Pain Assessment

Pain management clinicians across specialties recognize the impossibility of directly measuring pain or suffering in another person. However, this limitation does not eliminate the need for objective measures or their approximations. Pain is the most common complaint in primary care. More than 50 million individuals in the United States (US)—approximately 20% of the population—experience chronic pain, with prevalence increasing significantly among older adults. Amid rising opioid use disorder, logical and adequate pain treatment remains critical. This reality underscores the importance of adjunctive agents defined by the World Health Organization that may reduce opioid reliance and the need to measure pain alongside the effects of these therapies. Pain assessment requires distinguishing acute from chronic pain; severe pain persisting beyond 3 months generally qualifies as chronic. This distinction proves essential, as chronic pain often reflects central nervous system dysfunction rather than peripheral nociception. Maladaptive changes such as hyperalgesia and allodynia become more common. Affected tissues develop a hypertonic, ropy, and cold texture, with pain sensations shifting from sharp to dull and achy. How pain is assessed significantly influences patients’ long-term morbidity and mortality. Over 30% of patients report pain lasting longer than 6 months, highlighting the need for clinicians to employ multiple tools to characterize pain and improve symptom management accurately. Approximately 8% of adults and 6% of children experience chronic pain that substantially limits function and quality of life, with an overall 20.9% of adults in the US affected to some degree. Effective treatments differ among acute, chronic, centralized, and neuropathic pain types. Neuropathic pain affects roughly 10% of the US population and may respond better to serotonin-norepinephrine reuptake inhibitors, such as duloxetine, than to nonsteroidal anti-inflammatory drugs like ibuprofen in acute injuries. Chronic pain ranks among the leading causes of disability and lost productivity in the US, resulting in billions of dollars in economic losses. Standardized pain assessment tools offer an objective means of monitoring symptoms and recovery over time. An important aspect of pain assessment involves recognizing the impact of comorbidities and psychosocial factors that influence pain perception. Mood disorders exacerbate pain, and their treatment often leads to improvement in symptoms. A patient’s history of opioid dependence, intravenous drug use, sexual abuse, trauma, advanced age, chronic illness, and economic disparity also contributes to pain experiences. Cultural factors further influence the expression and response to pain. Ultimately, integrating standardized testing, physical examination, psychological factors, including thought and mood disorders and their impact on perception, secondary gain, abuse history, and the emotional dimensions of pain and treatment response exemplifies how medicine combines art with science. The Numeric Rating Scale (NRS) is a simple and widely used tool for quantifying pain intensity, where patients rate their pain from 0 (no pain) to 10 (worst possible pain). Despite its popularity, the NRS remains a crude and generic measure, lacking consistency and objective verification. This scale proves useful in certain contexts, such as assessing pain before and after sublingual nitroglycerin administration for cardiac angina, or evaluating simple fractures in older patients, where a pain rating of 4 may correlate with respiratory suppression. However, the NRS has limitations. For example, patients with myofascial pain or uncertain diagnoses who report extreme pain (eg, 10/10) despite stable vital signs and evidence of analgesic administration may raise concerns for drug-seeking behavior. In cases involving an “aggressive escort” or a quiet patient, clinicians should note the language used, avoid assumptions, and maintain vigilance. Oral medications should be administered under supervision to prevent “sharing” or diversion, as “pocketing” pills for later use or trafficking is common. The presence of an escort dominating communication warrants careful assessment for potential abuse or trafficking. The Visual Analogue Scale functions similarly to the NRS but may incorporate pictorial elements to assist patients who do not share the clinician’s language. This scale consists of a line with endpoints labeled “no pain” and “worst possible pain,” where patients mark their pain level. The score corresponds to the distance from “no pain” to the mark. The VAS shares the same limitations as the NRS. The Wong-Baker FACES Pain Rating Scale is designed for pediatric individuals who may be nonverbal in acute settings and can also be adapted for use with adults who have communication difficulties. (Source: Wong Baker FACES History, 2016) The Nonverbal Pain Scale is particularly useful in intensive care units to assess pain in nonverbal adults, such as intubated but not fully sedated patients. The Behavioral Pain Scale offers an observational method for assessing pain in patients who are sedated or unconscious. This tool evaluates facial expressions, upper limb movements, and compliance with mechanical ventilation. Effective use requires considerable experience and interpretation within the clinical context, including the interpretation of vital signs. For example, tachycardia may indicate distress or resolution, depending on the patient’s medication, such as β-blockers or calcium channel blockers, which are commonly used among patients in the intensive care unit, regardless of ventilation status. The Short Form Health Survey 36 consists of 36 questions assessing multiple health domains, including physical functioning, role limitations, bodily pain, general health, vitality, social functioning, emotional role, and mental health. Although not solely a pain assessment tool, it serves as an objective measure of quality of life in patients with chronic pain. This tool may be used to guide chronic treatment decisions. Opinions vary regarding its utility across different populations. The common “squeeze my hand where it hurts most” technique is the worst tool. The McGill Pain Questionnaire (MPQ) is a self-reported instrument designed to assess both the quality and intensity of pain. This questionnaire presents 78 descriptors divided into sensory, affective, and evaluative categories, allowing patients to select words that best characterize their pain experience. The MPQ provides a quantitative measure useful for tracking pain over time and evaluating treatment effectiveness. The value of the MPQ lies in differentiating emotional-somatic descriptors such as “agonizing,” “dreadful,” and “torture” from sensory terms like “sharp,” “dull,” “throbbing,” or “constant.”