UCL Antimicrobial Resistance


ORION Statement: A CONSORT equivalent for infection control intervention studies & outbreak reports

The ORION statement is a reporting guideline for infection control intervention studies and outbreak reports of health care associated infection (HCAI). Just as the CONSORT statement sets standards for reporting randomised controlled trials, ORION sets standards addressing the wide variety of interventions, settings, designs, and statistical issues relating to HCAI and evaluations of interventions to change hospital antibiotic prescribing. It is particularly suitable for non-randomised studies, especially interrupted time series, with and without controls, and outbreak reports, and can be applied to most infection control intervention studies whether the primary outcome is reduced infection levels or better clinical practice. Many aspects however, such as detailed description of interventions, potential confounders and correct choice of statistical analyses also apply to randomised studies in this area. 

ORION arose from collaboration between the Health Technology Assessment (HTA) systematic review of isolation practices for MRSA, based at UCL, and the Cochrane review of antibiotic stewardship studies, based at Dundee University. These noted similar widespread flaws in the literature, limiting validity of inference and overlooking plausible alternative explanations of outcome. Particular problems were lack of details (e.g. on interventions and timings), failure to assess and adjust for confounders or biases, aggregation of outcomes (thereby missing trends) and statistical analyses (such as Chi-Sq. tests) which fail to account for dependencies of infectious outcomes. After consensus discussion, consultation with professional bodies, learned societies and editors, and independent peer review, the statement was jointly published in 2007 in the Lancet Infectious Diseases (ref 1) and the Journal of Antimicrobial Chemotherapy (ref 2), with accompanying editorials (refs 3, 4) and an exemplar paper on an antibiotic stewardship intervention (ref 5). 

The statement, like CONSORT, consists of a 22 item checklist but with item descriptors easily translatable into the wide variety of interventions, settings, designs, and statistical issues relating to infection control and antibiotic prescribing interventions and outbreak reports. The aims of the statement are to improve standards of research and publication, particularly transparency of reporting and assessment or removal of bias, and thus provide a robust evidence for policy and practice. It offers a framework for reviewers, editors and grant assessment panels, helps readers to relate papers to their practice, and facilitates synthesis of evidence.

The statement has been endorsed by Lancet ID, Journal of Antimicrobial Chemotherapy, American Journal of Infection Control, Clinical Microbiology and Infection, Epidemiology and Infection, Journal Prevention of Infection, BMC Infectious Diseases, and Antibiotic Resistance and Infection with accompanying editorials (ref 6, 7).


Checklists for authors and reviewers

Teaching materials

A number of interactive conference workshops (IFIC 2007, SHEA, ECCMID and FIS) have been held to educate participants on how to assess and design intervention studies to improve infection control and prescribing interventions. 

As a teaching resource, below are the associated papers/abstracts, which can be used as "exemplar cases" for using the ORION or CONSORT checklists. The corresponding presentations provide background, instructions, and answers to the worked examples (α indicates good compliance with statement; β indicates poor or incomplete compliance).

IFIC 2007 

Seville ESCMID postgraduate school workshop 2016


  1. Stone SP, Cooper BS, Kibbler CC, Cookson BD, Roberts JA, Medley GF, Duckworth G, Lai R, Ebriahim S, Brown EM, Wiffen PJ, Davey PG (2007) The ORION statement: Guidelines for transparent reporting of outbreak reports and intervention studies of nosociomial infection. Lancet Inf Diseases, 7(4): 282-8 (http://dx.doi.org/10.1016/S1473-3099(07)70082-8).
  2. Stone SP, Cooper BS, Cookson BD, Robersts JA, Medley GF, Duckworth G, Lai R, Ebrahim S, Brown EM, Wiffen PJ, Daviey PG. The ORION statement: guidelines for transparent reporting of Outbreak Reports and Intervention studies Of Nosocomial infection. J Antimicrobial Chemotherapy, 59(5): 833-40 (https://doi.org/10.1093/jac/dkm055)
  3. Johnson AP, McConnell J. Interventions in healthcare-associated infection: researchers urged to CONSORT with ORION. J Antimicrobial Chemotherapy, 59(5):823-4 (https://doi.org/10.1093/jac/dkm068)
  4. McConnell J, Johnson AP. Interventions in health-care-associated infection: Researchers urged to CONSORT with ORION. Lancet Inf Diseases, 7(4): 244-5 (http://dx.doi.org/10.1016/S1473-3099(07)70064-6)
  5. Fowler S, Webber A, Cooper BS, Phimister A, Price K, Carter Y, Kibbler CC, Simpson AJH, Stone SP. Successful use of feedback to improve antibiotic prescribing and reduce Clostridium difficile infection: A controlled interrupted time series. J Antimicrobial Chemotherapy, 59(5):990-5 (https://doi.org/10.1093/jac/dkm014)
  6. Stone SP, Cookson. Endorsing reporting guidelines: Infection control literature gets ahead of the game. Am J Infection Control, 44(12):1446-8 (http://dx.doi.org/10.1016/j.ajic.2016.06.038)
  7. Stone S, Cookson B. Endorsing Reporting Guidelines: the Journal of Infection Prevention helps show the way! J Infection Prevention,17(6): 264-6 (https://doi.org/10.1177/1757177416671797)