Background
Methods
Design and sample
Data extraction
Data analysis
Results
Number of meta-analyses
General characteristics of the sample
Characteristic | Number (%) |
---|---|
Total number of articles | 736 (100) |
Articles per journala
| |
BMJ
| 289 (39.3) |
The Lancet
| 132 (17.9) |
JAMA
| 113 (15.3) |
Arch Intern Med
| 112 (15.2) |
Ann Intern Med
| 70 (9.5) |
New Engl J Med
| 13 (1.8) |
PLoS Med
| 7 (0.9) |
Citations per journalb
| |
BMJ
| 37,930 (29.0) |
The Lancet
| 34,911 (26.7) |
JAMA
| 25,273 (19.3) |
Ann Intern Med
| 13,381 (10.2) |
Arch Intern Med
| 11,945 (9.1) |
New Engl J Med
| 6,992 (5.3) |
PLoS Med
| 212 (0.1) |
Articles per period of publication | |
1985 to 1989 | 3 (0.4) |
1990 to 1994 | 53 (7.2) |
1995 to 1999 | 140 (19.0) |
2000 to 2004 | 166 (22.6) |
2005 to 2009 | 231 (31.4) |
2010 to 2012 | 143 (19.4) |
Country of publication (first author)c
| |
USA | 214 (29.1) |
UK | 207 (28.1) |
Canada | 94 (12.8) |
Australia | 36 (4.9) |
Switzerland | 26 (3.5) |
France | 26 (3.5) |
Denmark | 20 (2.7) |
Italy | 20 (2.7) |
Number of authors per paper | |
1 | 41 (5.6) |
2 to 3 | 166 (22.5) |
4 to 6 | 297 (40.3) |
> 7 | 232 (31.5) |
Production and collaboration patterns
Author | Primary affiliation at the time of publication | Year of first eligible paper | Total papers, n | Signatures, n | Collaborations, n | Main collaborators (number of papers) |
---|---|---|---|---|---|---|
Lau, Joseph | Brown University, USAa
| 1992 | 15 | 90 | 54 | Chalmers TC and Ioannidis JPA (5) |
Guyatt, Gordon H | McMaster University, Canada | 1996 | 14 | 104 | 76 | Cook DJ (5) |
Peto, Richard | University of Oxford, UK | 1991 | 13 | 124 | 75 | Collins R (8) |
Yusuf, Salim | McMaster University, Canada | 1989 | 12 | 83 | 54 | Collins R, Eikelboom JW, Mehta SR and Pogue J (3) |
Cook, Deborah J | McMaster University, Canada | 1995 | 11 | 71 | 49 | Guyatt GH (5) |
Jüni, Peter | University of Bern, Switzerland | 1996 | 11 | 124 | 59 | Reichenbach S (8) |
Collins, Rory | University of Oxford, UK | 1991 | 9 | 78 | 45 | Peto R (8) |
Trelle, Sven | University of Bern, Switzerland | 2007 | 9 | 103 | 67 | Jüni P and Reichenbach S (7) |
Bucher, Heiner C | University Hospital Basel, Switzerland | 1996 | 8 | 60 | 41 | Guyatt GH (4) |
Egger, Mathias | University of Bern, Switzerland | 2001 | 8 | 65 | 49 | Jüni P, Reichenbach S and Trelle S (3) |
Gluud, Christian | Copenhagen University Hospital, Denmark | 2001 | 8 | 40 | 21 | Wetterslev J (3) |
Gøtzsche, Peter C | The Nordic Cochrane Centre, Denmark | 1995 | 8 | 27 | 17 | Johansen HK (3) |
Jackson, Jeffrey L | Zablocki VA Medical Center, USA | 1997 | 8 | 33 | 23 | Browning R and O’Malley Patrick G (2) |
Law, Malcolm R | Queen Mary University of London, UK | 1991 | 8 | 24 | 7 | Wald NJ (8) |
Reichenbach, Stephan | University of Bern, Switzerland | 2004 | 8 | 81 | 44 | Jüni P (8) |
Sutton, Alex J | University of Leicester, UK | 2003 | 8 | 40 | 28 | Cooper NJ (3) |
Suttorp, Maarten J | St Antonius Hospital, the Netherlands | 2003 | 8 | 120 | 61 | Maglione M, Mojica WA, Morton SC and Shekelle PG (5) |
Wald, Nicholas J | Queen Mary University of London, UK | 1991 | 8 | 24 | 7 | Law MR (8) |
Clarke, Michael | University of Oxford, UK | 1994 | 7 | 83 | 67 | Peto R (4) |
Furberg, Curt D | Wake Forest University School of Medicine, USA | 1989 | 7 | 36 | 20 | Loke YK, Psaty BM and Singh S (3) |
Baigent, Colin | University of Oxford, UK | 1996 | 6 | 50 | 26 | Collins R and Peto R (5) |
Boersma, Eric | Erasmus Medical Center, the Netherlands | 2001 | 6 | 74 | 63 | Califf RM, Serruys P, Simes J, Simoons ML and Topol EJ (2) |
Boissel, Jean-Pierre | Université Claude Bernard Lyon 1, France | 1992 | 6 | 42 | 26 | Fagard RH and Gueyffier F (3) |
Chalmers, Thomas C | Tufts Medical Center, Tufts University, USA | 1990 | 6 | 31 | 16 | Lau J (5) |
Douketis, James D | McMaster University, Canada | 2000 | 6 | 32 | 25 | Crowther MA (2) |
Ebrahim, Shah | London School of Hygiene and Tropical Medicine, UK | 1997 | 6 | 70 | 60 | Smith GD (4) |
Ioannidis, John PA | Stanford University, USA | 1995 | 6 | 32 | 17 | Lau J (5) |
Khan, Khalid S | Queen Mary University of London, UK | 1996 | 6 | 39 | 27 | Bhattacharya S, Champaneria R, Cooper K, Jolly K and Middleton LJ (2) |
Klassen, Terry P | University of Manitoba, Canada | 1996 | 6 | 48 | 36 | Moher D (3) |
Loke, Yoon K | University of East Anglia, UK | 2000 | 6 | 18 | 7 | Singh S (4) |
McAlister, Finlay A | University of Alberta, Canada | 2001 | 6 | 30 | 23 | Armstrong PW (2) |
Moher, David | Ottawa Hospital Research Institute, Canada | 1996 | 6 | 52 | 42 | Klassen TP (3) |
Roberts, Ian | London School of Hygiene and Tropical Medicine, UK | 1996 | 6 | 18 | 12 | All co-authorship (1) |
Sattar, Naveed | University of Glasgow, UK | 2009 | 6 | 91 | 58 | Ray KK and Seshasai SRK (5) |
Shekelle, Paul G | Rand Corporation, USA | 2003 | 6 | 57 | 29 | Maglione M, Mojica WA, Morton SC and Suttorp MJ (5) |
Stone, Gregg W | Columbia University Medical Center, USA | 2005 | 6 | 120 | 77 | Leon MB (4) |
Tognoni, Gianni | Consorzio Mario Negri Sud, Italy | 1993 | 6 | 78 | 69 | Marchioli R, Marfisi RM and Roncaglioni MC (2) |
Topol, Eric J | Scripps Translational Science Institute, USA | 1991 | 6 | 44 | 33 | Boersma E, Califf RM, Simoons ML, Tcheng JE and Van de Werf F (2) |
Bischoff Ferrari, Heike A | University Hospital Zurich, Switzerland | 2004 | 5 | 48 | 26 | Dawson Hughes B, Staehelin HB, Willett WC and Wong JB (4) |
Briel, Matthias | University Hospital Basel, Switzerland | 2006 | 5 | 51 | 43 | Bucher HC (3) |
Eikelboom, John W | McMaster University, Canada | 2000 | 5 | 19 | 10 | Yusuf S (3) |
Ernst, Edzard | University of Exeter, UK | 1995 | 5 | 18 | 11 | White AR (3) |
Fagard, Robert H | University of Leuven, Belgium | 1997 | 5 | 51 | 36 | Boissel JP and Gueyffier F (3) |
Fergusson, Dean | Ottawa Hospital Research Institute, Canada | 1998 | 5 | 33 | 22 | Hutton B (3) |
Glasziou, Paul | Bond University, Australia | 1993 | 5 | 26 | 21 | All co-authorship (1) |
Godwin, Jon | Glasgow Caledonian University, UK | 1995 | 5 | 52 | 38 | Peto R (4) |
Gray, Richard | University of Oxford, UK | 2001 | 5 | 48 | 36 | Clarke M and Peto R (3) |
Hennekens, Charles H | Florida Atlantic University, USA | 1995 | 5 | 28 | 19 | Hebert, PR (4) |
Leibovici, Leonard | Rabin Medical Center, Israel | 2003 | 5 | 22 | 12 | Paul M (5) |
Maglione, Margaret | Rand Corporation, USA | 2003 | 5 | 49 | 22 | Mojica WA, Morton SC, Shekelle PG and Suttorp MJ (5) |
Mojica, Walter A | Rand Corporation, USA | 2003 | 5 | 49 | 22 | Maglione M, Morton SC, Shekelle PG, and Suttorp MJ (5) |
Morton, Sally C | University of Pittsburgh, USA | 2003 | 5 | 49 | 22 | Maglione M, Mojica WA, Shekelle PG and Suttorp MJ (5) |
Nüesch, Eveline | University of Bern, Switzerland | 2009 | 5 | 35 | 16 | Jüni P (5) |
Paul, Mical | Rabin Medical Center, Beilinson Hospital, Israel | 2003 | 5 | 22 | 12 | Leibovici L (5) |
Pignon, Jean-Pierre | Institut Gustave-Roussy, France | 1999 | 5 | 53 | 46 | Bourhis J and Michiels S (2) |
Pocock, Stuart J | London School of Hygiene and Tropical Medicine, UK | 1995 | 5 | 67 | 54 | Boissel JP, Boutitie F, Fagard RH, Gueyffier F, Hamm CW, Hueb WA, King SB and Rodríguez A (2) |
Ray, Kausik K | St George’s University of London, UK | 2009 | 5 | 73 | 49 | Saltar N and Seshasai SRK (5) |
Rothwell, Peter M | University of Oxford, UK | 2003 | 5 | 36 | 19 | Belch JFF and Meade TW (3) |
Seshasai, Sreenivasa RK | University of Cambridge, UK | 2009 | 5 | 73 | 49 | Ray KK and SN (5) |
Simes, John | National Health and Medical Research Council Clinical Trials Centre, Australia | 2002 | 5 | 53 | 36 | Baigent C, Blackwell L, Collins R, Keech A and Peto R (3) |
Smith, George Davey | University of Bristol, UK | 1993 | 5 | 63 | 54 | Ebrahim S (4) |
Torgerson, David J | University of York, UK | 1999 | 5 | 46 | 39 | Adamson SJ and Bell Syer SEM (2) |
Wetterslev, Jorn | Copenhagen University Hospital, Denmark | 2007 | 5 | 28 | 15 | Gluud C (3) |
Wilt, Timothy J | Minneapolis VA Center for Chronic Disease Outcomes Research, USA | 1998 | 5 | 40 | 32 | MacDonald R (4) |
Institution, country | Total papers, n | Signatures, n | Institutional collaborations (with different institutions), n | Institutional collaborations in same country (domestic institutions), n | Institutional collaborations from different countries, n | Main institutional collaborator (number of papers) | Different collaborative countries, n |
---|---|---|---|---|---|---|---|
McMaster University, Canada | 49 | 216 | 109 | 31 | 78 | University of Toronto, Canada (10) | 19 |
University of Oxford, UK | 48 | 226 | 123 | 39 | 84 | Radcliffe Infirmary, UK (13) | 20 |
Harvard University, USA | 36 | 210 | 104 | 47 | 57 | Brigham and Women’s Hospital, USA (23) | 16 |
Brigham and Women’s Hospital, USA | 32 | 207 | 102 | 46 | 56 | Harvard University, USA (23) | 17 |
Radcliffe Infirmary, UK | 30 | 96 | 46 | 14 | 32 | University of Oxford, UK (13) | 11 |
University of London, UK | 29 | 207 | 125 | 34 | 91 | University of Bristol, UK; University of Edinburgh, UK and University of Oxford, UK (5) | 22 |
Copenhagen University Hospital, Denmark | 28 | 169 | 93 | 8 | 85 | Azienda Ospedaliera San Camillo-Forlanini, Italy; Université Paris V - René Descartes, France and University of Copenhagen, Denmark (4) | 20 |
University of Toronto, Canada | 27 | 123 | 55 | 23 | 32 | McMaster University, Canada and Sunnybrook Health Science Center, Canada (4) | 12 |
University of Sydney, Australia | 23 | 120 | 70 | 14 | 56 | National Health and Medical Research Council (NHMRC), Australia (6) | 15 |
University of Birmingham, UK | 22 | 80 | 51 | 26 | 25 | Queen Mary, University of London, UK and University of Aberdeen, UK | (3) 11 |
University of Bristol, UK | 22 | 141 | 96 | 33 | 63 | University of London, UK (5) | 21 |
University of Alberta, Canada | 20 | 94 | 57 | 14 | 43 | Institute of Health Economics, Canada and University of Calgary, Canada (4) | 15 |
University College London, UK | 19 | 123 | 88 | 33 | 55 | London School of Hygiene & Tropical Medicine, UK and Royal Free Hospital, UK (4) | 20 |
University Hospital Basel, Switzerland | 18 | 185 | 113 | 9 | 104 | Inselspital, Switzerland (5) | 20 |
Mayo Clinic, USA | 18 | 157 | 130 | 35 | 95 | University of Texas Medical School at Houston, USA (3) | 23 |
University of Glasgow, UK | 17 | 124 | 85 | 32 | 53 | University of Cambridge, UK (4) | 14 |
Erasmus MC University Medical Center Rotterdam, the Netherlands | 17 | 145 | 106 | 8 | 98 | Duke Clinical Research Institute (DCRI), USA and University of Sydney, Australia (3) | 23 |
Cleveland Clinic, UK | 16 | 75 | 51 | 11 | 40 | Duke Clinical Research Institute (DCRI), USA and University of Sydney, Australia (3) | 14 |
The University of York, UK | 16 | 64 | 44 | 26 | 18 | University of Leeds, UK (3) | 8 |
University of Bern, Switzerland | 16 | 128 | 72 | 8 | 64 | Inselspital, Switzerland (11) | 16 |
Medical Research Council’s Clinical Trials Unit, UK | 16 | 81 | 59 | 25 | 34 | University of Leicester, UK (3) | 14 |
Johns Hopkins University, USA | 15 | 58 | 42 | 18 | 24 | University Hospital Basel, Switzerland (2) | 11 |
Instituto di Ricerche Farmacologiche Mario Negri, Italy | 15 | 85 | 63 | 9 | 54 | University of Sydney, Australia (3) | 14 |
Hamilton Health Sciences, Canada | 14 | 64 | 37 | 5 | 32 | McMaster University, Canada (9) | 11 |
University of Calgary, Canada | 14 | 62 | 35 | 17 | 18 | University of Alberta, Canada (4) | 10 |
Tufts University, USA | 14 | 79 | 45 | 14 | 31 | Tufts Medical Center, USA (6) | 13 |
University of California, San Francisco, USA | 14 | 77 | 56 | 24 | 32 | San Francisco VA Medical Center, USA (3) | 16 |
University of Aberdeen, UK | 13 | 73 | 50 | 25 | 25 | NHS Grampian, UK (5) | 11 |
Sunnybrook Health Science Center, Canada | 13 | 83 | 45 | 17 | 28 | University of Toronto, Canada (10) | 9 |
University of Ottawa, Canada | 13 | 70 | 40 | 16 | 24 | Children’s Hospital of Eastern Ontario, Canada; McMaster University, Canada; Ottawa Hospital Research Institute (OHRI), Canada; University of Manitoba, Canada and University of Toronto, Canada (3) | 13 |
Wake Forest University, USA | 12 | 55 | 31 | 17 | 14 | University of East Anglia, UK and University of Washington, USA (4) | 7 |
Inselspital, Switzerland | 12 | 119 | 67 | 8 | 59 | University of Bern, Switzerland (11) | 16 |
University of Washington, USA | 12 | 44 | 25 | 12 | 13 | VA Puget Sound Health Care System, USA and Wake Forest University, USA (4) | 8 |
University of Edinburgh, UK | 12 | 106 | 66 | 30 | 36 | University of London, UK (5) | 17 |
Technical University of Munich, Germany | 11 | 110 | 63 | 3 | 60 | Columbia University Medical Center (CUMC), USA (4) | 17 |
Queen Mary, University of London, UK | 11 | 46 | 31 | 8 | 23 | University of Birmingham, UK (3) | 9 |
Tufts Medical Center, USA | 11 | 41 | 16 | 8 | 8 | Tufts University, USA (6) | 3 |
London School of Hygiene & Tropical Medicine, UK | 11 | 106 | 86 | 15 | 71 | University College London, UK (4) | 25 |
University of Pittsburgh, USA | 11 | 64 | 51 | 16 | 35 | Erasmus MC University Medical Center Rotterdam, the Netherlands and Ohio State University, USA (2) | 12 |
Country | Total papers, n | Papers per million inhabitants, n | Collaborations, n | Distinct countries of collaborations, n | Main collaborator(s) (number of collaborations) |
---|---|---|---|---|---|
USA | 310 | 0.99 | 428 | 43 | UK (63) |
UK | 297 | 4.73 | 380 | 44 | USA (69) |
Canada | 143 | 4.15 | 200 | 29 | USA (53) |
Australia | 70 | 3.14 | 165 | 30 | UK (30) |
Italy | 57 | 0.94 | 205 | 29 | USA (34) |
The Netherlands | 57 | 3.41 | 173 | 27 | USA (27) |
France | 51 | 0.78 | 159 | 27 | USA (26) |
Germany | 50 | 0.61 | 164 | 32 | USA (30) |
Switzerland | 47 | 5.94 | 177 | 35 | USA (25) |
Denmark | 41 | 7.36 | 124 | 28 | UK (18) |
Belgium | 23 | 2.09 | 92 | 23 | UK (14) |
Sweden | 21 | 2.22 | 69 | 14 | USA (13) |
Spain | 19 | 0.41 | 76 | 28 | USA (8) |
Norway | 14 | 2.83 | 56 | 20 | UK and USA (11) |
Japan | 13 | 0.10 | 51 | 21 | USA (9) |
New Zealand | 13 | 2.95 | 24 | 11 | UK (8) |
Finlad | 11 | 2.04 | 43 | 14 | Australia and USA (7) |
Brazil | 9 | 0.05 | 40 | 16 | UK and USA (5) |
Greece | 8 | 0.71 | 12 | 5 | UK and USA (4) |
Israel | 8 | 1.03 | 7 | 5 | USA (3) |
Ireland | 6 | 1.31 | 24 | 14 | UK (5) |
China | 6 | 0.00 | 10 | 7 | USA (4) |
South Africa | 6 | 0.12 | 23 | 16 | USA (4) |
Argentina | 5 | 0.12 | 24 | 13 | Brazil, Switzerland, UK and USA (3) |
Czech Republic | 5 | 0.48 | 42 | 18 | UK and USA (5) |
Poland | 5 | 0.13 | 23 | 13 | UK (4) |
South Korea | 5 | 0.10 | 31 | 13 | USA (4) |
Austria | 4 | 0.47 | 9 | 6 | Germany (3) |
Thailand | 4 | 0.06 | 10 | 10 | All countries (1) |
Chile | 3 | 0.17 | 10 | 8 | Canada and USA (2) |
India | 3 | 0.00 | 2 | 2 | Australia and UK (1) |
Portugal | 3 | 0.28 | 1 | 1 | Canada (1) |
Taiwan | 3 | 0.13 | 3 | 3 | Denmark, UK and USA (1) |
Costa Rica | 2 | 0.42 | 8 | 6 | Canada and USA (2) |
Hungary | 2 | 0.20 | 16 | 14 | UK and USA (2) |
Pakistan | 2 | 0.01 | 2 | 1 | UK (2) |
Russia | 2 | 0.01 | 18 | 14 | Belgium, Denmark, Germany, and UK (2) |
Saudi Arabia | 2 | 0.07 | 7 | 6 | UK (2) |
Serbia and Montenegro | 2 | 0.28 | 4 | 2 | Denmark and Italy (2) |
Turkey | 2 | 0.03 | 13 | 9 | Australia, Canada, Switzerland and USA (2) |
Colombia | 1 | 0.02 | 6 | 6 | All countries (1) |
Cuba | 1 | 0.09 | 5 | 5 | All countries (1) |
Gabon | 1 | 0.65 | 10 | 10 | All countries (1) |
Ghana | 1 | 0.04 | 10 | 10 | All countries (1) |
Latvia | 1 | 0.49 | 12 | 12 | All countries (1) |
Mexico | 1 | 0.01 | 1 | 1 | USA (1) |
Morocco | 1 | 0.03 | 10 | 10 | All countries (1) |
Mozambique | 1 | 0.04 | 10 | 10 | All countries (1) |
Republic of Malawi | 1 | 0.07 | 1 | 1 | UK (1) |
Singapore | 1 | 0.19 | 0 | 0 | - |
Tanzania | 1 | 0.02 | 10 | 10 | All countries (1) |