Pain Measurement in Pediatric Patients: A Look at Functional Pain Scales

By Amber Borucki, MD
Director, Pediatric Anesthesia Pain Services
Assistant Clinical Professor
Department of Anesthesia and Perioperative Care
University California San Francisco

Pain assessment in patients of any age can be challenging due to the inherent subjective definition of pain as an “unpleasant sensory and emotional experience.”  Each person’s unique experience of pain can be infinitely varied based upon several different patient-specific and injury-specific risk factors such as level of acute nociceptive or neuropathic tissue injury, presence of chronic pain prior to acute insult, pain memories or experiences, psychological disorders, presence of pain coping skills, genetic vulnerabilities to pain, environmental factors that maintain pain (psychosocial issues, socioeconomic factors), cultural perceptions of pain, and gender identity and sex.  Due to these many variables in the development and maintenance of pain, the evaluation of pain can be quite complex. 

A multidimensional review of these potential risk factors could perhaps provide the most detailed evaluation of pain, however due to necessity of time, efficiency, and brevity in clinical practice the most common pain measurement tools used employ collecting ordinal data by way of subjective self-report scores (Wong-Baker, NRS, etc.).   For patients who are cognitively able to participate in self reporting, this is considered the gold standard for pain measurement. For patients who (due to age or cognitive ability) are unable to self-report, objective measures are employed including both behavioral scores (FLACC, NIPS), and physiologic pain scoring systems.  Recently in the pain community, there has been movement away from using these self-report scores (which provide only one dimensional transient pain information) towards pain assessments that take into account the effect of pain on a person’s function and abilities.  Shifting the focus of pain assessment toward the patient’s functional capabilities when in pain may provide a more global, chronic picture of the effect of pain in the patient’s life.  These assessments may be more reflective of the various pain modifying factors discussed earlier.  Functional pain scales have been gaining support in the adult literature recently and could be an important development in the assessment of pain in pediatric patients. 

The development of functional pain assessment tools began in the 1980’s when adult pain practitioners wanted to determine how to better assess the impact of low back pain on patient function.  Scoring systems were developed to evaluate a patient’s physical capabilities and limitations in relation to their level of back pain.  These scoring systems include the Sickness Impact Profile (1986), Roland-Morris Questionnaire (1983), Oswestry Disability Index (2000), and the Back Pain Functional Scale (2000).    In a review of the literature in 2010, it was found that twenty-eight functional back pain scoring systems have been developed.   Pain practitioners and orthopedic surgeons use these scales to determine a patient’s level of disability and also as a measurement tool to evaluate function before and after an intervention (such as physical therapy, injections, or surgery) to determine if the intervention is successful.  These scoring systems were further expanded to additional disease-specific assessments, such as scoring systems looking at specific anatomical locations such as the lower extremity or shoulder versus discrete disease entities like rheumatoid arthritis and juvenile rheumatoid arthritis.  

The Functional Pain Scale (FPS) was developed in 2001 as a generic scoring system (as opposed to disease-specific scoring systems) to evaluate the effect of pain on patient function for various different types of pain. The Functional Pain Scale was initially developed to assess pain in older adults, in particular it has been validated and determined to be reliable in the geriatric population.   It is noted that this pain scale, in particular, is useful in patients with limited ability to self-report (geriatric patients) due to its combination of both subjective and objective components used to assess pain.  The Functional Pain Scale has also been revised to create a hospital version, which was recently evaluated in a population of adult chronic pain patients in an acute hospital setting at Massachusetts General Hospital.  It was found that this scale correlated well with pain intensity and the extent to which pain interferes with functioning.  To administer the scale, the patient is first asked if they have pain.  If they cannot answer due to pain, their pain is rated a “10”, the highest score available.  Next, the patient is asked if the pain is tolerable or intolerable (intolerable pain is rated “5” or greater).   Finally, it is determined how the pain interferes with passive vs. active activities, and this further determines the final score.   The application of the Functional Pain Scale to pediatric patients is an attractive idea due to its validity and reliability in patient populations where self-report is difficult.  However, it has not yet been evaluated for validity, sensitivity, or inter-rater reliability in the pediatric population.

A new clinical measurement tool looking at the impact of pain on functioning has been developed at the University of Utah.   This tool is called the Clinically Aligned Pain Assessment (CAPA) Tool.  This pain assessment tool was developed in the adult population as a pilot program in 2012. CAPA takes into account five dimensions of pain (each with scaled responses) including: change in pain (getting better to getting worse), effect of pain on function (can function to cannot function), effect of pain on sleep (normal to awake with pain), comfort level (negligible to intolerable pain), and assessment of pain therapy (effective to ineffective).  No overall scaled score is determined, but this tool rather aims to open discussion about the several dimensions of pain.  The University of Utah reported in 2012 that after implementation of the CAPA tool in certain adult pilot units, their Press Ganey scores around pain management increased from the 45th percentile to the 92nd percentile. Since its creation at the University of Utah, the CAPA pain tool has further been trialed and adopted at other institutions.   Investigators from the University of Minnesota presented their data and experiences with CAPA at the Midwest Pain Society meeting.  They found that there was an improvement in Press Ganey scores, an improvement in patient satisfaction, and a preference by nursing staff to use CAPA over traditional self-report scores.   Of note, this pain assessment tool has not been validated at this time.

In summary, there is growing interest in the use of multi-dimensional functional pain scales to evaluate the impact of pain on a patient’s activities of daily living and physical capabilities.  These scales may take into account a variety of pain modifying factors that are not evaluated with standard one-dimensional self-report scoring systems.   Functional pain scales have been mostly created and studied in the adult population, but may be useful in the pediatric population as well.  The Functional Pain Scale, which was found to be beneficial for patients with difficulties in self-reporting, is an appealing option for the evaluation of chronic pain in pediatric patients.   The CAPA pain assessment tool is a unique, refreshing take on pain evaluation that does not involve providing a scaled score, but instead aims to start a pain dialogue with the provider and patient. Dedicated studies of these functional pain scales in the pediatric population would be an exciting next step.


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