Bias (Epidemiology), Clinical trials, Consensus, Endpoint determination/standards, Evidence-based medicine, Guidelines, Research design/standards, Systematic reviews, Treatment outcome



  1. Section Editor(s): Khan, Khalid

Article Content

Clinical trials, systematic reviews, and guidelines compare beneficial and nonbeneficial outcomes following interventions. Often, however, various studies on a particular topic do not address the same outcomes, making it difficult to draw clinically useful conclusions when a group of studies is looked at as a whole (Williamson et al., 2012). This problem was recently thrown into sharp focus by a systematic review of interventions for preterm birth prevention, which found that among 103 randomized trials, no fewer than 72 different outcomes were reported (Meher & Alfirevic, 2014). There is a growing recognition among clinical researchers that this variability undermines consistent synthesis of the evidence, and that what is needed is an agreed standardized collection of outcomes-a "core outcomes set"-for all trials in a specific clinical area (Williamson et al., 2012). Recognizing that the current inconsistency is a serious hindrance to progress in our specialty, the editors of over 50 journals related to women's health have come together to support The CROWN (CoRe Outcomes in WomeN's health) Initiative (Box 1).

Box 1 - Click to enlarge in new windowBox 1. Aims of The CROWN Initiative

Development of consensus is required around a set of well-defined, relevant, and feasible outcomes for all trials concerning particular obstetric and gynecologic health conditions, such as preterm birth, incontinence, infertility, and menstrual problems. With so many subspecialties involved, this is no easy task. Duplication of effort can be avoided by working with the Core Outcome Measures in Effectiveness Trials (COMET) Initiative, which is working toward core data sets for all medical specialties (Williamson, Altman, Blazeby, Clarke, & Gargon, 2011). Production of trustworthy core outcome sets will require engagement with patients, healthcare professionals, researchers, industry and regulators, and the employment of scientifically robust consensus methods (Williamson et al., 2012). The data for these core outcome sets, once agreed upon, should be collected in trials and reported in publications as standard practice in the future.


Journal editors now invite researchers to take the lead in beginning this work. What will we do as editors to support them and their colleagues? First, we are drawing wide attention to The CROWN Initiative by publishing this editorial in the journals listed below. We shall ensure that the global research community, which includes our many reviewers, is aware of the need for core outcome sets. Submissions that describe development of core outcome sets, if deemed acceptable after peer review, will be effectively disseminated.


Our collaboration is not for enforcing harmony at the expense of innovation. To quote from the COMET home page ( "The existence or use of a core outcome set does not imply that outcomes in a particular trial should be restricted to those in the relevant core outcome set. Rather, there is an expectation that the core outcomes will be collected and reported, making it easier for the results of trials to be compared, contrasted and combined as appropriate; while researchers continue to explore other outcomes as well." We also expect that as new or superior ways of capturing outcomes emerge, core outcome sets will themselves need updating.


Producing, disseminating, and implementing core outcome sets will ensure that critical and important outcomes with good measurement properties are incorporated and reported. We believe this is the next important step in advancing the usefulness of research, in informing readers, including guideline and policy developers, who are involved in decision-making, and in improving evidence-based practice.


The CROWN Initiative is grateful to James Duffy (Trainee Scientific Editor, BJOG) and Louisa Waite (Assistant Editor, BJOG) for the drafting, revision, and coordination required for the preparation of this article.


The author declares no conflict of interest.


Note: Reproduced from The Core Outcomes in Women's Health (CROWN) Initiative with permission from the Royal College of Obstetricians and Gynaecologists and John Wiley & Sons Ltd.


The CROWN Initiative includes the following journals, in alphabetical order (correct on 13th May 2014, up to date list available at


1. Acta Obstetricia et Gynecologica Scandinavica


2. American Journal of Obstetrics & Gynecology


3. American Journal of Perinatology


4. Archives of Gynecology and Obstetrics


5. Australian and New Zealand Journal of Obstetrics and Gynaecology


6. Best Practice & Research: Clinical Obstetrics & Gynaecology


7. Birth: Issues in Perinatal Care


8. BJOG: An International Journal of Obstetrics and Gynaecology


9. BMC Pregnancy and Childbirth


10. BMC Women's Health


11. Climacteric


12. Clinical Obstetrics and Gynecology


13. Clinics in Perinatology


14. Cochrane Menstrual Disorders and Subfertility Group


15. Cochrane Pregnancy and Childbirth Group


16. Contraception


17. Current Opinion in Obstetrics and Gynecology


18. European Journal of Obstetrics & Gynecology and Reproductive Biology


19. Fertility and Sterility


20. Fetal Diagnosis and Therapy


21. Ginekologia Polska


22. Gynecological Surgery


23. Gynecologic Oncology


24. Gynecologic Oncology Reports


25. Human Fertility


26. Human Reproduction


27. Human Reproduction Update


28. Hypertension in Pregnancy


29. International Journal of Fertility and Sterility


30. International Breastfeeding Journal


31. International Journal of Gynecology & Obstetrics


32. International Urogynecology Journal


33. Journal of Family Planning and Reproductive Health Care


34. Journal of Gynecologic Oncology


35. Journal of Lower Genital Tract Disease


36. Journal of Midwifery & Women's Health


37. Journal of Obstetrics & Gynaecology


38. Journal of Obstetrics and Gynaecology Canada


39. Journal of Obstetric, Gynecologic & Neonatal Nursing


40. Journal of Perinatal & Neonatal Nursing


41. Journal of Perinatal Medicine


42. Maturitas


43. MCN The American Journal of Maternal Child Nursing


44. Menopause Review (Przegl a d Menopauzalny)


45. Menopause: The Journal of The North American Menopause Society


46. Neurourology and Urodynamics


47. Obstetrics & Gynecology


48. Paediatric and Perinatal Epidemiology


49. Placenta


50. Prenatal Diagnosis


51. Reproductive Health


52. The Breast Journal


53. The European Journal of Contraception and Reproductive Health Care


54. The Obstetrician & Gynaecologist (TOG)


55. Twin Research and Human Genetics


56. Ultrasound in Obstetrics & Gynecology





Meher S., Alfirevic Z. (2014). Choice of primary outcomes in randomised trials and systematic reviews evaluating interventions for preterm birth prevention: A systematic review. BJOG: An International Journal of Obstetrics and Gynaecology. doi:10.1111/1471-0528. [Context Link]


Williamson P. R., Altman D. G., Blazeby J. M., Clarke M., Devane D., Gargon E., Tugwell P. (2012). Developing core outcome sets for clinical trials: Issues to consider. Trials, 13, 132. doi:10.1186/1745-6215-13-132 [Context Link]


Williamson P. R., Altman D. G., Blazeby J. M., Clarke M., Gargon E. (2011). The COMET (Core Outcome Measures in Effectiveness Trials) Initiative. Trials, 12(Suppl. 1), A70. doi:10.1186/1745-6215-12-S1-A70 [Context Link]