The measurement of pain in infants, children, and adolescents: from policy to practice.

Pain and Policy

Pain has received substantial policy attention in the past decade at national and international levels. Policy is defined as "principles that govern actions and can refer to laws, decisions, options, projects, programs, or other terms for alternatives." (34)(p viii) Pain-related policy includes laws (ie, legally binding rules of conduct issued by governments based on constitutional, legislative, or regulatory decisions) as well as guidelines that are not legally binding. (35) Guidelines also are called policy or position statements and are developed by government agencies and professional associations to articulate positions on specific issues. (35) Clinical practice guidelines are "systematically defined statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances." (36)(p38)

The discussion of policy in this update will be limited to pain-related clinical practice guidelines and policy statements that have been issued in the past decade. These documents are applicable to health care providers across disciplines and help define standards of practice and expectations for professional actions. (35) Some guidelines apply to people of all ages, whereas others focus specifically on the identification and management of pain in infants, children, and adolescents.

Acute pain was the subject of 2 important clinical practice guidelines published in 1992. In the United States, the Agency for Health Care Policy and Research (AHCPR) published the clinical practice guideline Acute Pain Management: Operative or Medical Procedures and Trauma. (22) Concurrently, the IASP published Management of Acute Pain: A Practical Guide. (28) Both publications addressed acute pain across the life span and included specific chapters on management of postoperative and procedural pain in infants, children, and adolescents. The AHCPR publication also was accompanied by the quick reference guide Acute Pain Management in Infants, Children, and Adolescents: Operative and Medical Procedures. (37) The guidelines identified gaps between pain research and clinical practice, provided physiological reasons for aggressive management of acute pain, and recommended specific assessment and management strategies.

The importance of pain identification and management to the quality of health care and health outcomes was further underscored in 1994 and 1995 with the publication of several clinical guidelines related to management of cancer pain. Management of Cancer Pain (38) was published by the AHCPR in 1994, and the Quality of Care Committee of the American Pain Society (APS) issued Quality Improvement Guidelines for the Treatment of Acute Pain and Cancer (39) the following year. The AHCPR included pediatric cancer pain guidelines as part of Management of Cancer Pain, (40) which was published in 1994. Internationally, the World Health Organization (WHO) issued the second edition of Cancer Pain Relief (41) in 1996 and published Cancer Pain Relief and Palliative Care in Children (42) in collaboration with the IASP in 1998. Although clinical guidelines published by the former AHCPR (now the Agency for Health Care Research and Quality) between 1992 and 1996 are now considered outdated because of advances in knowledge and changes in intervention,as they are included in this discussion to demonstrate the evolution of policy in this topic area.

In the middle to late 1990s, a number of organizations issued policy statements asserting that patients had the right to good pain assessment and management. In 1995, an APS policy statement coined the phrase "pain: the fifth vital sign," advocating for pain assessment along with the examination of other vital signs (ie, time pulse, blood pressure, respiration rate, and temperature) for patients of all ages. (44) Similarly, the pain relief position statement approved in 1997 by the Executive of the Canadian Pain Society (CPS) affirmed the right of all patients to pain relief and emphasized the responsibilities of health care professionals to identify and manage pain. (45)

Several policy statements and clinical practice guidelines have been published in the last 3 years that emphasize the need for improved identification and management of pain in infants, children, and adolescents. In 2000, the American Academy of Pediatrics (AAP), in conjunction with the Canadian Paediatric Society, addressed the subject of pain management in newborn and premature infants in the policy statement Prevention and Management of Pain and Stress in the Neonate. (46) During the same year, the APS published the position statement Pediatric Chronic Pain. (47) A collaborative effort between the AAP and the APS resulted in the 2001 publication of a policy statement The Assessment and Management of Acute Pain in Infants, Children, and Adolescents. (48) The APS published 2 disease-specific clinical practice guidelines that target pain in children and adults--Guideline for the Management of Acute and Chronic Pain in Sickle-Cell Disease (49) and Guideline for the Management of Pain in Osteoarthritis, Rheumatoid Arthritis, and Juvenile Chronic Arthritis (50)--in 1999 and 2002, respectively.

On January 1, 2001, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) implemented a sweeping policy initiative mandating pain assessment and management in accredited health care organizations. This initiative began as a 2-year collaborative project between JCAHO and the University of Wisconsin Medical School, with funding from the Robert Wood Johnson Foundation, and culminated in the development of 6 Pain Management Standards that were subsequently endorsed by the APS. The first standard affirms the right of every patient to appropriate pain assessment and management. Other standards address expectations related to pain policies and procedures, documentation of pain assessment and management across clinical settings, and the education of patients and their families about pain. (1) With the exception of laboratories, the Pain Management Standards now apply to all departments and services in JCAHO-accredited health care organizations, including physical therapy.

In summary, national and international organizations have developed clinical practice guidelines and policy statements to improve the identification and management of pain in all patients. These documents provide a succinct synthesis of relevant literature, recommend guidelines for practice, and identify specific expectations for professionals who work with people who have, or are at risk for, pain. Pediatric pain policy statements identify factors that contribute to inadequate recognition and management of pain, and they recommend strategies to improve clinical practice. Physical therapists and other health care providers are expected to examine and evaluate pain in infants, children, and adolescents in a developmentally appropriate manner using the best tests and measures available.

Measurement of Pediatric Pain

Valid and reliable measurements of pain are needed to identify patients who require intervention and to evaluate the effectiveness of intervention. The terms "measurement" and "assessment" are widely used in the pain literature and differentiated in the following manner. Measurement refers to the assignment of a number or value and is commonly associated with the dimension of pain intensity. Assessment describes a more complex process in which information about pain, its meaning, and its effect on the person is considered along with quantitative values. (51,52) In physical therapist practice, the patient history, systems review, and use of tests and measures are the 3 components of the examination. (31) The term evaluation in physical therapy is analogous to assessment and describes the process of synthesizing information gathered during the examination to establish a diagnosis, prognosis, and plan of care.

The examination and evaluation of pain are central to the profession of physical therapy. Pain is 1 of the 24 categories of tests and measures administered during an initial examination. In addition, the (guide to Physical Therapist Practice (31) recommends the examination of pain intensity, quality, temporal and physical characteristics, reflecting the complex and multidimensional nature of this phenomenon. Although the principles of pain examination and evaluation apply across the life span, infants and children present some unique challenges that require consideration of the child's age, developmental level, cognitive and communication skills, previous pain experience, and associated beliefs and fears.

Pain measures are classified as self-report, behavioral, or physiological measures. The methodological framework of Kirshner and Guyatt (53) categorizes health measures according to 3 broad purposes. Discriminative measures differentiate among people based on some attribute (eg, identify those with and without pain). Evaluative measures detect and quantify the magnitude of change in a specific attribute over time for a person or for a group. Predictive measures categorize individuals based on prognosis for a test result, condition, or function in the future. (53) Most pain measures are used to identify people in pain (discriminative) or to detect and measure changes in pain over time (evaluative). Evaluative pain measures should demonstrate the property of responsiveness, or the ability to detect clinically meaningful changes in pain, whereas discriminative measures should be sensitive and specific in identifying pain.

A plethora of pediatric pain measures that provide valid and reliable measurements have been developed for clinical and research purposes, and the literature describing their use is expanding rapidly. In-depth information is available in the form of review articles, (54-56) book chapters, (52,57) and books. (58-60) Eighteen measures were reviewed for this update, and relevant information from peer-reviewed, primary sources is summarized and presented in the Table. (61-115) The psychometric proper ties of the measures were evaluated using criteria described by Law et al. (116)

Self-Report Measures

Self-report measures are considered the "gold standard," and the most valid approach to pain measurement. It is important to note that, although self-report measures exist in verbal and nonverbal formats, both require sufficient cognitive and language development to understand the task and generate an accurate response. (52,57) Verbal self-report measures include structured interviews, questionnaires, self-rating scales, and pain adjective descriptors. Nonverbal measures include facial expression scales, visual analog scales (VASs), and drawings. (52,57) The ability of children to report and to describe pain emerges with increasing age and experience and typically follows a developmental progression, although there is always considerable variation associated with individual differences. (57,117) Most 2-year-old children can report the presence and location of pain, but they do not develop the cognitive skills needed to describe pain intensity until about 3 or 4 years of age. As a rule of thumb, most 3-year-old children can use a 3-level pain intensity scale with simple terms such as "no pain," "a little pain," or "a lot of pain." Four-year-old children can usually manage 4- or 5-item scales. (61,62,118,119) Before using even simple pain intensity scales, however, clinicians should determine a child's understanding of basic concepts such as quantification, classification, and matching. (118) Self-report measures are not limited to the dimension of pain intensity. Measures of pain affect (emotional reactions), provide information about general distress, unpleasantness, mood, and anxiety associated with pain. A child's ability to rate pain affect emerges later than pain intensity, and these measures are usually introduced when children are 5 years of age or older. (63-65) When children are approximately 8 years of age, they are able to rate the quality of pain. (57,66)

Facial expression scales are often used with young children to obtain a self-report of pain. The 5 facial expression scales listed in the Table have some features in common. All consist of a series of faces with varying expressions that range from neutral or smiling to distress or crying. The response requirement for young children is to point to the face that corresponds most closely to how much pain they have (intensity) (61,67,68) how the pain makes them feel (affect), (63) or both. (69) Facial expression scales are easy to administer, and most of them demonstrate adequate to excellent psychometric properties. The Hester Poker Chip Tool is another measure of pain intensity that is recommended for use with preschoolers. (70,71) Four red poker chips represent "pieces of hurt," and children are asked to select how many "pieces of hurt" they have. The psychometric properties of this self-report measure are well established.

An expanded list of self-report pain measures is available to use with school-aged children. Quantitative scales--such as VAS, (118) the Coloured Analogue Scale (CAS), (72) and numerical scales--require more complex representational concepts and skills that generally emerge between 5 and 7 years of age. The Adolescent Pediatric Pain Tool (66,73) and the Pediatric Pain Questionnaire (74,120) are examples of multidimensional pain measures used with older children and adolescents. The McGill Pain Questionnaire (MPQ) (75,76) is an example of an adult pain measure that has been used in clinical practice with older adolescents. In summary, there are many excellent pediatric self-report measures, and their clinical application requires careful consideration of age, developmental, and measurement issues.

Behavioral Measures

For infants, very young children, and children with severe cognitive or communication impairments, it may be impossible to use self-report measures; therefore, behavioral measures are required. Behavioral measures include measures of crying, facial expression, body posture and movements, daily routines, or some combination of these items. The interpretation of crying, particularly in infants, is often challenging because this behavior represents general distress rather than pain-specific behavior. Furthermore, infants and children who are very ill or medically fragile are less equipped to mount a vigorous cry in response to pain than their more robust peers who are not very ill or medically fragile. In contrast, measures that involve the detailed coding of infant facial expressions, body postures, and movements have proved to be excellent behavioral measures of pain.

The Neonatal Facial Coding System (NFCS) and the Child Facial Coding System (CFCS) are behavioral measures of pain intensity. (77,78,121,122) The NFCS records 9 different facial movements (eg, brow bulge, eye squeeze, nasolabial furrow, mouth position, chin quiver) on videotape for later coding and scoring. It provides sensitive, reliable, and valid measurements of short-term acute pain in both preterm and full-term neonates. (77,78,123) Derived from the NFCS, the CFCS involves the coding of 13 facial actions and provides valid and reliable measurements of pain intensity in young children. (79)

Some behavioral measures involve the observation and interpretation of body postures and movements. The Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) measures acute postoperative pain in children aged 1 to 7 years. The CHEOPS uses 6 behaviors (crying, facial expression, verbal expression, torso movement, touching wound, and leg movements) to indicate pain. (80) This measure is widely used and demonstrates excellent psychometric properties for measuring sharp, short-duration pain. The FLACC (Face, Legs, Activity, Cry, and Consolability) Behavioral Pain Assessment Scale was developed more recently to quantify' pain behaviors in young children during the postoperative period. (81) The FLACC measures pain intensity and can be used with children who range in age from 2 months to 7 years. Recent studies (31-33) show adequate psychometric properties.

The identification and measurement of pain in children with severe cognitive, communication, and motor impairments are particularly challenging. (124-126) Communication and cognitive impairments may limit or preclude the use of self-report measures. Moreover, detailed coding of facial expressions and body movements may be problematic for children with atypical motor development because of muscle weakness, paralysis, contractures, abnormal postures, and involuntary movements. Fortunately, pain in this population of children has received greater attention in recent years and has resulted in some very encouraging new developments. (13,124,127,128) Several research groups have developed, or are in the process of developing, methods to measure pain in this population. (84,124,125,127-132) The Non-communicating Children's Pain Checklist (NCCPC) is an example. (84,85,124) The NCCPC was initially validated for use by family members and caregivers of children with severe disabilities in the home setting. A postoperative version of the checklist, the NCCPC-PV, was developed for health care providers to use in hospital settings. Breau et al (36) found that the NCCPC-PV was effective in detecting postoperative pain in children with severe cognitive and communication impairments. The NCCPC was recently revised following research that involved a larger group of children and their caregivers, and the psychometric properties of this revised version (NCCPC-R) are excellent. (87) In summary, a behavioral approach to measuring pain is essential for infants, very young children, and children with severe cognitive or communication impairments, and many good behavioral measures have been developed for clinical use.

Physiological Measures

Physiological or biological measures constitute the third category of pain measures. Studies of physiological responses to pain in infants and children often include heart rate, vagal tone (parasympathetic inhibitory influence on the heart), blood pressure, respiration rate, oxygen saturation rate, and palmar sweating. (133) Neuroendocrine responses (eg, catecholamine, corticosteroid, growth hormone, glucagon, and cortisol levels) to painful events also have been studied. (134) Reviews of research evidence demonstrate several challenges associated with interpreting physiological responses to painful events. (52,133) First, pain is a stressor, and physiological responses to various types of stress are similar and not unique or specific to noxious stimuli. Second, these measures have been used to study responses to short-duration, sharp pain, and physiological responses to long-term pain appear to habituate. Finally, the general health and maturational age of the infant or child also may influence physiological responses to pain. Consequently, physiological indicators of pain are used in conjunction with other measures.

Composite Measures

Pain measures that use some combination of physiological, behavioral, or self-report variables are termed composite measures. (135) This combined approach is often used to measure pain in infants and in children who are medically fragile. Infant measures also may include information about gestational age and general behavioral state. The Premature Infant Pain Profile (PIPP) (88) and the Neonatal Infant Pain Scale (NIPS) (89) are examples of composite scales used to evaluate pain in premature and full-term infants. The PIPP uses gestational age, behavioral state, 2 physiological indicators, and 3 facial expression indicators to quantify pain. (88) The NIPS includes 5 behavioral indicators (ie, facial expression, cry, arms, legs, and state of arousal) and 1 physiological indicator (ie, breathing patterns) of pain. (89) Other composite measures may be used for older children.

Conclusion

In summary, numerous clinical practice guidelines and policy statements have been published in the last 10 years on the subject of pediatric pain. These publications are valuable resources for physical therapists and other health care providers who serve infants, children, and adolescents who have, or are at risk for, pain resulting from diverse etiologies. Improved management is contingent on valid and reliable measurement of pain. Fortunately, there are many excellent pediatric pain measures. Selection of appropriate measures requires an understanding of pain, measurement, and child development. The measurement of pain in infants, young children, and children with developmental disabilities who are unable to self-report is particularly challenging and merits increased attention. Physical therapists are well positioned to support and implement policy initiatives to improve the identification and management of pediatric pain and to contribute new knowledge through research.

Table.
Selected Pediatric Pain Measures

                       Intended                      Dimension
Name of Measure        Age Group     Type of Pain    Measured

Adolescent Pediatric   8-17 y        Acute           Pain location,
  Pain Tool (APPT)                                     intensity,
  (66,73,90,91)                                        and quality

Child Facial Coding    1-6 y         Acute           Pain intensity
  System (CFCS)
  (79,92,93)

Children's Hospital    1-7 y         Acute           Pain intensity
  of Eastern Ontario
  Pain Scale
  (CHEOPS)
  (80,94-97)

Coloured Analogue      5 y and       Acute,          Pain intensity
  Scale (CAS)            older         recurrent,
  (72,98,99)                           and chronic

Faces Pain Rating      3 y and       Acute           Pain intensity
  Scale (69,95)          older                         and affect

Faces Pain Scale       4 y and       Acute           Pain intensity
  (FPS)                  older
  (62,68,98-101)

Faces Pain Scale-      4 y and       Acute           Pain intensity
  Revised (FPS-R)        older
  (61)

Facial Affective       5 y and       Acute,          Pain affect
  Scale (FAS)            older         recurrent,
  (63-65)                              and chronic

FLACC (Face, Legs,     Infancy       Acute           Pain intensity
  Activity, Cry, and     to 7 y
  Consolability)
  Behavioral Pain
  Assessment Scale
  (81-83)

Hester Poker Chip      4-7 y         Acute           Pain intensity
  Tool
  (65,70,71,102,103)

McGill Pain            12 y and      Acute,          Pain location,
  Questionnaire          older         recurrent,      intensity,
  (75,76,104)                          and chronic     and quality

Neonatal Facial        Preterm and   Acute           Pain intensity
  Coding System          full-term
  (NFCS)                 infants
  (77,78,105,106)

Neonatal Infant Pain   Preterm and   Acute           Pain intensity
  Scale (NIPS)           full-term
  (89,107)               infants

Non-communicating      3-19 y        Acute           Pain intensity
  Children's Pain
  Checklist (NCCPC),
  (84-85)
  postoperative
  version
  (NCCPC-PV), (86)
  revised version
  (NCCPC-R) (87)

Oucher Scale           3 y and       Acute           Pain intensity
  (67,108-110)           older

Pediatric Pain         8 y and       Chronic         Pain intensity,
  Questionnaire          older                         affect, and
  (PPQ) (74,111)                                       quality

Premature Infant       Premature     Acute           Pain intensity
  Pain Profile           infants
  (PIPP)
  (88,112,113)

Visual analog scale    5 y and       Acute,          Pain intensity
  (VAS) (63,114,115)     older         recurrent,
                                       and chronic

                       Type of                         Psychometric
Name of Measure        Measure       Administered By   Properties (a)

Adolescent Pediatric   Self-report   Parents and       Reliability:
  Pain Tool (APPT)                     health care       excellent
  (66,73,90,91)                        professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         adequate

Child Facial Coding    Behavioral    Health care       Reliability:
  System (CFCS)                        professionals     adequate
  (79,92,93)                                           Validity:
                                                         adequate
                                                       Responsiveness:
                                                         adequate

Children's Hospital    Behavioral    Health care       Reliability:
  of Eastern Ontario                   professionals     excellent
  Pain Scale                                           Validity:
  (CHEOPS)                                               excellent
  (80,94-97)                                           Responsiveness:
                                                         excellent

Coloured Analogue      Self-report   Parents and       Reliability:
  Scale (CAS)                          health care       excellent
  (72,98,99)                           professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         adequate

Faces Pain Rating      Self-report   Parents and       Reliability:
  Scale (69,95)                        health care       adequate
                                       professionals   Validity:
                                                         adequate
                                                       Responsiveness:
                                                         poor

Faces Pain Scale       Self-report   Parents and       Reliability:
  (FPS)                                health care       excellent
  (62,68,98-101)                       professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         excellent

Faces Pain Scale-      Self-report   Parents and       Reliability:
  Revised (FPS-R)                      health care       excellent
  (61)                                 professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         adequate

Facial Affective       Self-report   Parents and       Reliability:
  Scale (FAS)                          health care       excellent
  (63-65)                              professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         adequate

FLACC (Face, Legs,     Behavioral    Health care       Reliability:
  Activity, Cry, and                   professionals     excellent
  Consolability)                                       Validity:
  Behavioral Pain                                        excellent
  Assessment Scale                                     Responsiveness:
  (81-83)                                                adequate

Hester Poker Chip      Self-report   Parents and       Reliability:
  Tool                                 health care       excellent
  (65,70,71,102,103)                   professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         adequate

McGill Pain            Self-report   Parents and       Reliability:
  Questionnaire                        health care       excellent
  (75,76,104)                          professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         excellent

Neonatal Facial        Behavioral    Health care       Reliability:
  Coding System                        professionals     excellent
  (NFCS)                                               Validity:
  (77,78,105,106)                                        excellent
                                                       Responsiveness:
                                                         excellent

Neonatal Infant Pain   Composite     Health care       Reliability:
  Scale (NIPS)                         professionals     adequate
  (89,107)                                             Validity:
                                                         adequate
                                                       Responsiveness:
                                                         adequate

Non-communicating      Behavioral    Parents,          Reliability:
  Children's Pain                      caregivers,       excellent
  Checklist (NCCPC),                   and health      Validity:
  (84-85)                              care              excellent
  postoperative                        professionals   Sensitivity/
  version                                                specificity:
  (NCCPC-PV), (86)                                       excellent
  revised version
  (NCCPC-R) (87)

Oucher Scale           Self-report   Parents and       Reliability:
  (67,108-110)                         health care       excellent
                                       professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         excellent

Pediatric Pain         Self-report   Parents and       Reliability:
  Questionnaire                        health care       excellent
  (PPQ) (74,111)                       professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         adequate

Premature Infant       Composite     Health care       Reliability:
  Pain Profile                         professionals     excellent
  (PIPP)                                               Validity:
  (88,112,113)                                           excellent
                                                       Responsiveness:
                                                         adequate

Visual analog scale    Self-report   Parents and       Reliability:
  (VAS) (63,114,115)                   health care       excellent
                                       professionals   Validity:
                                                         excellent
                                                       Responsiveness:
                                                         excellent

(a) Psychometric properties rated using criteria described by Law et
al. (116) Excellent=more than 2 well-designed and supportive studies,
adequate=1 or 2 well-designed and supportive studies, poor=studies
unavailable or poorly designed, or nonsupportive studies.

The author thanks Dr Susan R Harris for her thoughtful comments and review of the manuscript before submission.

This update was completed in partial fulfillment of the requirements for Dr O'Rourke's Doctor of Philosophy degree in psychology at the University of Vermont.

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D O'Rourke, PT, PhD, is Assistant Professor, Department of Physical Therapy, College of Nursing and Health Sciences, University of Vermont, Burlington, VT 05405 (USA) ([e-mail]).