Self-assessment scales are only reliable after age 6 years because they require cognitive and language skills. Between ages 4 and 6 years, the use of several self-reporting pain tools is recommended.1,2,4
Visual analog scale. Self-reporting using the The Visual Analog Scale (VAS) is the gold standard and is the most validated tool. The vertical version is more suitable for children (Figure 1).
The Visual Analog Scale.
Numerical rating scale. The child must know how to count and be able to transcribe the intensity of the pain in numbers to use this scale.
Verbal rating scale. This scale contains a list of adjectives describing different levels of pain intensity rated on a 4-point scale: 0, no pain; 1, mild; 2, moderate; 3, severe. The scales were recently developed for children older than age 8 years.
Faces pain scale. This scale represents faces in 5 levels of pain.16 The absence of standardized representation of painful facial expression is a limit. The faces can represent feelings such as joy, sadness, or anger and not just pain.
Poker chips. Poker-like chips are offered to the child, and the amount of chips taken is proportional to the intensity of the pain. The instruction to the child is “each chip represents a piece (or a piece of pain). Take as many chips as you hurt.”
Drawing. A color system allows for distinguishing 4 levels of pain with their respective locations.
When communication is impossible or the self-report is discordant, the clinician must use a behavioral pain scale.
Behavioral pain scales used in children
Acute pain and procedural pain. The Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) is validated for acute postoperative and procedural pain in children from age 1 to 5 years.17 It is easy to use, fast, reproducible, and has good sensitivity and specificity (Table 1).
EVENDOL is validated in children younger than age 7 years when self-assessment is not reliable, which is an important advantage compared with other tools.7,8
The Faces, Legs, Activity, Cry, and Consolability (FLACC) scale was recently validated in children age 6 months to 5 years with acute pain in different settings with good validity criteria for acute pain in critically ill children18,19 It is easy to use, polyvalent, and reliable but has not been validated in term or preterm newborns.
Postoperative pain. The Child Facial Coding System was inspired by the Neonatal Facial Coding System and uses facial expressions to assess pain in children older than age 18 months and up to age 6 years.20 The combination of these two scales based on facial expressions is interesting because it allows for assessing children from age 0 to 6 years; however, no study has validated this association.
EVENDOL, CHIPPS, and FLACC18 can also be used in the postoperative pain setting.18
The Behavioral Observational Pain Scale was validated in 76 children age 1 to 7 years in a surgical care unit and a neurosurgical postoperative care unit. It is reliable and easy to use.21
The Objective Pain Scale (OPS) was validated for postoperative pain in children age 1 to 13 years.22 It is comprised of physiological items but is not specific. Many use it without blood pressure variation but this has not been validated.
The Toddler Preschooler Postoperative Pain Scale has been validated in children age 1 to 5 years in an immediate postoperative setting and has seven behavioral items.23 The observational time required is >5 minutes.
The Pain Observation Scale for Young Children assesses postoperative pain (otorhinolaryngology surgery) in children age 1 to 4 years.24 It consists of seven behavioral items.
The Postoperative Pain Measure for Parents has 15 items and is used by parents after children return home.25 It is reliable and was initially validated for children age 7 to 12 years. A simplified version with 10 items for children older than age 1 year has been proposed and validated (Table 4).
Prolonged pain. The Gustave-Roussy Child Pain Scale (DEGR) was developed for children age 2 to 6 years with prolonged pain, particularly cancer pain.26 It is reliable for children age 9 months to 10 years. It consists of 10 behavioral and complaint items. In addition to the total score, it has three subscores: direct signs of pain, voluntary expression of pain, and psychomotor atony. The observational time required is more than 4 hours. The Hetero-Assessment of Child Pain (HEDEN) is a shortened version of the DEGR.
Pain in sedated or unconscious children. The COMFORT Behavior Scale is reliable for children from birth to adolescence. The Pasero Opioid-Induced Sedation Scale is used to monitor the state of consciousness and respiratory function of children receiving morphine.27 Depending on these two features, actions are recommended to increase or reduce posology or to dispense naloxone.
Noncommunicating children's pain. The Noncommunicating Children's Pain Checklist (NCCPC) is reliable in children older than age 3 years who cannot communicate verbally because of a cognitive handicap or polyhandicap, regardless of the level of disabilities.28 It includes 30 behavioral items. For a postoperative setting, the scale has three fewer items (concerning sleeping and feeding). The observational time is longer than 10 minutes.
The Pediatric Pain Profile assesses pain in children age 1 to 18 years with severe intellectual disabilities. It can be used by parents and caregivers at home, at school, and in the hospital.29 It has 20 items.
The Revised FLACC (r-FLACC) scale was recently validated for children with cognitive disabilities.30 The FLACC scale was modified by expanding the definition of each item and allowing for adding divergent behaviors specific to the child. It can be completed with or without parental input. Because it is similar to the FLACC, it would likely require less training time.
The Pain Child San Salvador scale involves a retrospective pain assessment (>8 hours). It compares 10 items with the answers to 10 questions from parents, which allows for determining the usual behavior of the child.31
The Individualized Numeric Rating Scale does not have sufficient validity criteria to be recommended.32
Clinical cases. After surgery for hypospadias, a 6-month-old infant has the following behavior: lack of facial expression, no tears, limited movement, no relationship with the mother, tense limbs, eyes closed but sleep is short. All scales show pain (CHIPPS 8/10, Amiel Tison scale 11/20).
Another example is a 5-year-old child in an emergency department setting who cannot move his arm. He complains at the slightest movements of it and during the examination. He answers the questions but has an antalgic posture. He locates the pain to his right arm. At first, self-assessment is necessary. The VAS is 6/10 (pain), and the Faces Pain Scale-Revised is 2/10 (no pain). These results neccessitate the use of behavioral pain scales: EVENDOL (10/15) and FLACC (7/10).
The postoperative period after surgery for acute appendicitis in a 4-year-old child is another situation that requires use of pain measurement. In the postoperative intensive care unit, the child displays these attributes: lightly sleeping, calm, spontaneous and ventilator breathing, quiet breathing, no occasional (≤3) slight movements, restrained muscle tone, less resistance than normal, and normal facial tone. The COMFORT Behavior scale (10/30) shows excess sedation. One hour later, the patient has intermittent complaints, infrequent movements, unusual position, indifference to everything, and tenseness of limbs if mobilization occurs. The COMFORT Behavior scale (16/30) and OPS (2/10) scales underevaluate the pain of a child in distress, but the CHEOPS (8/13), FLACC (5/10), and EVENDOL (7/15) scales do not. After 2 days, a purulent abscess has formed. The child refuses to be touched, complains, has tenseness of body, anxiety, and is inconsolable. All scales are used to assess the pain in the child. The child locates pain to his scar. Self-assessment could be performed with the VAS. Behavioral pain scales could be necessary if there are discordant results or in case of doubt. EVENDOL (13/15), FLACC (8/10), and CHEOPS (9/10) detect the painful sensations.
A 5-year-old child with lymphoma treated with chemotherapy also requires pain assessment. In this case, the child has complaints, loss of enthusiasm, is uncomfortable whatever its position, has restrained movements, and opposition to mobilization. Self-assessment must be performed with VAS or drawing. Self-assessment could be difficult because of loss of enthusiasm and prostration. The DEGR (29/40) and HEDEN (7/10) scales help the caregiver to quote and reassess pain after treatment.