Post-Discharge Pain Management Following Fractures in Adults in the Emergency Department: The POST-PAIN Study

Background Every year, approximately 80,000 adults in Denmark sustain a fracture. A considerable proportion of these fractures do not require reduction treatment or surgery in the emergency department (ED) and are instead treated with a cast, splint or brace and discharged home. After discharge, patients must manage their pain with limited healthcare support until seeing a general practitioner or an outpatient clinic, often weeks later. Previous studies indicate that 35-37% of patients still experience pain seven days after ED discharge.

Randomized trials in adults with fracture-related pain have not shown a consistent advantage of opioids over non-opioid analgesics such as ibuprofen and paracetamol, and current guidance recommends non-opioids as first-line treatment, with opioids reserved for insufficient effect or severe pain. Nevertheless, opioids continue to be prescribed at discharge, and even short-term exposure carries a risk of dependence and misuse. Leftover opioids at home may also be a source of non-medical use among others, including young adults. Inadequately treated acute pain has been associated with psychological distress, impaired rehabilitation, an increased risk of chronic pain and additional healthcare contacts.

Knowledge about post-discharge pain management after non-reduced fractures is limited, including which analgesics are prescribed, whether patients use them as planned, patient satisfaction, and the frequency of pain-related healthcare contacts. The present study aims to address this knowledge gap. POST-PAIN is conducted by the same multidisciplinary research group as the MIST trial (procedural sedation and analgesia during reduction treatment in the ED), but constitutes an independent study with its own population, objectives and data collection.

Study design POST-PAIN is a prospective, multicenter observational cohort study conducted at seven emergency departments in Denmark. The study involves no intervention and does not change standard care. The study is reported according to the STROBE guidelines. Patient inclusion takes place from October 2026 to March 2027.

Initial treatment assessment The need for reduction treatment or surgery is assessed by the treating ED physician at the time of the ED visit, based on clinical and radiological findings and standard practice at each site. Eligibility is based on this baseline assessment. If the treatment plan changes later (for example, referral to surgery at outpatient follow-up), the patient is not excluded retrospectively, but the change is recorded as a healthcare contact.

Rationale for the study population Fractures of the hand (distal to the wrist) and foot (distal to the ankle) are not included, in order to focus on larger injuries associated with a greater pain burden after discharge.

Procedure Eligible patients are invited to participate in connection with discharge from the ED and receive oral and written information before providing written informed consent. Inclusion is carried out by local site investigators or study staff. The treating physician or nurse is not part of the inclusion staff, in order to limit performance and selection bias. A screening log in REDCap records eligible patients who decline to participate.

For seven days after discharge, participants complete a daily electronic pain diary in the research app MyCap, which sends a reminder at 19:30 each day. If electronic completion is not feasible, a paper diary is offered. A structured follow-up interview is conducted by telephone, or alternatively via Teams, 7-14 days after discharge.

To maximize follow-up, participants receive written information including the study telephone number and are encouraged to save the number in their phone. Participants receive a text message the day before the interview and another on the day of the interview with the approximate time of the call, and can reply to arrange another time. Up to three call attempts are made at different times of the day.

Data collection

Data are collected from three sources and entered into a secure, password-protected REDCap database:

• Medical records and information provided by the patient at inclusion: Dates of arrival and discharge, fracture location, analgesics prescribed at discharge, whether a written pain management plan was given, pain intensity at discharge, comorbidities and chronic pain conditions, planned follow-up at outpatient clinic, regular use of analgesics or sedatives before the injury, and basic demographic information.
• The daily pain diary: Average and worst pain intensity on a numerical rating scale (0-10), pain location, analgesic use (type, dose, time and pain before and after intake), adherence to the discharge pain plan, side effects, mood, activity level, sleep (hours, compared to normal, awakenings due to pain) and healthcare contacts due to the injury. The primary outcome is derived from the worst pain intensity reported in the day 1 diary entry.
• The follow-up interview: Satisfaction with the pain management plan and with the course of care in the ED, pain-related healthcare contacts and reasons, side effects not captured in the diary, planned follow-up at outpatient clinic, prescribed analgesics, self-initiated use of analgesics (including over-the-counter medicine and medicine obtained from relatives), the amount of unused strongly addictive pain medication, and prior analgesic use and comorbidities.

Pain threshold for the primary outcome A pain intensity of 4 or above on the numerical rating scale (0-10) was chosen as the threshold for inadequate pain control, as it corresponds to moderate to severe pain and is consistent with validated cut-off analyses. This threshold ensures clinical relevance of the primary outcome.

Sample size As this is a descriptive study, the sample size is based on the precision of the primary outcome estimate rather than hypothesis testing. Assuming an expected proportion of 45% with inadequate pain control, a two-sided alpha of 0.05 and a desired precision of plus or minus 8 percentage points, 149 patients with complete follow-up are required. Complete follow-up is defined as completion of the pain diary for all seven days and the follow-up interview. To account for an anticipated dropout of up to 50%, approximately 300-400 patients will be invited.

Statistical analysis Continuous variables are presented as mean and standard deviation, or median and interquartile range for non-normally distributed data. Categorical variables are presented as frequencies and percentages with a clearly stated denominator. Missing data are reported descriptively, including the number and proportion per variable and, where relevant, the reason (for example loss to follow-up, incomplete diary, or inability to reach the participant by telephone). A complete-case analysis is used for all outcomes unless otherwise specified, and no imputation of missing data is planned. To assess the risk of selection bias due to loss to follow-up, baseline characteristics (for example age, sex, fracture type, discharge analgesic regimen) and discharge pain intensity are compared descriptively between patients with complete and incomplete follow-up. A biostatistician will be involved in finalizing the statistical analysis plan before data collection starts.

Patient involvement The patient panel at the Emergency Department, Odense University Hospital, contributed to the study design, the selection of outcomes, user-friendliness and feasibility assessment, and reviewed the lay summary. Patients will also contribute to the development of study information materials and, if possible, to the dissemination of the results.

Limitations Inclusion relies on ED staff identifying eligible patients during routine care, so eligible patients may be missed during busy periods. This could introduce selection bias if missed patients differ from those included. After the inclusion period, a registry-based count of the eligible population will be compared with the included cohort on available baseline characteristics to assess representativeness. Follow-up is limited to the first week after discharge, and most data are self-reported.

Data protection All data are handled in accordance with the General Data Protection Regulation. Data are anonymized before publication, and personal data are stored for one year after the end of the project and then destroyed.