Pain Assessment

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Pain Phases

When assessing pain, it is important to recognise the differences between acute and persistent/chronic pain and the implications for assessment and management of the patient:

1. Acute - in the acute pain phase performance of a comprehensive assessment using reliable and validated tools to prevent the onset of chronicity is of utmost importance.
   
2. Persistent/Chronic - when persistent pain presents it is important to gather an understanding of factors contributing to the persistence of pain.

Pain Assessment

Often when assessing pain we use a biopsychosical approach for assessment of pain and disability as it accounts for the multidimensional nature of pain in domains relevant to physical therapy practice.

A biopsychosocial assessment should seek to identify the following:

• Bio (triage and identification of the pathology - Red Flags)
• Psycho (psychological distress, fear/avoidance beliefs, current coping methods and attribution - Yellow an Orange Flags)
• Social (work issues, family circumstances and benefits/economics - Blue and Black Flags)

During our assessment we must account for the multidimensional nature of pain by including appropriate assessment measures for primary domains including:

• Sensory
• Affective
• Cognitive
• Physiological
• Behavioral

The effects of pain can be complex and can traverse many intersecting domains.

Pain Measures

Despite the difficulty inherent to measuring pain, there are a number of accepted tools for tracking pain-related treatment outcomes. The proper use of these tools can allow clinicians and researchers to demonstrate both statistically and clinically significant treatment effects.

Commonly used measures for different pain dimensions include:

• Self-report measures
• Physical performance measures including Functional Capacity Evaluations (FCEs)
• Physiological/autonomic response measures 
  

Chronic pain has multiple effects on patients, so outcome measures cover several domains:

• Pain Quantity
• Pain Interference
• Physical Functioning
• Emotional Functioning
• Quality of Life
• Patient reported global rating

These measures each have their own strengths and limitations for different pain dimensions which we must recognise:

Self Report Measures

Pain Scales:

• Numerical Pain Rating Scale (NPRS)
• Visual Analogue Scale (VAS)
• Verbal Raiting Scale (VRS)
• Patient Global Impression of Change

Pain Interference:

• Roland & Morris Disability Index
• Oswestry Low Back Pain Disability Questionnaire

Physical Function:

• Brief Pain Inventory

Quality of Life:

• Euroqol 5D

Emotional Distress / Functioning:

• Beck Depression Inventory (BDI-li)
• Centre for Epidemiological Studies-Depression Scale
• Hospital Anxiety and Depression Scale (HADS)
• Profile of Mood States
• The Pain Self-Efficacy Questionnaire (PSEQ)
• Short-Form McGill Pain Questionnaire (SF-MPQ)
• Short-Form McGill Pain Questionnaire 2 (SF-MPQ-2)
• Brief Pain Inventory - Short Form
• West Haven-Yale Multidimensional Pain Inventory
• Treatment Outcomes of Pain Survey
• Short Form-36 Bodily Pain Scale
• painDETECT
• Neuropathic Pain Questionnaire (NPQ)
• 4-Item Pain Intensity Measure (P4)
• ID-Pain
• Functional Pain Scale
• Pain Catastrophizing Scale
• STarT Back Screening Tool

An individual’s ability to persist through a questionnaire depends on a number of individual and environmental factors (eg, attention span, interest in the scale, dedication to the project, incentives, outside distracters, or item complexity).  Conservatively, questionnaire packets should be able to be completed by the majority of individuals in under 25 minutes. These longer packets may also be combined with more frequently administered, single-item measures to provide a balance of depth of information and temporal resolution

Physical Performance Measures

Many physical functioning and performance tests, such as range-of-motion, exist and have been used as a proxy for objective pain measurement. Examples of standardised performance/functioning tests for chronic pain include the following:

• The loaded forward-reach test for chronic back pain
• Timed “Up & Go” test for osteoarthritis
• Grip strength for rheumatoid arthritis
• The Abbey Pain Scale for the observation of physical presentation in non-verbal individuals e.g. those with dementia

Pain is just one component of physical performance, and other factors, such as fear of pain, may heavily impact performance scores. Therefore, although clinic-based tests of functioning can complement self-reported pain measures in chronic conditions, they are not useful as a pain-report substitute.

Physiological/Autonomic Response Measures

Younger states that the field of pain management would benefit enormously from an objective, physiologic marker of pain and describes how several physiologic variables, such as skin conductance and heart rate, have been measured for this purpose. In general, however, these markers do not correlate strongly enough with pain to warrant their use as a surrogate measure of pain. Pain can exist in the absence of changes in these measures, and these measures can fluctuate drastically with no change in pain. These peripheral measures indicate general autonomic activity, which can be influenced by many factors other than pain, such as other forms of arousal. Also, treatments may directly impact those physiologic variables, further reducing their reliability as a clean pain measure. Work still continues in this area, with tests of more sophisticated measurement approaches or biomarkers of pain intensity.

Individualized Assessment

It is important to modify pain assessment strategies to match inherent variability associated with the patient's clinical presentation:

• Individual factors (e.g. age, sex, etc.)
• Sociocultural influences (e.g. spirituality, ethnicity, etc.)
• Clinical characteristics of pain (e.g. duration, anatomical location, etc.)
• Pain type and state (e.g. neuropathic pain, cancer pain, etc.)
• Vulnerable populations (e.g. communication barriers, cognitive impairment etc.)

Outcomes of Pain Assessment

Following assessment of pain suitable management strategies can be implemented.  However, as always, it is important to understand the need to:

1. Monitor and review the effectiveness of treatment/management and modify treatment and management strategies appropriately.
2. Refer to relevant health professional as appropriate and in a timely manner.
   

An excellent ressource on this topic is the British Pain Society. You can find a compilation of their Pain Outcome Measures here:

https://www.britishpainsociety.org/static/uploads/resources/files/Outcome_Measures_January_2019.pdf

Resources

• Dansie EJ, Turk DC. Assessment of patients with chronic pain. British journal of anaesthesia. 2013 Jul 1;111(1):19-25.
• Jarred Younger, Rebecca McCue and Sean Mackey. Pain Outcomes: A Brief Review of Instruments and Techniques. Curr Pain Headache Rep. 2009 February ; 13(1): 39–43.