Table 1 Characteristics of included studies (N=15)
Study | Study aim | Study design | Material | Country | Inclusion period | Area of interests | Results | Conclusion |
|---|---|---|---|---|---|---|---|---|
Clarke M, Alderson P, Chalmers I. (2002) [27] | To assess whether RCTs in 5 general medical journals discuss new results in light of available evidence. | Cross-sectional | RCTs published in Annals of Int Med, BMJ, JAMA, Lancet and NEJM | UK | May 2001 | No specific speciality | 33 RCTs included. 0 (0%) updated a SR. 3 (9%) cited SR | Little evidence exists to suggest the results of an RCT are discussed in light of the totality of the available evidence. |
Clarke M, Chalmers I. (1998) [18] | To assess whether RCTs in 5 general medical journals discuss new results in light of available evidence. | Cross-sectional | RCTs published in Annals of Int Med, BMJ, JAMA, Lancet and NEJM | UK | May 1997 | No specific speciality | 26 RCTs included. 0 (0%) updated a SR. 6 (23%) cited SR | Little evidence exists to suggest journals have adequately implemented the CONSORT recommendation that results of an RCT be discussed in light of the totality of the available evidence. |
Clarke M, Hopewell S. (2013) [30] | To assess whether RCTs in 5 general medical journals discuss new results in light of available evidence. | Cross-sectional | RCTs published in Annals of Int Med, BMJ, JAMA, Lancet and NEJM | UK | May 2012 | No specific speciality | 35 RCTs included. 2 (6%) updated an SR. 11 (31%) cited SR | Many trials still do not use SRs in their reporting. |
Clarke M, Hopewell S, Chalmers I. (2007) [28] | To assess whether RCTs in 5 general medical journals discuss new results in light of available evidence. | Cross-sectional | RCTs published in Annals of Int Med, BMJ, JAMA, Lancet and NEJM | UK | May 2005 | No specific speciality | 18 RCTs included. 0 (0%) updated a SR. 5 (28%) cited SR | Little evidence suggests results of an RCT are discussed in light of the totality of the available evidence. Although the proportion of trials referring to SRs in ‘Discussion’ sections has increased, the majority of reports continued to fail even to do this. |
Clarke M, Hopewell S, Chalmers I. (2010) [29] | To assess whether RCTs in 5 general medical journals discuss new results in light of available evidence. | Cross-sectional | RCTs published in Annals of Int Med, BMJ, JAMA, Lancet and NEJM | UK | May 2009 | No specific speciality | 29 RCTs included. 1 (4%) updated an SR. 10 (35%) cited SR | Little evidence exists to suggest results of an RCT are discussed in light of the totality of the available evidence. Although the proportion of trials referring to SRs has increased, most reports still fail to do this. |
Engelking A, Cavar M, Puljak L. (2018) [26] | To analyse whether existing SRs were mentioned in RCTs published as a rationale for discussing the results. | Cross-sectional and meta-analysis | RCTs published in Anaesthesia, Anaesthesia and Analgesia, Anaesthesiology, Pain, British Journal of Anaesthesia, European Journal of Anaesthesiology, Regional Anaesthesia and Pain Medicine | Croatia | 2014–2016 | Anaesthesia, anaesthesia and analgesia, anaesthesiology, pain, | 622 RCTs included. 245 (39%) cited SR | No conclusion regarding placing new results in contexts of earlier results in the discussion section |
Goudie AC et al. (2010) [31] | To assess the extent to which authors currently make use of previous trial evidence in the reporting of RCTs. | Cross-sectional | RCTs published in JAMA and Archives of Internal Medicine | UK | January–May 2007 | No specific speciality | 27 RCTs included. 1 (4%) updated an SR. 10 (37%) cited SR | No conclusion regarding placing new results in contexts of earlier results in the discussion section |
Helfer B et al. (2015) [32] | To assess whether recent meta-analyses cite, describe, and discuss previous meta-analyses and SRs. | Cross-sectional | Meta-analyses published in NEJM, Lancet, JAMA, Annals of Int Med, PLOS Medicine, BMJ (pharmacological treatment) | Germany | January 2012–March 2013 | Pharmacological treatment | 52 meta-analyses included. 25 (48%) cite SR | Meta-analyses on pharmacological treatments do not consistently discuss the findings of previous meta-analyses on the same topic. |
Hoderlein X, Moseley AM, Elkins MR. (2017) [20] | To investigate the extent to which RCTs use high-quality clinical research to interpret the trial’s results and to assess a possible progress between 2001 and 2015. | Cross-sectional | Clinical trials randomly selected from Physiotherapy Evidence Database | Germany | 2001 and 2015 | Physiotherapy | 2001: 70 RCTs included. 0 (0%) updated a SR. 12 (17%) cited SR. 2015: 151 RCTs included. 1 (1%) updated an SR. 52 (34%) cited SR | Citing is increasing from 2001 to 2015, but integration with existing research in the ‘Discussion’ section is rare. |
Johnson AL, Walters C, Gray, H et al. (2020) [21] | To evaluate the use of SRs to justify RCTs…. And analyse the reference of SRs for trial justification in RCTs. | Cross-sectional | RCTs published in 3 high-ranking orthopaedic journals, and for comparison RCTs published in general orthopaedic journals | USA | January 1, 2015, to November 30, 2018 | Orthopaedia | 128 RCTs included. No data on SRs in the ‘Discussion’ section | SRs are frequently cited in orthopaedic trauma RCTs but are not commonly cited as justification for conducting a clinical trial. |
Rauh S, Nigro T, Sims M et al. (2020) [22] | To analyse published articles for citation of SRs for justification of conducting RCTs. | Cross-sectional | RCTs in obstetrics and gynaecology journals | USA | January 1, 2014–December 31, 2017 | Obstetrics and gynaecology | 458 trials were included. 207 (45.2%) cited SRs | A large portion of the RCTs recently published in clinical obstetrics and gynaecology journals are not citing SRs as justification for conducting their studies, which may be leading to an increase in research waste. |
Rosenthal R, Bucher HC, Dwan K. (2017) [23] | The aim was to investigate to what extent information from SRs is used to synthesise results. | Cross-sectional | RCTs published in Annals of Surgery, JAMA Surgery, British Journal of Surgery | Switzerland | 2010 | Surgery | 51 RCTs included. 0 (0%) updated an SR. 9 (18%) cited SR | SRs are considered for summarising findings […] rather than for knowledge synthesis after trial conduct. |
Shephard S, Wise A, Johnson BS et al. (2021) [19] | To appraise the use of SRs as justification in RCTs …and report the manner in which SRs were incorporated into RCT manuscripts published in those journals. | Cross-sectional | RCTs published in the top four urology journals based on Google Scholar h5 index | USA | November 30, 2014–November 30, 2019 | Urology | 276 RCTs included. No data on SRs in the ‘Discussion’ section | RCTs published in four high-impact urology journals inconsistently referenced an SR as justification, and 39.1% of our entire sample did not reference an SR at all. |
Torgeson T, Evans S, Johnson BS et al. (2020) [25] | To evaluate the use of SRs to justify conducting RCTs in top ophthalmology and optometry journals. | Cross-sectional | RCTs published in the top five Google Scholar h-5 index journals Ophthalmology and Optometry | USA | December 5, 2018 | Ophthalmology and optometry | 152 RCTs included. 35 (23%) cited SR | Less than one quarter of phase III RCTs cited SRs as justification for conducting the RCT. |
Walters C, Torgeson T, Fladie I et al. (2020) [24] | To evaluate whether RCTs … referenced SRs as the basis for conducting a trial. | Cross-sectional | RCTs published in three high-impact factor general medicine journals (NEJM, Lancet, JAMA) | USA | January 1, 2016–August 31, 2018 | General medicine | 637 RCTs included. No data on SRs in the “Discussion” section | Less than half of the analysed clinical trials cited SRs as the basis for undertaking the trial. |