A Systematic Integrative Review of Infant Pain Assessment Tools

Lenora J. Duhn, RN, MSc; Jennifer M. Medves, RN, PhD


Adv Neonatal Care. 2004;4(3) 

In This Article


The search of the 4 databases revealed a total of 35 infant pain assessment tools. Many tools were unidimensional in nature. Additionally, some of the unidimensional tools were specifically designed for research purposes and did not report clinical utility or feasibility. Table 2 outlines the tools in this category. Table 3 and Table 4 outline published and unpublished multidimensional pain assessment tools.

Between 1978 and 2004, 17 unidimensional pain assessment tools were published in the literature;[25,26,27,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48] the most recent was published in 2001. One unpublished tool, the Mills Infant and Toddler Pain Index, which was based on the work of others,[11] was also identified. Only the original studies related to these tools were examined.

As a group these tools tend to focus on infant behavior and movements, and frequently code for specific facial expressions associated with pain. A number of these tools were developed expressly for use in research.[27,32,44,45] The extent of psychometric testing varies by tools (see Table 2 ). Many require extensive training to use and interpret, making clinical utility impractical.

An example of a clinically relevant unidimensional pain tool is the Children's Hospital of Eastern Ontario Pain Scale.[33] It was developed for assessing postoperative pain in young children; the initial study involved children ranging in age from 1 to 7 years. Others have used the tool with infants and children aged 0 to 4 years.[59] The tool assesses 6 elements that include cry (no cry, moaning, crying, scream); facial (composed, grimace, smiling); child verbal (not talking, other complaints, pain complaints, both complaints, positive); torso (neutral, shifting, tense, shivering, upright, restrained); touch (not touching or grabbing at wound, reaching for but not touching wound, gently touching wound area, grabbing at wound, restrained); and legs (neutral, squirming/kicking, drawn up/tensed, standing, restrained). It is a behavioral scale with evidence of interrater reliability and validity.

Current guidelines suggest that the multifaceted nature of pain makes the use of a multidimensional assessment tool, that is, one that combines behavioral, contextual, and physiologic information, preferable to unidimensional options.[13] A brief overview of the existing multidimensional pain assessment tools, and reports of testing, is provided to promote further analyses of existing tools (see Table 3 and Table 4 ).

Four referenced multidimensional tools could not be obtained because they have not been published, or have been published in abstract form only.[11] These scales are the Infant Pain Evaluation Criteria (IPEC); the Wielenga Observation Scale for Pain in Neonates; the Neonatal Pain Assessment Scale; and the Pain Assessment Tool.

The Pain Assessment Inventory for Neonates (PAIN), developed in 1989 and presented at the Florida Conference on Child Health Psychology, was described as a tool to evaluate infants' behavioral and physiologic responses to routine care procedures and acute responses to painful events.[53] Although the authors of the review article cite reliability and validity of this tool,[53] the original document could not be located in our literature search (see Methods).

Another interesting multidimensional tool is the N-PASS: Neonatal Pain, Agitation, and Sedation Scale, which to date has only been published in abstract form.[58] The N-PASS, which controls for differences in gestational age, is designed to evaluate chronic or procedural pain. The assessment criteria include crying or irritability, behavior state, facial expression, extremities/tone, and vital signs (heart rate, respiratory rate, blood pressure, and oxygen saturation). Both pain and/or agitation, as well as level of sedation, are assessed, with levels of sedation noted as negative scores.

In summary, a number of innovative unpublished pain assessment tools are under development. They should be considered works in progress, with ongoing attention to careful psychometric assessment. These tools may have useful clinical applications in the future if and when there is greater evidence of validity, reliability, clinical utility, and feasibility. The focus of the remainder of this review is on published multidimensional assessment tools that have already undergone varying degrees of this testing, and therefore may be more appropriate for clinical application at this time.

Despite publication, several multidimensional assessment tools had limited or no psychometric property testing reported, such as the Pain Assessment Tool (PAT).[49] The PAT assesses posture/tone, sleep pattern, expression, color, cry, respirations, heart rate, oxygen saturations, and blood pressure. It also includes nurses' perceptions of neonatal pain—a variable not seen in other measures. The Neonatal Pain Assessment Tool (or NICU Infant State Assessment Tool as it is also referenced[50]) assesses similar variables such as cry, activity, heart rate, blood pressure, respiratory rate, and oxygen saturations, as well as the infant's state (e.g., relaxed, asleep, or quiet versus awake, fussy, facial grimace with movement), but it too has limited psychometric property testing.

The Scale for Use in Newborns (SUN) was created to improve on the scoring design of a pain assessment tool and has some validity and reliability testing.[51] It assesses similar behavioral and physiologic variables (e.g., central nervous system [CNS] state, breathing, movement, tone, facial expression, heart rate changes, and mean blood pressure changes). The scoring of the SUN compared to 2 other pain tools was completed by one of the authors of the original published study.[51] It is based on this experience that the authors report a preference for this tool because of its ease of use and scale symmetry.

The Comfort Scale is an 8-dimension tool that was developed for pediatric intensive care patients (newborn to 24 months).[53] The dimensions are alertness, calmness/agitation, respiratory response, physical movement, mean arterial pressure, heart rate, muscle tone, and facial expression. Although its reliability and validity are acceptable, it has been reported as more difficult to use when compared to other scales, such as the NIPS and SUN.[51]

The Pain and Discomfort Scale,[56] referenced as the Objective Pain Scale (OPS[54]), is a multidimensional tool that assesses both physiological and behavioral indicators, specifically blood pressure, crying, movement, agitation, posture, and complaints of pain (where appropriate by age). It was initially studied with children 18 months to 12 years of age. Although the stated use of the tool is for older, preverbal children,[54] it has been used in studies with infants,[60] likely because of its simplicity and ease of use. Reporting of validity and reliability appears limited.

The Modified Infant Pain Scale (MIPS) is a multidimensional pain assessment tool[57] that builds on the unidimensional scale, the Clinical Scoring System.[38] It has 13 dimensions that include sleep, facial expression, quality of cry, spontaneous motor activity, excitability and responsiveness to stimulation, flexion of fingers and toes, suckling, overall tone, consolability, sociability, and physiologic changes in heart rate, blood pressure, and saturation. Each dimension is scored 0 to 2, and a higher score is an indication of less pain. During analysis, the MIPS was divided into partial scores (P-MIPS), which excluded data on sleep and vital signs, and total scores (T-MIPS). Infants were categorized as comfortable with scores on the P-MIPS >12 and scores on the T-MIPS >20. The authors report initial criterion validity and interrater reliability, with recommendation for use of the P-MIPS for a clinical 2-point pain assessment.[57]

The Distress Scale for Ventilated Newborn Infants (DSVNI), primarily designed to assess infants' reaction to invasive procedures, is the first of its kind to focus specifically on ventilated newborn infants.[52] Although it requires further testing of validity, as well as reliability and clinical utility, it was developed for use in routine clinical practice and, for that reason, its ease of application may be of benefit.

The CRIES is a multidimensional assessment tool that focuses on postoperative pain in infants.[54] The CRIES assesses crying, oxygen requirement to maintain a saturation >95%, increased blood pressure and heart rate, expression, and sleep state. Validity and reliability have been tested in infants of ≥32 weeks gestation. The fact that the tool is in the form of an acronym and its ease of use make the tool appealing.

The NIPS is also a multidimensional assessment tool for determining procedural pain and requires assessment of facial expression, cry, breathing patterns, arm movement, leg movement, and state of arousal.[24] The NIPS has limited reporting of clinical utility despite its psychometric property testing.

The Pain Assessment in Neonates (PAIN) tool was developed by combining dimensions of the NIPS and the CRIES.[55] The 7 dimensions are facial expression, cry, breathing pattern, extremity movement, state of arousal, oxygen required to maintain a saturation >95%, and increased vital signs, specifically heart rate from baseline. Individual dimensions are scored from 0 to 2. A total score is calculated ranging from 0 to 10, with a higher score indicating increased pain. Despite initial positive reports of construct and criterion validity testing (although the high correlation may be overestimated given it was tested against the NIPS), there was no indication of reliability.[55]

The PIPP is a multidimensional composite pain tool.[22] In terms of psychometric property testing, there has been more validity and reliability testing of the PIPP than any other measure of pain in infants.[8] Numerous studies have used the PIPP to assess infant pain.[61,62,63,64,65,66,67,68,69] The measure was developed to assess acute pain in preterm and term infants in both research and clinical practice. The dimensions are behavioral, physiological, and contextual in nature. They include gestational age, behavioral state, heart rate, oxygen saturation, brow bulge, eye squeeze, and nasolabial furrow. The behavioral indicators were derived from the Neonatal Facial Coding System (NFCS).[27,28]

In a previous study, a convenience sample of 124 preterm infants was observed, wherein increases in heart rate and decreases in oxygen saturation were noted with an invasive procedure.[70] The physiologic indicators that were included in the PIPP were chosen based on their reported consistency.[68] Each indicator is evaluated on a 4-point scale consisting of 0, 1, 2, and 3. A total score of 6 or less generally indicates minimal or no pain, whereas scores of greater than 12 indicate moderate to severe pain.[8] The PIPP has instructions for use and training at the bedside and takes approximately 1 minute to review, plus 2 to 3 minutes of practice.[8]


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