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How are risk ratios reported in orthopaedic surgery journals? A descriptive study of formats used to report absolute risks
  1. Dafina Petrova1,2,
  2. Alexander Joeris3,
  3. María-José Sánchez1,2,4,
  4. Elena Salamanca-Fernández1,2,4,
  5. Rocio Garcia-Retamero5,6
  1. 1 Escuela Andaluza de Salud Pública, Granada, Spain
  2. 2 Instituto de Investigación Biosanitaria ibs.GRANADA, Universidad de Granada, Granada, Spain
  3. 3 AO Clinical Investigation and Documentation, Duebendorf, Switzerland
  4. 4 CIBER de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
  5. 5 Mind, Brain, and Behavior Reseach Center (CIMCYC), Department of Experimental Psychology, University of Granada, Granada, Spain
  6. 6 Harding Center for Risk Literacy, Max Planck Institute for Human Development, Berlin, Germany
  1. Correspondence to Dr Alexander Joeris; alexander.joeris{at}


Purpose The numerical format in which risks are communicated can affect risk comprehension and perceptions of medical professionals. We investigated what numerical formats are used to report absolute risks in empirical articles, estimated the frequency of biasing formats and rated the quality of figures used to display the risks.

Design Descriptive study of reporting practices.

Method We randomly sampled articles published in seven leading orthopaedic surgery journals during a period of 13 years. From these, we selected articles that reported group comparisons on a binary outcome (eg, revision rates in two groups) and recorded the numerical format used to communicate the absolute risks in the results section. The quality of figures was assessed according to published guidelines for transparent visual aids design.

Outcome measures Prevalence of information formats and quality of figures.

Results The final sample consisted of 507 articles, of which 14% reported level 1 evidence, 13% level 2 and 73% level 3 or lower. The majority of articles compared groups of different sizes (90%), reported both raw numbers and percentages (64%) and did not report the group sizes alongside (50%). Fifteen per cent of articles used two formats identified as biasing: only raw numbers (8%, ‘90 patients vs 100 patients’) or raw numbers reported alongside different group sizes (7%, ‘90 out of 340 patients vs 100 out of 490 patients’). The prevalence of these formats decreased in more recent publications. Figures (n=79) had on average two faults that could distort comprehension, and the majority were rated as biasing.

Conclusion Authors use a variety of formats to report absolute risks in scientific articles and are likely not aware of how some formats and graph design features can distort comprehension. Biases can be reduced if journals adopt guidelines for transparent risk communication but more research is needed into the effects of different formats.

  • orthopedics
  • general surgery
  • scientific reporting
  • risk communication
  • visual aids

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  • Contributors DP, AJ and RG-R contributed to the design of the study. DP, ES-F and RG-R collected and analysed the data. All authors interpreted the results and revised the manuscript (DP produced the first draft). All authors approved the final version of the manuscript.

  • Funding DP is supported by a Juan de la Cierva Fellowship (FJCI-2016-28279) from the Spanish Ministry of Economy, Industry, and Competitiveness. The presented study was partially funded by the AO Foundation via the AO Clinical Investigation and Documentation network and by the Spanish Ministry of Economy and Competitiveness (Spain) (PSI2011-22954 and PSI2014-51842-R).

  • Disclaimer The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Data are publicly available on the Open Science Framework: