Our results indicate that perceived pain intensity is an independent predictor of chronic pain after DRF, while pain with movement was is more predictive of disability. Specifically, individuals reporting pain intensity of ≥3 on PAR and ≥ 6 on MEP at 2-months after DRF are at high risk of experiencing moderate or severe pain at 6-, and 12 months following the injury. The higher PAR at 2-months is a stronger predictor of persistent pain, while MEP was a stronger predictor of disability at 6- and 12 months after DRF. Our research started with a hypothesis that the items of the PRWE that routinely measure PAR and MEP might be a useful indicator of condition irritability. While irritability is an important concept, the ratio of these two pain items was not a useful predictor of pain and disability over a longer term after DRF. We attribute this to unique aspects of using ratios.
Previous research has demonstrated that pain intensity obtained within 2-weeks of DRF is predictive of poor pain outcomes a year after DRF [8, 16, 25]. High pain levels in the initial few days of injury, when the wrist/hand is immobilized and joint movements are restricted, should indeed serve as a warning sign for clinicians. While this knowledge is useful, physiotherapists may not be involved in the case management at this early stage. We focused on the prediction based on scores from the early mobilization phase where patients would typically present to physiotherapy which occurs at approximately 6–8 weeks after the injury, when the fracture has sufficiently healed and immobilization devices are removed . Knowledge concerning the associations between pain intensity reported during or within few days after initiating rehabilitation of DRF with poor pain and function outcomes after the injury has greater utility for physiotherapists. Such knowledge can enable physiotherapists to identify a risk profile for poor outcomes for an individual patient seeking rehabilitation of DRF. Since not every patient requires in-clinic supervised therapy and those with complications or at risk of adverse outcomes are more likely to require supervised rehabilitation after DRF , abilities to determine the risk profile for each patient can serve as an extremely useful clinical tool for physiotherapists in developing an individualized plan of care for each patient with DRF.
Our study showed that 2-months scores for PAR (score of ≥3/10), MEP (score of ≥6/10), and MEPR ≥8/10 are prognostic indicators of adverse outcomes after DRF. Previous research either used average pain intensity  or score on pain scales [8, 25] as prognostic indicators of chronic pain after DRF. Pain at rest and MEP are very useful pain indicators for understanding pain experience. High scores of PAR at 2- months after DRF, especially when the fracture has healed, can be one of the indicators of the presence of nociplastic pain or centrally mediated pain behavior , although a patient may have multiple pain mechanisms occurring simultaneously such as infection, hardware problems, and CRPS that might result in high pain. Further investigation would delineate whether patients have other indicators of centrally mediated pain that might require a therapy plan that target central pain , or other contributing factors. Conversely, MEP indicates irritability of pain with movement. Intense pain during movement might indicate to therapists that patients would be unlikely to complete their assigned therapeutic exercises which would inevitably a delay their recovery. Dynamic causes of pain including ligament, muscle or nerve injury, hardware issues, malalignment/union, or aggravation of underlying arthritis. Further examination would be required of these potential contributors. Movement evoked pain can also have psychological contributors and may contribute to development or reinforcement of fear avoidant behavior. This may explain why, movement-evoked was a better predictor of disability .
Using the cutoffs identified in this study for 2-months PAR (≥3/10) and/or MEP (≥7/10) will allow physiotherapists to consistently screen for risk of adverse outcomes after DRF, and will guide additional examinations which will support customized treatment plans. Having demonstrated that someone is presenting at elevated risk, physiotherapists will modify the initial assessment to look for potential physical and psychological factors that could be contributing to elevated pain. Depending on the findings of these examinations, therapist may implement modified treatment plans that target modifiable risk factors. Careful attention to the presence of edema and additional pain modalities, may be needed for those with higher pain experiences. Therapist may initiate cognitive reshaping type discussions with patients to align recovery expectations and educate patients in pain neuroscience . Educating patients about the pain neuroscience (understanding of fear avoidance, pain catastrophization, patient expectations, cognitions, and beliefs) and explaining the relationships between pain and movement as they initiate physiotherapy for rehabilitation of DRF can reduce pain-related anxiety [32, 33]. Empowering patients to take an active role in their recovery and providing self-management skills for their pain can assist them with greater success in performing during therapeutic exercises and functional daily living tasks. Another approach is to progress wrist/hand exercises  in a graduated manner such that they optimize the recovery and minimize the setbacks that may arise from severe aggravation of pain, while providing greater self-efficacy  through accomplishment .
One of the other premises of this study was to examine whether MEPR, which is the ratio of MEP and PAR, could provide a useful indicator of the underlying irritability of the healing fracture. We conceptualized that the lower a MEPR, where pain with movement was similar to pain at rest would predict better recovery DRF. Physiotherapists commonly seek information about MEP and PAR during clinical examination. Pain irritability is a core construct in planning the intensity of rehabilitation programs and for progression.
Based on our results, the MEPR did not yield any meaningful information in identifying risk for persistent, moderate, or severe pain or poor wrist/hand function after DRF. Results suggested that 2- months MEPR scores, while showing some associations with pain and disability, did not discriminate between those who will or will not develop chronic pain at 6- and 12 months after DRF (AUC between 0.50–0.60). While irritability may be an important construct in assessing the impact of pain on overall function and calibrating exercise interventions, the MEPR ratio may not be the best measure to assess pain irritability. There are other reasons to support the finding that MEPR did not appear to have prognostic value in assessing the risk of poor outcome after DRF. Firstly, 0–10 scales for MEPR extracted from dividing two 0 to 10 scales (PAR and MEP) may be problematic from a measurement perspective. For example, a person with MEP score of 2/10 and PAR score of 1/10 is very different than someone who presents with PAR score of 5/10 and MEP score of 10/10, although in both cases the ratio would be same. Because most patient reported outcome measures are ordinal and not interval level data, mathematical operations can be problematic. Clinically, a doubling of pain when pain is at a very low level may not be clinically significant because it is still low; whereas, someone in moderate pain whose pain is doubled can be then in severe pain. Further, since the ratio is made up of two measures, each with its own source of measurement errors, computing the ratio may be subject to increased measurement errors. Finally, the scores for ratios such as the MEPR exist in a smaller range. Given these measurement considerations, we advise clinicians to evaluate irritability by considering PAR and MEP separately.
There are a few limitations of this study. Firstly, this was a retrospective cohort study where data was collected process prospectively but retrieved for the study analysis at a later date. This means that variables we may have analysed had they existed in the database such as fracture type, surgical management and use of pain medications were not present. These may have contributed additional explanatory power and/or modified the impact of the variables and models. However, since the information we did use was easily available to therapists upon, this information is most consistently able to be used by therapists in treatment planning. We did not have data on the nature of the rehabilitation services that patients received and so could not control for that. Our study did not include psychosomatic or behavioral factors, which are known to impact the recovery after DRF [37, 38] while assessing the associations of the PAR or MEP with chronic pain after DRF. Nonetheless, we believe that the impact of psychosomatic or behavioral factors on worse pain experience may have contributed to PAR and MEP scores. Therefore, using these scores for prognostication after DRF can be considered a comprehensive and simpler approach for physiotherapy practice. Secondly, we did not calculate the sample size because this was a retrospective analysis. However, post hoc analysis indicated we were sufficiently powered.