Traumatic injuries affect approximately 978 million people worldwide with 56.2 million requiring inpatient care. Quantitative sensory testing (QST) can be useful in predicting outcome following trauma, however the reliability of multiple QST including temporal summation (TS), heat and cold pain thresholds (HPT, CPT) and pressure pain thresholds (PPT) is unknown. We assessed intra (between day) and inter-rater (within day) reliability of QST in asymptomatic participants (n = 21), and inter-rater (within day) reliability in participants presenting with acute musculoskeletal trauma (n = 25). Intra-class correlations with 95% confidence intervals (ICC 3,2), standard error of measurement (SEM) and Bland Altman Plots for limits of agreement were calculated. For asymptomatic participants, reliability was good to excellent for HPT (ICC range 0.76-0.95), moderate to good for PPT (ICC range 0.52-0.93), with one site rated poor (ICC 0.41), and poor to excellent for TS scores (ICC range 0.20-0.91). For musculoskeletal trauma participants reliability was good to excellent for HPT and PPT (ICC range 0.76-0.86), and moderate to good reliability for TS (ICC range 0.69-0.91). SEM for HPT for both sets of participants was~1˚C and an average of 7N for asymptomatic participants and less than 8N for acute musculoskeletal trauma participants for PPT. This study demonstrates moderate to excellent intra and inter-rater reliability for HPT and PPT in asymptomatic participants and good to excellent inter-rater reliability for acute musculoskeletal trauma participants, with TS showing more variability for both sets of participants. This study provides foundations for future work evaluating the sensory function over time following acute musculoskeletal trauma.

IntroductionPain is an expected and appropriate experience following traumatic musculoskeletal injury. By contrast, chronic pain and disability are unhelpful yet common sequelae of trauma-related injuries. Presently, the mechanisms that underlie the transition from acute to chronic disabling post-traumatic pain are not fully understood. Such knowledge would facilitate the development and implementation of precision rehabilitation approaches that match interventions to projected risk of recovery, with the aim of preventing poor long-term outcomes. The aim of this study is to identify a set of predictive factors to identify patients at risk of developing ongoing post-traumatic pain and disability following acute musculoskeletal trauma. To achieve this, we will use a unique and comprehensive combination of patient-reported outcome measures, psychophysical testing and biomarkers.Methods and analysisA prospective observational study will recruit two temporally staggered cohorts (n=250 each cohort; at least 10 cases per candidate predictor) of consecutive patients with acute musculoskeletal trauma aged ≥16 years, who are emergency admissions into a Major Trauma Centre in the United Kingdom, with an episode inception defined as the traumatic event. The first cohort will identify candidate predictors to develop a screening tool to predict development of chronic and disabling pain, and the second will allow evaluation of the predictive performance of the tool (validation). The outcome being predicted is an individual’s absolute risk of poor outcome measured at a 6-month follow-up using the Chronic Pain Grade Scale (poor outcome ≥grade II). Candidate predictors encompass the four primary mechanisms of pain: nociceptive (eg, injury location), neuropathic (eg, painDETECT), inflammatory (biomarkers) and nociplastic (eg, quantitative sensory testing). Concurrently, patient-reported outcome measures will assess general health and psychosocial factors (eg, pain self-efficacy). Risk of poor outcome will be calculated using multiple variable regression analysis.Ethics and disseminationApproved by the NHS Research Ethics Committee (17/WA/0421).

In chronic whiplash associated disorders (WAD), poorer outcome is linked to early widespread sensitization (Sterling et al., 2003; Van Oosterwijck et al., 2013; Walton, MacDermid, Nielson, Teasell, Reese, et al., 2011), and following fractures, widespread pain distribution is evident soon after injury (Doménech-García et al., 2018). Due to noxious stimuli and prolonged duration of high pain intensity (Graven-Nielsen