First author, publication year, journal | Study area | Data sources for protocols /registrations | Data sources for full reports | Study search frameb | Numbers of protocols (or registrations)/full reports | Study design of primary studies | Measures of comparison between protocols /registrations and full reports | Study country of primary studies | Study sample size of full reports in primary studies | Funding for the systematic review or survey |
---|---|---|---|---|---|---|---|---|---|---|
Survey (n = 33) | ||||||||||
Al-Marzouki, 2008, The Lancet [17] | Composite areas | Protocols published on The Lancet’s website | Contacting investigators and database searching | Protocols: As of June, 2007 | 64/37 | RCTs | Selective outcome reporting and subgroup analyses | Not reported | Not reported | Not reported |
Chan, 2004, Canadian Medical Association or its licensors [19] | Composite areas | Protocols approved by Canadian Institutes of Health Research (CIHR) or Medical Research Council of Canada (MRC) | PubMed, EMBASE and the Cochrane Controlled Trials Register | Protocols: 1990–1998; Full reports: up to 2003 | 48/68 | RCTs | Outcome reporting | Canada | Median sample size: 299 | Not reported |
Chan, 2004, Journal of the American Medical Association [7] | Composite areas | Protocols approved by Scientific-Ethical Committees for Copenhagen and Frederiksberg’ Denmark | Contacting trialists and by searching MEDLINE, EMBASE, and the Cochrane Controlled Trials Register | Protocols: 1994–1995; Full reports: up to May 2003 | 102/122 | RCTS | Outcome reporting | Denmark | Median sample size: 151 for parallel RCTs; 16 for crossover RCTs | Academic funding |
Chan, 2008, British Medical Journal [8] | Composite areas | Protocols approved by Scientific-Ethical Committees for Copenhagen and Frederiksberg, Denmark | PubMed, Embase, and the Cochrane Controlled Trials Register | Protocols: from January 1994 to December 1995 | 70/70 | RCTs | Sample size calculations and data analyses | Denmark | Median sample size: 66 for per study arm | No funding received |
Hartung, 2014, Annals of Internal Medicine [22] | Composite area | ClinicalTrials.gov | PubMed or the National Library of Medicine | Protocols: if trials completed before January 2009, or trials starting before July 2008 if primary completion date was unknown | 110/110 | RCTs | Outcome reporting, study sample and results presentations | Not reported | Median sample size: 352 | Academic funding |
Kasenda, 2014, British Medical Journal [9] | Composite areas | Protocols approved by six research ethics committees in Switzerland (Basel, Lucerne, Zurich, and Lausanne), Germany (Freiburg), and Canada (Hamilton) | Publications of trials from corresponding protocols | Protocols: approved between 2000 and 2003 | 894/515 | RCTs | Subgroup analyses | Switzerland, Germany, and Canada. | Median sample size: 260 | Academic funding |
Redmond, 2013, Journal of Clinical Epidemiology [34] | Composite areas | Protocols submitted to Research Ethics Committee of the University Hospital Bern (Inselspital), Switzerland | CENTRAL database (Cochrane Library) | Protocols: from 1988 to 1998; Full reports: from 1990 to 2008 | 227/333 | RCTs | Outcome reporting | Switzerland | Median sample size 330 | Academic funding |
Hahn, 2002, Journal of Evaluation in Clinical Practice [20] | Composite areas | Protocols from a local research ethics committee | Contacted the lead researcher | Not reported | 37/15 | Clinical trials | Selective reporting including study samples, outcomes, statistical plans, and result interpretations | Not reported | Not reported | Not reported |
Dekkers, 2015, Journal of Clinical Epidemiology [11] | Composite areas | Protocols submitted to three research ethics committees in Switzerland and The Netherlandsa | MEDLINE via PubMed, the Cochrane Controlled Trials Register and Google Scholar | Protocols: 2001 to 2005. Full reports: up to September 2012 | 54/54 | Non-inferiority RCTs | Noninferiority margins | Switzerland and The Netherlands | Not reported | Academic funding |
Clinical Trials Registry Platform of the World Health Organization | MEDLINE via PubMed, the Cochrane Controlled Trials Register and Google Scholar | Registrations: up to March 2013. Full reports: up to September 2012 | 29/54 | |||||||
Saquib, 2013, British Medical Journal [41] | Composite areas | Registration entries, protocols obtained by personal communication, and by searching design papers | Publications in PubMed in 25 biomedical journals with the highest impact factor | Full reports: publications published in 2009 | 162/199 | RCTs | Statistical adjustments for primary outcomes | Not reported | Not reported | No funding received |
Riveros, 2013, Plos Medicine [37] | Composite areas | Clinicaltrials.gov | Medline via PubMed | Registrations: up to March 2012. Full reports: up to March 2012 | 600/202 | RCTs | Selective and incomplete outcome reporting | Not reported | Not reported | Academic funding |
Boonacker, 2011, American Journal of Epidemiology [18] | Composite areas | Grant applications awarded by the Health Care Efficiency Research Program of the Netherlands Organization for Health Research and Development (ZonMw) | Pubmed | Grant applications: from 2001 to March 2010; Full reports: up to June 2010 | 79/79 | RCTs and observational studies | Subgroup analyses | The Netherlands | Not reported | No funding received |
Rising, 2008, PLOS Medicine [36] | Composite areas | FDA (Food and Drug Administration) reviews of approved NDAs (New Drug Applications) for new molecular entities (NMEs) | PubMed and The Cochrane Library | FDA reviews: from January 2001 to December 2002. Full reports: from July 2006 through June 2007 | 128/164 | Clinical trails | Outcome reporting, statistical plan and conclusion | Not reported | Median sample size: 392 | Academic funding |
Hannink, 2013, Annals of Surgery [21] | Surgery | ClinicalTrials.gov, the International Standard Randomised Controlled Trial Number Registry (ISRCTN), Australian New Zealand Clinical Trials Registry (ANZCTR), or otherregistry | PubMed in 10 general medical journals and 10 surgical journals with the highest impact factors | Registrations: between 2007 and 2012. Full reports: between 2007 and 2012 | 152/152 | RCTs | Outcome reporting | Not reported | Not reported | Not reported |
Killeen, 2014, Annals of Surgery [24] | Surgery | Clinical trials.gov, ISRCTN, WHO trial registry portal, and the national/regional trial registry of the country of origin of the trial, and by e-mailing the corresponding author | The 10 surgical journals with the highest impact factor for 2009 | Registrations: from 2009 to 2010. Full reports: from 2009 to 2010 | 108/108 | RCTs | Outcome reporting | Not reported | Not reported | Not reported |
Rongen, 2016, The Journal of Bone and Joint Surgery [38] | Orthopaedics | From the published articles, and by manually searching the corresponding trial registry and/or corresponding number | PubMed in the ten orthopaedic journals with the highest impact factors | Registrations: from January 2010 through December 2014. Full reports: from January 2010 through December 2014 | 26/26 | RCTs | Primary outcome reporting | Not reported | Not reported | No funding received |
Rosenthal, 2013, Annals of Surgery [40] | Surgery | Clinicaltrials.gov, the ISRCTN registry, and the WHO International Clinical Trials Registry Platform | The Annals of Surgery, Archives of Surgery, and British Journal of Surgery | Registrations and full reports: from January 2010, and December 2010 | 51/51 | RCTs | Study sample, intervention, outcome reporting, statistical plan, study design, time duration, and funding/sponsor/ethics approval | Not reported | Not reported | No funding received |
Vedula, 2009, The New England Journal of Medicine [45] | Pharmacotherapeutic studies (for gabapentin) | Internal company documents from Parke-Davis and Pfizer | Publications for trials sponsored by Parke-Davis and Pfizer | Protocols: partly from internal company documents, up to 2008. Full reports: up to 2008 | 20/12 | Clinical trials | Outcome reporting | Not reported | Not reported | Litigation-related consultant fees |
Vedula, 2013, PLOS Medicine [10] | Pharmaco therapeutic studies (for gabapentin) | Internal company documents from Parke-Davis and Pfizer | Publications for trials sponsored by Parke-Davis and Pfizer | Protocols: partly from internal company documents, up to 2008. Full reports: up to 2008 | 21/11 | Clinical trials | Analysis reporting | Not reported | Not reported | Litigation-related consultant fees |
Norris, 2014, Res. Syn. Meth [33] | Pharmacotherapeutic studies | International Clinical Trials Registry Platform | Publications of trials included in three comparative effectiveness reviews | Registrations: from January 2005 to January 2012. Full reports: from January 2005 to January 2012 | 50/50 | RCTs | Selective outcome reporting and selective analysis reporting | Not reported | Not reported | Academic funding |
Melander, 2003, British Medical Journal [29] | Pharmaco therapeutic study (for selective serotonin reuptake inhibitors) | For short term (4–8 weeks) RCTs with approved doses, applications that were submitted to the Swedish drug regulatory authority for marketing authorization and that included all relevant information | Medline (PubMed), Embase, and PsycINFO (Psychological Abstracts) | Applications: between 1983 and 1999. Full reports: between 1983 and 1999 | 42/38 | Clinical trials | Analysis reporting | Sweden | Not reported | No funding received |
Soares, 2004, British Medical Journal [48] | Oncology | Protocols for terminated RCTs conducted by Radiation Therapy Oncology Group | Publications of terminated RCTs conducted by Radiation Therapy Oncology Group | Protocols and full reports: from 1968 onward | 56/58 | RCTs | Study design, statistical plan, result presentation | USA and Canada | Not reported | Academic funding |
Vera-Badillo, 2013, Annals of Oncology [46] | Oncology (for breast cancer) | ClinicalTrials.gov | PubMed | Registrations and full reports: from January 1995 to August 2011 | 30/164 | RCTs | Outcome reporting | Not reported | Not reported | Not reported |
Korevaar, 2014, Clinical Chemistry [25] | Diagnostic testing | ClinicalTrials.gov | PubMed, EMBASE, and Web of Science and by contacting investigators | Protocols: between January 2006 and December 2010. Full reports: up to 2013 | 418/153 | Clinical trials | Inclusion criteria, results presentations and outcome reporting | Most in USA and Europe | Median sample size: 172 | Not reported |
Li, 2013, Scandinavian Journal of Gastroenterology [26] | Gastroenterology and hepatology | From the published article, and by searching the articles in the registries | PubMed search in top five general and internal journals and top five gastroenterology and hepatology journals | Registrations: from January 2009 to December 2012. Full reports: from January 2009 to December 2012 | 252/305 | RCTs | Primary outcome reporting | 46% in Europe | Median sample size: 388 in general and internal journals; 107 in gastroenterology and hepatology journals | No funding received |
Mathieu, 2009, Journal of the American Medical Association [27] | Cardiology, rheumatology, and gastroenterology | From the published article, or corresponding author, or by searchingClinicalTrials.gov, ISRCTN registry, the registry of the country of the first or corresponding author, and World Health Organization (WHO) registry search portal | MEDLINE via PubMed and the 10 general medical journals and specialty journals with the highest impact factors | Registrations: up to March 2009. Full reports: up to March 2009 | 147/323 | RCTs | Primary outcome reporting | Not reported | Not reported | Academic funding |
Maund, 2014, British Medical Journal [28] | Major depressive disorder | Applications (including protocols and clinical study reports) submitted to European Medicines Agency (EMA) for study approvaland evaluation; registrations from Clinicaltrials.gov | PubMed and Cochrane Central Register of Controlled Trials, and by contacting the manufacturer | Applications and registrations: up to March 2013. Full reports: up to March 2013 | 9/7 | RCTs | Results presentations and interpretations | Not reported | 2878 in total | Academic funding |
Milette, 2011, Journal of Psychosomatic Research [31] | Psychosomatic and behavioral health | From the published article, or corresponding author, or by searchingClinicalTrials.gov, ISRCTN registry, the registry of the country of the first or corresponding author. and World Health Organization registry search portal | Publications in PubMed in Annals of Behavioral Medicine, Health Psychology, Journal of Psychosomatic Research, and Psychosomatic Medicine | Registrations: from January 2008 to September 2009. Full reports: from January 2008 to September 2009 | 13/63 | RCTs | Outcome reporting | Not reported | Nor reported | Nor reported |
Nankervis, 2012, Journal of Investigative Dermatology [32] | Dermatology | WHO International Clinical Trial Registry Platform | Global Resource of Eczema Trials (GREAT) database | Registrations: from January 2007 to July 2011. Full reports: from January 2007 to July 2011 | 37/109 | RCTs | Outcome reporting | Not reported | Median sample size: 70 for registered trials, 60 for unregistered trials | Academic funding |
Riehm, 2015, Journal of Psychosomatic Research [35] | Psychosomatic and behavioral health | From the published article, or corresponding author, or by searchingClinicalTrials.gov, ISRCTN registry, the registry of the country of the first or corresponding author. and World Health Organization registry search portal | Publications in PubMed in Annals of Behavioral Medicine, Health Psychology, Journal of Psychosomatic Research, and Psychosomatic Medicine | Registrations: from January 2013 to October 2014. Full reports: from January 2013 to October 2014 | 40/76 | RCTs | Outcome reporting | Not reported | Not reported | No funding |
Rosati, 2016, Trials [39] | Pediatrics | Clinical trial registries including the United States National Institute of Health (clinicaltrials.gov), the ISRCTN registry, the Nederlands Trials Register (NTR), the Australian and New Zealand Clinical Trial Registry (ACTRN), and the Clinical Trial Registry-India (CTRI) | 20 consecutive RCTs published from July to November 2013 in the journal Pediatrics | Registrations: from July 2013 to November 2013. Full reports: from July 2013 to November 2013 | 20/20 | RCTs | Outcome reporting, sample size, statistical plan, result interpretation | Most conducted in USA | Not reported | No funding received |
Su, 2015, Trials [43] | Acupuncture | 15 major international trial registries | PubMed and three Chinese databases | Registrations and full reports: up to January 2014 | 88/96 | RCT | Outcome reporting, inclusion criteria, and comparator | Most conducted in western countries (74%) | Sample size ranged from 10 to 960 | Not reported |
Turner, 2012, PLoS Medicine [44] | Antipsychotic Trials | FDA reviews on eight second-generation antipsychotic drugs for the treatment of schizophrenia | PubMed and Cochrane Central Register of Controlled Trials | FDA reviews: from December 1993 to May 2005. Full reports: up to May 2010 | 24/20 | Clinical trials | Outcome reporting, result presentation | Not reported | Not reported | Academic funding |
Systematic review (n = 4) | ||||||||||
Mhaskar, 2012, Journal of Clinical Epidemiology [30] | Oncology | Protocols of trials conducted by eight National Cancer Institute Cooperative Groups | Publications of trials conducted by eight National Cancer Institute Cooperative Groups | Protocols and full reports: Up to 2006 | 429/429 | RCTs (Phase III) | Study sample, comparator, outcome, study design, statistical plan and randomization | Not reported | Not reported | Academic funding |
You, 2012, Journal of clinical oncology [47] | Oncology | ClinicalTrials.gov and ISRCTN registry | MEDLINE via PubMed in 10 journals | Registrations: from August 2009 to April 2010. Full reports: from January 2005 to December 2009 | 215/366 | RCTs | Outcome reporting | Not reported | Not reported | Academic funding |
Hernandez, 2005, Neurosurgery [23] | Surgery (for traumatic brain injury) | Not reported | MEDLINE, EMBASE, the Cochrane Controlled Trials Register and the Cochrane Database of Systematic Reviews for RCTs | Full reports: up to April 2004 | 6/6 | RCTs | Subgroup analyses | Most in USA and Europe | Median sample size: 463 | Not reported |
Smith, 2013, Pain [42] | Analgesic studies | ClinicalTrials.gov | Registered Analgesic Clinical Trials (RReACT) database | Full reports: Trials registered at ClinicalTrials.gov as of December 2011 | 87/87 | Clinical Trials | Outcome reporting | Not reported | Median sample size: 167 | Not reported |