness of reporting and quality of systematic reviews and meta-analyses in major radiology journals changed since publication of the PRISMA statement? Radiology. 2013;269:413–26.CrossRefPubMedGoogle Scholar
  32. 32.
    Papageorgiou SN, Papadopoulos MA, Athanasiou AE. Reporting characteristics of meta-analyses in orthodontics: methodological assessment and statistical recommendations. Eur J Orthod. 2014;36:74–85.CrossRefPubMedGoogle Scholar
  33. 33.
    Papageorgiou SN, Papadopoulos MA, Athanasiou AE. Assessing small study effects and publication bias in orthodontics: a meta-epidemiological study. Clin Oral Investig. 2014;18:1031–44.CrossRefPubMedGoogle Scholar
  34. 34.
    Onishi A, Furukawa TA. Publication bias is underreported in systematic reviews published in high-impact-factor journals: metaepidemiologic study. J Clin Epidemiol. 2014;67:1320–6.CrossRefPubMedGoogle Scholar
  35. 35.
    Papageorgiou SN, Dimitraki D, Coolidge T, Kotsanos N. Publication bias & small-study effects in pediatric dentistry meta-analyses. J Evid Based Dent Pract. 2015;15:8–24.CrossRefPubMedGoogle Scholar
  36. 36.
    Seida JK, Ospina MB, Karkhaneh M, Hartling L, Smith V, Clark B. Systematic reviews of psychosocial interventions for autism: an umbrella review. Dev Med Child Neurol. 2009;51:95–104.CrossRefPubMedGoogle Scholar
  37. 37.
    Cipriani A, Higgins JP, Geddes JR, Salanti G. Conceptual and technical challenges in network meta-analysis. Ann Intern Med. 2013;159:130–7.CrossRefPubMedGoogle Scholar
  38. 38.
    Schünemann HJ, Tugwell P, Reeves BC, Ekl EA, Santesso N, Spencer FA, Shea B, Wells G, Helfand M. Non-randomized studies as a source of complementary, sequential, or replacement evidence for randomized controlled trials in systematic reviews on the effects of interventions. Res Synth Methods. 2013;4:49–62.CrossRefPubMedGoogle Scholar
  39. 39.
    Pieper D, Antoine SL, Neugebauer EA, Eikermann M. Up-to-dateness of reviews is often neglected in overviews: a systematic review. J Clin Epidemiol. 2014;67:1302–8.CrossRefPubMedGoogle Scholar
  40. 40.
    Moher D, Tsertsvadze A, Tricco AC, Eccles M, Grimshaw J, Sampson M, Barrowman N. When and how to update systematic reviews. Cochrane Database Syst Rev. 2008;(1):MR000023.Google Scholar
  41. 41.
    Pattanittum P, Laopaiboon M, Moher D, Lumbiganon P, Ngamjarus C. A comparison of statistical methods for identifying out-of-date systematic reviews. PLoS One. 2012;7:e48894.PubMedCentralCrossRefPubMedGoogle Scholar
  42. 42.
    Shojania KG, Sampson M, Ansari MT, Ji J, Doucette S, Moher D. How quickly do systematic reviews go out of date? A survival analysis. Ann Intern Med. 2007;147:224–33.CrossRefPubMedGoogle Scholar
  43. 43.
    Pieper D, Buechter R, Jerinic P, Eikermann M. Overviews of reviews often have limited rigor: a systematic review. J Clin Epidemiol. 2012;65:1267–73.CrossRefPubMedGoogle Scholar
  44. 44.
    Hunt DL, McKibbon KA. Locating and appraising systematic reviews. Ann Intern Med. 1997;126:532–8.CrossRefPubMedGoogle Scholar
  45. 45.
    Shojania KG, Bero LA. Taking advantage of the explosion of systematic reviews: an efficient MEDLINE search strategy. Eff Clin Pract. 2001;4:157–62.PubMedGoogle Scholar
  46. 46.
    Montori VM, Wilczynski NL, Morgan D, Haynes RB; Hedges Team. Optimal search strategies for retrieving systematic reviews from Medline: analytical survey. BMJ. 2005;330:68.Google Scholar
  47. 47.
    Wilczynski NL, Haynes RB. EMBASE search strategies achieved high sensitivity and specificity for retrieving methodologically sound systematic reviews. J Clin Epidemiol. 2007;60:29–33.CrossRefPubMedGoogle Scholar
  48. 48.
    Lee E, Dobbins M, Decorby K, McRae L, Tirilis D, Husson H. An optimal search filter for retrieving systematic reviews and metaanalyses. BMC Med Res Methodol. 2012;12:51.PubMedCentralCrossRefPubMedGoogle Scholar
  49. 49.
    Dickersin K, Scherer R, Lefebvre C. Identifying relevant studies for systematic reviews. BMJ. 1994;309:1286–91.PubMedCentralCrossRefPubMedGoogle Scholar
  50. 50.
    Whiting P, Westwood M, Burke M, Sterne J, Glanville J. Systematic reviews of test accuracy should search a range of databases to identify primary studies. J Clin Epidemiol. 2008;61:357–64.CrossRefPubMedGoogle Scholar
  51. 51.
    Petticrew M, Song F, Wilson P, Wright K. Quality-assessed reviews of health care interventions and the database of abstracts of reviews of effectiveness (DARE). Int J Technol Assess Health Care. 1999;15:671–8.PubMedGoogle Scholar
  52. 52.
    Smith V, Devane D, Begley C, Clarke M. Methodology in conducting a systematic review of systematic reviews of healthcare interventions. BMC Med Res Methodol. 2011;211:11–5.Google Scholar
  53. 53.
    Rathbone J, Carter M, Hoffmann T, Glasziou P. Better duplicate detection for systematic reviewers: evaluation of Systematic Review Assistant-Deduplication Module. Syst Rev. 2015;4:6.PubMedCentralCrossRefPubMedGoogle Scholar
  54. 54.
    Qi X, Yang M, Ren W, Jia J, Wang J, Han G, Fan D. Find duplicates among the PubMed, EMBASE, and Cochrane library databases in systematic review. PLoS One. 2013;8:e71838.PubMedCentralCrossRefPubMedGoogle Scholar
  55. 55.
    Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JP, Clarke M, Devereaux PJ, Kleijnen J, Moher D. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. J Clin Epidemiol. 2009;62:e1–34.CrossRefPubMedGoogle Scholar
  56. 56.
    Higgins JP, Altman DG, Gøtzsche PC, Jüni P, Moher D, Oxman AD, Savovic J, Schulz KF, Weeks L, Sterne JA; Cochrane Bias Methods Group; Cochrane Statistical Methods Group. The Cochrane Collaboration’s tool for assessing risk of bias in randomized trials. BMJ. 2011;343:d5928.Google Scholar
  57. 57.
    Deeks JJ, Dinnes J, D’Amico R, Sowden AJ, Sakarovitch C, Song F, Petticrew M, Altman DG; International Stroke Trial Collaborative Group; European Carotid Surgery Trial Collaborative Group. Evaluating non-randomised intervention studies. Health Technol Assess. 2003;7:iii–x, 1–173.Google Scholar
  58. 58.
    Downs SH, Black N. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health. 1998;52:377–84.PubMedCentralCrossRefPubMedGoogle Scholar
  59. 59.
    Wells G, Shea B, O’Connell D, Peterson J, Welch V, Losos M, Tugwell P. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomized studies in meta-analyses. Available from: Accessed 24 Mar 2014.
  60. 60.
    Oxman AD, Guyatt GH. Validation of an index of the quality of review articles. J Clin Epidemiol. 1991;44:1271–8.CrossRefPubMedGoogle Scholar
  61. 61.
    Shea BJ, Grimshaw JM, Wells GA, Boers M, Andersson N, Hamel C, Porter AC, Tugwell P, Moher D, Bouter LM. Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews. BMC Med Res Methodol. 2007;7:10.PubMedCentralCrossRefPubMedGoogle Scholar
  62. 62.
    Moher D, Cook DJ, Eastwood S, Olkin I, Rennie D, Stroup DF; for the QUOROM Group. Improving the quality of reports of meta-analyses of randomised controlled trials: the QUOROM statement. Lancet. 1999;354:1896–900.Google Scholar
  63. 63.
    Glenny AM, Esposito M, Coulthard P, Worthington HV. The assessment of systematic reviews in dentistry. Eur J Oral Sci. 2003;111:85–92.CrossRefPubMedGoogle Scholar
  64. 64.
    Guyatt G, Rennie D. Users’ guides to medical literature: a manual for evidence-based clinical practice. Chicago: American Medical Association; 2002.Google Scholar
  65. 65.
    The Joanna Briggs Institute. Rapid appraisal protocol internet database. Rapid user guide 1.2. Adelaide: The Joanna Briggs Institute; 2006.Google Scholar
  66. 66.
    Task Force on Systematic Review and Guidelines. Guidelines for assessing the quality and applicability of systematic reviews. Austin: National Center for the Dissemination of Disability Research; 2011. Available at: Scholar
  67. 67.
    Shea B, Dube C, Moher D. Assessing the quality of reports of systematic reviews: the QUORUM statement compared to other tools. In: Egger M, Smith GD, Altman DG, editors. Systematic reviews in health care: meta-analysis in context. London: BMJ Publishing Group; 2001. p. 122–39.CrossRefGoogle Scholar
  68. 68.
    Oxman AD, Schunemann HJ, Fretheim A. Improving the use of research evidence in guideline development: 8. Synthesis and presentation of evidence. Health Res Policy Syst. 2006;4:20.PubMedCentralCrossRefPubMedGoogle Scholar
  69. 69.
    Canadian Coordinating Office of Health Technology Assessment. COMPUS procedure. Evidence-based best practice recommendations. Available: Accessed 28 Mar 2015.
  70. 70.
    Higgins JPT, Lane PW, Anagnostelis B, Anzures-Cabrera J, Baker NF, Cappelleri JC, Haughie S, Hollis S, Lewis SC, Moneuse P, Whitehead A. A tool to assess the quality of a meta-analysis. Res Synth Methods. 2013;4:351–66.CrossRefPubMedGoogle Scholar
  71. 71.
    Papageorgiou SN. Meta-analysis for orthodontists: part II – is all that glitters gold? J Orthod. 2014;41:327–36.CrossRefPubMedGoogle Scholar
  72. 72.
    Guyatt GH, Oxman AD, Schünemann HJ, Tugwell P, Knottnerus A. GRADE guidelines: a new series of articles in the Journal of Clinical Epidemiology. J Clin Epidemiol. 2011;64:380–2.CrossRefPubMedGoogle Scholar
  73. 73.
    Chinn S. A simple method for converting an odds ratio to effect size for use in meta-analysis. Stat Med. 2000;19:3127–31.CrossRefPubMedGoogle Scholar
  74. 74.
    Contopoulos-Ioannidis DG, Ioannidis JP. Claims for improved survival from systemic corticosteroids in diverse conditions: an umbrella review. Eur J Clin Invest. 2012;42:233–44.CrossRefPubMedGoogle Scholar
  75. 75.
    Theodoratou E, Tzoulaki I, Zgaga L, Ioannidis JP. Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational studies and randomised trials. BMJ. 2014;348:g2035.PubMedCentralCrossRefPubMedGoogle Scholar
  76. 76.
    Papageorgiou SN. Meta-analysis for orthodontists: part I--how to choose effect measure and statistical model. J Orthod. 2014;41:317–26.CrossRefPubMedGoogle Scholar
  77. 77.
    Belbasis L, Bellou V, Evangelou E, Ioannidis JP, Tzoulaki I. Environmental risk factors and multiple sclerosis: an umbrella review of systematic reviews and meta-analyses. Lancet Neurol. 2015;14:263–73.CrossRefPubMedGoogle Scholar
  78. 78.
    Tsilidis KK, Kasimis JC, Lopez DS, Ntzani EE, Ioannidis JP. Type 2 diabetes and cancer: umbrella review of meta-analyses of observational studies. BMJ. 2015;350:g7607.CrossRefPubMedGoogle Scholar
  79. 79.
    Shrier I, Platt RW, Steele RJ. Mega-trials vs. meta-analysis: precision vs. heterogeneity? Contemp Clin Trials. 2007;28:324–8.CrossRefPubMedGoogle Scholar
  80. 80.
    Inthout J, Ioannidis JP, Borm GF. Obtaining evidence by a single well-powered trial or several modestly powered trials. Stat Methods Med Res. 2012. [Epub ahead of print].Google Scholar
  81. 81.
    Biondi-Zoccai G, Peruzzi M, Frati G. Commentary: which do you like better…a bowl of Cheerios or a Big Mac? Pros and cons of meta-analyses in endovascular research. J Endovasc Ther. 2013;20:145–8.CrossRefPubMedGoogle Scholar
  82. 82.
    Egger M, Davey Smith G, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ. 1997;315:629–34.PubMedCentralCrossRefPubMedGoogle Scholar
  83. 83.
    Harbord RM, Egger M, Sterne JA. A modified test for small-study effects in meta-analyses of controlled trials with binary endpoints. Stat Med. 2006;25:3443–57.CrossRefPubMedGoogle Scholar
  84. 84.
    Peters JL, Sutton AJ, Jones DR, Abrams KR, Rushton L. Comparison of two methods to detect publication bias in meta-analysis. JAMA. 2006;295:676–80.CrossRefPubMedGoogle Scholar
  85. 85.
    Ioannidis JP, Trikalinos TA. An exploratory test for an excess of significant findings. Clin Trials. 2007;4:245–53.CrossRefPubMedGoogle Scholar
  86. 86.
    Ioannidis J. Clarifications on the application and interpretation of the test for excess significance and its extensions. J Math Psychol. 2013;57:184–7.CrossRefGoogle Scholar
  87. 87.
    Strech D, Tilburt J. Value judgments in the analysis and synthesis of evidence. J Clin Epidemiol. 2008;61:521–4.CrossRefPubMedGoogle Scholar
  88. 88.
    Whitlock EP, Lin JS, Chou R, Shekelle P, Robinson KA. Using existing systematic reviews in complex systematic reviews. Ann Intern Med. 2008;148:776–82.CrossRefPubMedGoogle Scholar
  89. 89.
    Jadad AR, Cook DJ, Browman GP. A guide to interpreting discordant systematic reviews. CMAJ. 1997;156:1411–6.PubMedCentralPubMedGoogle Scholar
  90. 90.
    Lu G, Ades AE. Combination of direct and indirect evidence in mixed treatment comparisons. Stat Med. 2004;23:3105–24.CrossRefPubMedGoogle Scholar
  91. 91.
    Glenny AM, Altman DG, Song F, Sakarovitch C, Deeks JJ, D’Amico R, Bradburn M, Eastwood AJ. Indirect comparisons of competing interventions. Health Technol Assess. 2005;9:26.CrossRefGoogle Scholar
  92. 92.
    Thomson D, Russell K, Becker L, Klassen T, Hartling L. The evolution of a new publication type: steps and challenges of producing overviews of reviews. Res Synth Methods. 2010;1:198–211.CrossRefPubMedGoogle Scholar

Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  • Spyridon N. Papageorgiou
    • 1
    • 2
  • Giuseppe Biondi-Zoccai
    • 3
    • 4
  1. 1.Department of Orthodontics, School of DentistryUniversity of BonnBonnGermany
  2. 2.Department of Oral Technology, School of DentistryUniversity of BonnBonnGermany
  3. 3.Department of Medico-Surgical Sciences and BiotechnologiesSapienza University of RomeLatinaItaly
  4. 4.Eleonora Lorillard Spencer Cenci FoundationRomeItaly

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