Dr Carol Hawley, Dr Tom deBurgh, Colonel Robert Russell, Andrew Mead Traumatic Brain Injury Among British Armed Forces Serving in Iraq and Afghanistan: Data from JTTR Dr Carol Hawley, Dr Tom deBurgh, Colonel Robert Russell, Andrew Mead

Joint Theatre Trauma Registry Unique Access to JTTR Records every military casualty killed or injured on duty and seen by the Trauma team Records kept from 2003 at start of Iraq War (2440 casualties to Sept. 2011) How and where injured, clinical information, treatment given Predictor Variables: Injury severity scores: TRISS, AIS, NISS, ASCOT Outcome Variables: Fatality/Survivor; Hospital, Rehabilitation, Return to Duty

History of the paper Analysis as per study protocol and submission to Journal of Head Trauma Rehabilitation January 2013 Returned with comments from ‘Statistical’ Reviewer. Wanted different methods and asked us to use tests never heard of. “Point- biserial correlations, the 2-step method of Belsley et al. Use BIC and AIC to choose the best injury severity variable.” Statistical Seminar !! Discussion with Andrew Re-did analysis according to ‘Stats’ Reviewer request. Resubmitted V2

History continued... Returned from ‘Statistical’ reviewer – still not happy, wants different analysis and different tests...... Another Statistical Seminar – chat with Sandy – arranges one-to-one with Andrew We share the database and work on the latest set of ‘Stats’ Reviewer requirements. Andrew added as co-author and writes detailed explanation of statistical analysis (simple logistic regression and multiple logistic regression) Resubmitted V3

Continued... ‘Stats’ reviewer still not happy. Editor steps in and recommends we remove the multiple regression to pacify the reviewer. Andrew writes response to ‘Stats’ Reviewer. Revise and resubmit V4. ACCEPTED ! But, a compromise and shows how a ‘statistical’ reviewer can force researchers to alter the methods prescribed in a study protocol. Without this statistical seminar series and Andrew’s help doubt would have succeeded. Publication soon, meeting University Press Officer later today, high impact expected.

Statistical Consultancy and Collaboration Understand aims of study and dataset Explore and explain reviewers suggestions ‘point biserial correlation’ – correlation where one variable is binary, but calculations identical to standard Pearson product-moment correlation! ‘logistic regression’ – takes correct account of distribution of the response (binary – survival) ‘issues with multicollinearity (Belsley 2-step method)’ – SPSS does exactly what reviewer wanted, but not explicit in output!

Statistical Consultancy and Collaboration Re-analysis considering a wider range of models and providing more detailed interpretation Further exploration of data Identification of data inconsistencies, effectively as a result of ‘missing’ observations Refining of records to be included More detailed description of data analysis approaches Identification of tests used to select models, using output produced by SPSS Using available output to ‘better’ explain the analysis performed

Interactions with Editors and Reviewers Compromise often needed on statistical issues in publications Reviewers often have a limited (‘biased’) view on appropriate approaches Not necessarily based on statistical expertise but often on past experience! Possibly based on what their ‘favourite’ package produces Different packages produce different outputs, but generally perform the same analysis! Journals (Editors) are often reluctant to publish ‘novel’/unusual statistical approaches Correct/appropriate methods applied here, but ‘too statistical’ for journal? Reviewers view accepted above statistical expertise of co-author?