Residency · Residency · Chronic Pain Management
Comprehensive Pain Assessment
Overview
The pain history is the single most important diagnostic tool in chronic pain medicine. A structured, systematic assessment identifies pain mechanisms, functional impact, psychosocial contributors, and red flags requiring urgent investigation. The goal is not simply to quantify pain intensity but to construct a biopsychosocial formulation that guides individualized, mechanism-based treatment.
Structured Pain History
Pain Characteristics (OPQRST Framework)
The OPQRST framework provides a systematic approach to characterizing pain. Onset asks whether the pain began acutely, subacutely, or insidiously, and what inciting event triggered it -- trauma, surgery, or spontaneous onset -- as well as its temporal relationship to illness, injury, or psychosocial stressors. Palliating and provoking factors identify what makes the pain better (rest, heat, ice, medications, positioning) and worse (movement, weight-bearing, stress, weather, time of day).
Quality is the single most diagnostically useful element of the pain history. Aching, throbbing, or pressure-like pain suggests a nociceptive mechanism. Burning, shooting, or electric/lancinating pain suggests a neuropathic mechanism. Deep, diffuse, migratory pain associated with fatigue suggests a nociplastic mechanism.
Region and radiation document the anatomical distribution, whether the pattern is dermatomal or non-dermatomal, and whether it is unilateral or bilateral. A body map diagram is invaluable for this purpose. Severity should capture current, best, worst, and average pain levels over the past week using a numeric rating scale (NRS 0-10). Temporal pattern records whether the pain is constant or intermittent, its diurnal variation, its relationship to activity, and whether the trajectory is progressive, stable, or improving.
Pain Duration and Trajectory
Pain is classified as acute (less than one month), subacute (one to three months), or chronic (greater than three months, per IASP criteria). The trajectory -- improving, stable, worsening, or fluctuating -- should be documented, along with episodes of acute-on-chronic exacerbation (breakthrough pain).
Associated Symptoms
Associated symptoms provide critical diagnostic clues. Neurological symptoms including numbness, tingling, weakness, and bowel or bladder dysfunction point toward nerve involvement. Autonomic features such as color changes, temperature asymmetry, and sweating abnormalities raise concern for CRPS. Constitutional symptoms -- weight loss, fever, and night sweats -- suggest malignancy or infection. Systemic features like morning stiffness lasting more than 30 minutes (inflammatory arthritis), fatigue, sleep disturbance, and cognitive dysfunction (fibromyalgia or nociplastic features) help classify the pain mechanism.
<image>Clinical assessment body map diagram showing anterior and posterior views of the human body with color-coded pain distribution patterns: dermatomal distribution in one area suggesting neuropathic pain, localized joint region suggesting nociceptive pain, and widespread bilateral distribution suggesting nociplastic pain, with a legend linking each pattern to its mechanistic classification</image>
Medication History
A thorough medication history covers current analgesics (drug, dose, frequency, duration, efficacy, side effects, and adherence) and all prior analgesics with reasons for discontinuation -- whether inefficacy, adverse effects, or insurance issues. Opioid-specific history deserves particular attention: the current opioid dose should be calculated in morphine milligram equivalents (MME), along with the duration of opioid therapy, evidence of tolerance, opioid-induced hyperalgesia, or aberrant behaviors. Prescription drug monitoring program (PDMP) review is mandatory in most jurisdictions. Non-pharmacological treatments that have been tried -- physical therapy, chiropractic care, acupuncture, injections, surgery, neuromodulation, and psychological interventions -- should all be documented, along with supplements and over-the-counter medications.
Functional Assessment
Chronic pain is defined not only by duration but by its functional impact. Assessment should span multiple domains: physical function (mobility, activities of daily living, gait, exercise tolerance, and sleep quality), work function (current employment status, work modifications, disability status, and time off work), social function (relationships, social activities, isolation, and caregiver burden), and role function (ability to fulfill family, parental, and community roles).
Standardized tools quantify functional impairment: the Pain Disability Index (PDI) provides a general measure, the Oswestry Disability Index (ODI) is the standard for back pain, and the DASH is used for upper extremity conditions. Functional goals should be patient-centered and specific -- "I want to walk 30 minutes daily" is far more meaningful and measurable than "I want to be pain-free."
Psychosocial Screening
Psychological Factors
| Domain | Screening Tool | Positive Threshold | Prevalence in Chronic Pain |
|---|---|---|---|
| Depression | PHQ-9 | ≥10 (moderate) | 30–50% |
| Anxiety | GAD-7 | ≥10 (moderate) | 20–40% |
| Pain catastrophizing | PCS | ≥30 | 25–35% |
| Fear-avoidance | TSK / FABQ | TSK ≥37 | 20–40% |
| PTSD | PC-PTSD-5 | ≥3 | 10–30% |
| Insomnia | ISI | ≥15 (moderate) | 50–80% |
| Opioid risk | ORT / SOAPP-R | ORT ≥8 (high risk) | Variable |
| Substance use | CAGE-AID / DAST-10 | CAGE-AID ≥2 | 15–25% |
Screening for psychological comorbidities should be routine. Depression (PHQ-9 or PHQ-2 screening) has a prevalence of 30-50% in chronic pain populations. Anxiety (GAD-7) includes generalized anxiety, panic disorder, and health anxiety. Pain catastrophizing, measured by the Pain Catastrophizing Scale (PCS), is the strongest psychological predictor of disability and poor treatment response. Fear-avoidance is assessed with the Tampa Scale of Kinesiophobia (TSK) or Fear-Avoidance Beliefs Questionnaire (FABQ). PTSD screening (PC-PTSD-5) is particularly relevant in trauma-related pain. Sleep disturbance, assessed with the Insomnia Severity Index (ISI), has a bidirectional relationship with pain -- poor sleep worsens pain, and pain disrupts sleep. Adverse childhood experiences (ACEs) are associated with increased risk of chronic pain, central sensitization, and functional somatic syndromes.
Social Factors
Compensation and litigation represent real contextual factors that may influence behavior and recovery trajectory, though secondary gain should not be used to dismiss a patient's pain. Social support, substance use history (screened with CAGE-AID or DAST-10), and opioid risk (assessed with the Opioid Risk Tool or SOAPP-R) all inform the treatment plan.
<image>Biopsychosocial assessment wheel diagram divided into three sectors -- biological, psychological, and social -- each containing specific assessment domains: biological sector shows pain mechanism identification, comorbidities, medications, and physical examination findings; psychological sector shows mood, catastrophizing, fear-avoidance, coping strategies, and trauma history; social sector shows employment, compensation, relationships, cultural factors, and healthcare access, with arrows connecting interacting domains</image>
Red Flags in Chronic Pain
Red flags mandate urgent investigation and potential emergent referral.
Spinal Red Flags
Cauda equina syndrome -- saddle anesthesia, bilateral leg weakness, bowel and bladder dysfunction -- is a surgical emergency. Spinal infection should be suspected with fever, IV drug use history, recent spinal procedures, immunosuppression, or progressive neurological deficit. Malignancy is suggested by age over 50 with new back pain, history of cancer, unexplained weight loss, pain at rest or worsening night pain, or failure to improve with conservative care. Fracture should be considered after significant trauma or in the setting of osteoporosis, steroid use, or age over 70. Progressive neurological deficit, including acute or progressive motor weakness and myelopathic signs (hyperreflexia, clonus, Babinski sign, gait ataxia), requires urgent evaluation.
Systemic Red Flags
Unexplained weight loss, night sweats, and fever raise concern for malignancy or systemic disease. Pain that is relentlessly progressive and unresponsive to analgesics, new-onset pain in a patient with known malignancy, and signs of systemic inflammatory disease (morning stiffness exceeding one hour, elevated inflammatory markers, multi-joint involvement) all warrant further investigation.
Vascular Red Flags
Acute limb ischemia presents with pain accompanied by pallor, pulselessness, poikilothermia, paresthesias, and paralysis. Aortic dissection or aneurysm presents with tearing pain radiating to the back and a pulse differential between limbs.
Special Populations
Geriatric Patients
Older adults commonly underreport pain. Observational pain scales such as PAINAD should be used for patients with dementia. Altered pharmacokinetics -- reduced renal and hepatic clearance and increased sensitivity to CNS-active drugs -- require dose adjustments. Polypharmacy and drug interactions are highly prevalent. Acetaminophen, topical agents, and non-pharmacological approaches should be prioritized, with cautious use of NSAIDs and opioids.
Pediatric Chronic Pain
Chronic pain affects 20-35% of children and adolescents worldwide. Functional pain syndromes are common, and the biopsychosocial model is essential. Family dynamics and parental catastrophizing significantly influence outcomes, making family-based interventions an important component of treatment.
Patients with Substance Use Disorders
Pain is undertreated in this population due to stigma and clinician discomfort. It is critical to distinguish physical dependence (an expected pharmacological adaptation), tolerance (the need for increasing doses to achieve the same effect), and addiction (compulsive use despite harm). Coordination with addiction medicine is important, and buprenorphine should be considered for combined management of pain and opioid use disorder.
Constructing a Pain Formulation
A complete pain assessment should culminate in a pain formulation that integrates six elements: the specific pain diagnosis or diagnoses (structural and pathological diagnoses where identifiable), the pain mechanism or mechanisms (nociceptive, neuropathic, nociplastic, or mixed), contributing psychological factors (depression, catastrophizing, fear-avoidance, trauma), contributing social factors (work status, compensation, social support, substance use), functional impact (specific domains affected and baseline functional level), and treatment goals (patient-centered, specific, measurable, achievable functional targets).
<image>Clinical flowchart for comprehensive pain assessment starting with structured pain history at the top, branching into pain mechanism classification (nociceptive, neuropathic, nociplastic), parallel psychosocial screening pathway, red flag identification checkpoint with urgent referral pathway, converging into an integrated biopsychosocial pain formulation, and ending with mechanism-based treatment planning at the bottom</image>
Clinical Pearls
Pain quality descriptors are the most diagnostically useful element of the pain history: burning, shooting, or electric qualities should trigger neuropathic pain evaluation, while diffuse aching with fatigue and sleep disturbance suggests nociplastic mechanisms. Always calculate the current opioid dose in morphine milligram equivalents (MME) and check the prescription drug monitoring program (PDMP) at every visit -- this is both a clinical and medicolegal standard of care. Pain catastrophizing, measured by the PCS, is the strongest modifiable psychological predictor of chronic pain disability and poor treatment response, and screening for it should be as routine as screening for depression. A pain assessment without functional goal-setting is incomplete -- "reducing pain by 2 points" is less meaningful than "returning to 30 minutes of daily walking" as a treatment target.
References
- Dansie EJ, Turk DC. Assessment of patients with chronic pain. Br J Anaesth. 2013;111(1):19-25.
- Edwards RR, Dworkin RH, Sullivan MD, Turk DC, Wasan AD. The role of psychosocial processes in the development and maintenance of chronic pain. J Pain. 2016;17(9 Suppl):T70-T92.
- Chou R, Qaseem A, Snow V, et al. Diagnosis and treatment of low back pain: a joint clinical practice guideline from the ACP and APS. Ann Intern Med. 2007;147(7):478-491.
- Turk DC, Melzack R. Handbook of Pain Assessment. 3rd ed. New York: Guilford Press; 2011.
