Another important dimension of pain is its effects beyond strictly physiological functioning. Pain is currently viewed as a multi-dimensional, multi-level process similar in many ways to other disease processes which may start with a specific injury but which can lead to a cascade of events that can include physical deconditioning, psychological and emotional burdens, and dysfunctional behavior patterns that affect not just the sufferer, but their entire social milieu (illustrated in Figure 2). 16 Although pain is expected after injury or surgery, the patient pain experience can vary markedly. The intensity of pain can be influenced by psychological distress (e.g., depression or anxiety), heightened illness concern, or ineffective coping strategies regarding the ability to control pain and function despite it. 17 It may also be shaped by personality, culture, attitudes, and beliefs.
Assessing the impact of pain on functional status and sleep and screening for mental health conditions potentially related to pain or treatment adherence (e.g., depression, anxiety, and memory issues) may provide useful information for pain management. 19 Depression in older patients, for example, sometimes presents with somatic complaints of pain. Pain complaints may resolve when the underlying depression is treated. Patients can also be screened for known risk factors for OUD (see below). Tools Many tools have been developed to document and assess pain. Initial approaches to assessing pain severity use a numerical rating scale (NRS) rating pain from 0 (no pain) to 10 (worst pain you can imagine) (some scales use a 0 to 100 scale). Such scales are often used in clinical trials of pain therapies, and the minimal clinically important difference using these scales is generally considered a 20%-30% change from baseline (i.e., 2-3 points on a 0-10 scale or 20-30 points on a 0-100 scale). 20 Multidimensional tools, such as those described below, include questions relating to quality of life and participation in daily activities. Such tools can provide a more comprehensive approach to assessing pain and response to treatment. The selection of a pain assessment tool must balance the comprehensiveness of the assessment obtained with the time and energy required to use the tool in a real-world practice setting. Brief pain inventory The Brief Pain Inventory (BPI) is used frequently in clinical trials to assess pain. Specifically developed for patients with chronic pain, the BPI more fully captures the impact of pain on patient function and quality of life than simple VAS scales. 21 By including a pain map, the BPI allows tracking of the location of pain through the course of management. The BPI is self-administered but somewhat time-consuming, which may limit its role in a busy clinical practice. PEG scale The PEG scale (Pain average, interference with Enjoyment of life, and interference with General activity) is a three-item tool based on the BPI and is practical for clinical practice (Figure 3).
Evaluating pain
Take a history The patient’s self-report is the most reliable indicator of pain. 18 Physiological and behavioral signs of pain (e.g., tachycardia, grimacing) are neither sensitive nor specific for pain and should not replace patient self-report unless the patient is unable to communicate. Therefore, talking to patients and asking them about their pain (i.e., obtaining a “pain history”) is integral to pain assessment. The pain history usually is obtained as part of the patient history, which includes the patient’s past medical history, medications, habits (e.g., smoking, alcohol intake), family history, and psychosocial history. Obtaining a comprehensive history provides many potential benefits, including improved management, fewer treatment side effects, improved function and quality of life, and better use of health care resources.
Figure 2. The Biopsychosocial Model of Pain 16
Figure 3: PEG scale 22
What number best describes your pain on average in the past week?
0
1
2
3
4
5
6
7
8
9
10
No pain
Pain as bad as you can imagine
45
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