Intended for healthcare professionals

Rapid response to:


Trial registration 10 years on

BMJ 2015; 351 doi: (Published 06 July 2015) Cite this as: BMJ 2015;351:h3572

Rapid Response:

Study registration 10 years forward: a perspective on observational research

Dear Sir,

We read with interest the editorial by Weber and colleagues [1]. Clinical trial registration provides centralisation of methodological quality assurance to all healthcare stakeholders. The pre-publication of trial protocols minimises post-hoc statistical manipulation and subsequent reporting bias. Interventional study registration has now therefore become a requirement for publication in most prominent scientific journals [2]. Across other study types, pre-registration of study protocols is also emerging as standard of practice. For example, a recent British Medical Journal (BMJ) publication outlined the 17-item ‘PRISMA-P’ checklist for protocol-driven systematic review and meta-analysis [3]. However, the mandate for pre-publication of a study protocol is yet to descend upon observational study types.

Observational studies represent 90% of published research, influencing clinical decision-making where published clinical trial data is lacking [4]. The STrengthening the Reporting of OBservational studies in Epidemiology group (STROBE, have identified protocol registration as one of the key steps in improving quality of observational studies and reducing the selective reporting bias [5]. It has been suggested that a priori definition of a primary endpoint and statistical analysis strategy would significantly improve the quality of evidence generated from these studies, with impact on grouped analyses [6, 7]. Whilst it is possible to publish protocols for observational research on registries such as, this is infrequent, with only 17% of studies registered here being of observational design [8].

Some journals have pioneered mandatory protocol registration for observational studies (e.g. the Lancet). However many, including the BMJ are yet to follow suit (e.g. The Journal of the American Medical Association, Annals of Surgery and the British Journal of Surgery). We encourage authors to preregister study protocols for observational research, and for journal editors to require this. This is particularly important in surgery, where observational studies predominate, and risk of bias is high [6].

John Manley, James Lloyd, James C Glasbey*

University Hospital of Wales, Cardiff, UK

Acknowledgments: With thanks to the Cardiff University Research Society (CuRES) - Short Duration Project Scheme (

[1] Weber WE, Merino JG, Loder E. Trial registration 10 years on. BMJ. 2015 Jul 6;351:h3572. doi: 10.1136/bmj.h3572.

[2] Zarin DA, Tse T. Medicine. Moving toward transparency of clinical trials. Science. 2008;319(5868):1340-2.

[3] Shamseer L, Moher D, Clarke M, Ghersi D, Liberati A, Petticrew M, et al. Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation. BMJ. 2015;349:g7647.

[4] Boccia S. Credibility of observational studies: why public health researchers should care? Eur J Public Health. 2015.

[5] Peat G, Riley RD, Croft P, Morley KI, Kyzas PA, Moons KG, et al. Improving the transparency of prognosis research: the role of reporting, data sharing, registration, and protocols. PLoS Med. 2014;11(7):e1001671.

[6] The PLOS Medicine Editors (2014) Observational Studies: Getting Clear about Transparency. PLoS Med 11(8): e1001711.

[7] Wu R, Glen P, Ramsay T, Martel G. Reporting quality of statistical methods in surgical observational studies: protocol for systematic review. Syst Rev. 2014;3:70.

[8] Williams RJ, Tse T, Harlan WR, Zarin DA. Registration of observational studies: is it time? CMAJ. 2010;182(15):1638-42.

Competing interests: No competing interests

20 July 2015
James C Glasbey
Academic Foundation Doctor
John Manley, James Lloyd
School of Postgraduate Medical Education
University Hospital of Wales, Heath Park, Cardiff, UK