Reliability and validity of the faces and word descriptor scales to measure procedural pain

Reliability and Validity of the Faces and Word Descriptor Scales to Measure Procedural Pain Juanita Fogel Keck, DNS, RN Janis E. Gerkensmeyer, MSN, RN, CS Betsy A. Joyce, EdD, RN, PNP Julia G. Schade, DNS, RN Reliability and validity of the Faces and Word Descriptor Scales to measure pain in verbal children undergoing painful procedures were assessed. Test-retest reliability and construct and discriminant validity were supported for both instruments among a sample of 118 children in three age groups (3-7, 8-12, 13-18). Construct validity was determined by comparisons with a visual analogue scale and a numerical scale with known validity. A majority of the children preferred to use the Faces scale when providing self-report of pain regardless of age. The Faces and Word Descriptor Scales are valid and reliable instruments to measure procedural pain intensity. Copyright 9 t996 by W.B. Saunders Company

T IS WELL DOCUMENTED that children

I in the past have received inadequate interventions for pain (Beyer, DeGood, Ashley, & Russell, 1983; Burokas, 1985; Eland & Anderson, 1977; Mather & Mackie, 1983; Perry & Heidrich, 1982; Schecter, Allen & Hanson, 1986). Nurses at a large Midwestern pediatric hospital confirmed that undertreatment of children's pain continued to occur in their setting. A Pediatric Pain Specialized Practice Group (PPSPG), composed of experienced nurse representatives from across the hospital was formed to address pain management issues in the hospital. They implemented standards of pain care which had been developed in the interest of improving pain relief among their patients. Concerns regarding undertreatment of pain persisted and a subsequent quality assurance initiative found that evaluation of pain relief was severely hampered by lack of systematic documentation of pain relief. A review of the literature suggested that a pain management flow sheet to facilitate documentation of the child's pain experience should improve pain

From the Indiana University School of Nursing and Indiana University Medical Center, Indianapolis, IN. Address reprint requests to Juanita Fogel Keck, 1111 Middle Drive, 317-B, Indianapolis, IN 46202. Copyright 9 1996 by W..B. Saunders Company 0882-5963/96/1106-000553. 00/0 368

management for these children. The effectiveness of a flow sheet to improve pain management has been suggested by Ellis (1988), McCaffery and Beebe (1989), and Meinhart and McCaffery (1983). Empirical support for the effectiveness of a flow sheet in improving pain management in pediatric settings has been provided by Stevens (1990). Based on the literature, the nurses decided to develop a pediatric pain flow sheet that would facilitate assessment and documentation of pain and pain relief for children. Before a flow sheet can be credible, valid and reliable tools to measure pain are needed. The nurses in the PPSPG identified additional criteria for assessment tools to be used in their clinical settings. They desired tools that were acceptable to both patients and nurses and usable among children in various stages of cognitive development. They also needed costeffective tools which were easy to administer and score while providing low patient and nurse burden. Self-reports of pain have provided the most reliable data from adults (Huskisson, 1974; Jacox, 1979, Agency for Health Care Policy and Research [AHCPR] 1992). Because children differ from adults in cognitive ability depending on developmental level, concerns about validity of self-report of pain among children have been expressed (Abu-Saad, 1984; Aradine, Beyer & Journal of Pediatric Nursing, Vol 11, No 6 (December), 1996

RELIABILITYAND VALIDITYOF PAIN SCALES

Tompkins, 1988; Beyer & Aradine, 1986; Bieri, Reeve, Champion, Addicoar & Ziegler, 1990; Maunuksela, Olkkola & Korpella, 1987). Empirical support that self-report measures are valid and reliable indicators of pain among verbal children has been provided by Aradine, et al. (1988), Beyer and Aradine (1986, 1987, 1988), Maunuksela, et al. (1987), and McGrath, de Veber and Hern (1985). Clinical practice guidelines for management of acute pain concluded that self-report was the most valuable indicator of pain for both adults and verbal children (AHCPR, 1992). Through a review of the literature, the members of the PPSPG identified two general categories of pain assessment tools, visual analoguetype scales (VAS) and pictorial or manipulative instruments for use on the proposed pain management flow sheet. The PPSPG nurses wanted to give children a choice of scales to use, one pictorial and one a VAS-type, to allow for individual patient preference. Pictorial or manipulative scales considered included the Oucher (Beyer, 1984), the Eland Color Scale (Eland and Anderson, 1977), the Poker Chip Tool (Hester, 1979) and the Faces Scale (Wong & Baker, 1988). The Oucher is available in three forms each composed of photographs of male children from three ethnic groups in various stages of pain. The original instrument depicting a White boy has considerable psychometric support (Aradine et al., 1988; Beyer & Aradine, 1986, 1987, 1988). In addition to reliability and validity support, the Oucher incorporates both a pictorial and VAS-type scale (a numerical scale represented in a vertical line). The Oucher was not considered for use in the hospital because it introduced considerable nurse burden. It was large (approximately 24 inches square) and needed to be carried from bedside to bedside. The nurses were concerned that its size would render it difficult to administer. In addition, its cost rendered it financially unfeasible as multiple copies would be needed. The Eland Color Scale required the child to select crayons in colors that represented varying levels of pain for them. They then were to use the selected crayons to draw on predrawn body outlines where they hurt, selecting the color that represented the pain intensity experienced at that location. Children have shown ability to indicate various intensities of pain at various body locations using this technique. The nurses

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in the PPSPG believed this technique to be quite useful in aiding children to identify pain intensity and location; however, they believed it would have both high nurse and patient burden. Nurses would have to carry the sheets of paper with body drawings and enough crayons of different colors to provide individual children with their color choices for each assessment. The children would have to be able to assume a body position that would allow them to color the body outlines. The nurses were concerned that many children would be able to respond to the instrument with great difficulty, either because of their pathology or their pain level. The Poker Chip Tool was not considered because it requires that nurses carry 4 poker chips with them at all times contributing more nurse burden than the nurses were willing to accept. In addition, the nurses were concerned that considerable patient burden would ensue as children assumed a body position which would enable them to select poker chips. Concerns about infectious diseases rendered the nurses unwilling to use the same poker chips for pain assessment among subsequent children. The Faces tool developed by Wong and Baker (1988) was preferred by the nurses in the PPSPG (Figure 1). The tool consists of six black and white stylized cartoon faces representing various degrees of pain. The cartoons represent actual drawings rendered by children who were asked to draw what they would look like if they had each level of pain (Wong, December 1993 personal communication). The space needed to present the Faces tool is small (llA inches high by 7 inches wide) allowing it to be easily incorporated on a flow sheet that would fit in a patient's chart and bedside documentation system. It is inexpensive because it can easily be duplicated on the back of the pain management flow sheet. Because it can be reproduced for each child's bedside, spread of infections is not an issue. The tool is not burdensome to either child or nurse. Children are asked to either point to or identify by number, the face that best represents how much they hurt thereby making it easy for the child to indicate pain intensity and easy for the nurse to administer and score. Visual analogue-type scales included (1) a 100 mm line, either horizontal or vertical, bounded by "no pain" and "worst pain" at the extremes, (2) word graphic scales in which five or six word descriptors of amount of pain are placed at equidistant points along the line, and

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(3) numerical rating scales in which numbers range from 0 to 10 at equidistant points. Visual analogue-type scales using word descriptors have been shown to be valid and reliable means to measure pain among children 5 years of age and older (McGrath, de Veher & Hearn, 1985), 8 years and older (Tesler, et al., 1991), children as young as 18 months to 18 years (Maunuksela, et al., 1987), and children from ages 3 to 18 years (Wong & Baker, 1988). The VAS-type word graphic scale reported by Tesler et al. (1991) has considerable psychometric support and has been supported by the U.S. Department of Health and Human Services (AHCPR, 1992) to measure pain in children. The scale incorporates five word descriptors placed equidistant along a 100 mm line. Patients are to bisect the line at the point they believe represents the amount of their pain. It is assumed that the children will place a mark anywhere along the line, not just at the point of location of the word descriptors. Scores are determined by measuring the distance between the left end of the scale and the point of the bisect in millimeters. The scale is easily reproduced and can be incorporated into usual bedside assessment systems. Although valid and reliable, the scale was not considered by the nurses as a viable assessment tool for the flow sheet because it involves considerable patient and nurse burden. The child must be able to assume a body position that allows for the manual manipulation of a pencil. The nurse must carry a millimeter ruler and measure the line each time pain is assessed. Consistent, accurate measurement with this tool was also a concern. Reliability and validity of numerical scales have also been supported (Aradine, Beyer & Tompkins, 1988; Beyer & Aradine, 1986, 1987, 1988; Maunuksela, et al., 1987). The scales are easily reproduced and easy for both nurses and children to use. However, the pain intensity scores obtained for most numerical scales would differ greatly from those obtained using the Faces scale. The range of scores possible using Faces is 0 to 5. Scores range from 0 to 10 using most numerical scales. A rating of 5 on one scale would indicate a very different level of pain than a rating of 5 on the other. The nurses wanted the numbers obtained from the pictorial and VAS-type scales to be comparable to allow for ease of evaluation of the pattern of a child's

KECK fiT AL

pain experience on the pain management flow sheet. The Word Descriptor Scale as described in Whaley and Wong (1987) was the preferred VAS-type scale. The scale consists of six words used to describe pain from "no pain" to "worst pain" (Figure 1). Each word is accompanied by a number for use in scoring. The numbers appear to correspond to the numbers associated with the individual faces on the Faces scale. The original Word Descriptor Scale was modified for use in this study. The words used on the original scale to indicate mild and moderate pain have been identified as problematic for use among young children (Tesler, et al., 1991). Therefore, the Word Descriptor Scale was modified using the words incorporated on the Word Graphic Scale reported by Tesler, et al. (1991). The word "mild" was changed to "little" and "moderate" was changed to "medium." Although the Faces and Word Graphic Scales had some psychometric support (Wong & Baker, 1988), validity and reliability data were insufficient to support the use of the scale without further testing.

PURPOSE The purpose of the study was to investigate the Faces and the modified Word Descriptor Scale for concurrent validity, discriminant validity, and test-retest reliability. An indirect measure of internal consistency reliability was also assessed. The Word Graphic Scale reported by Tesler et al. (1991) and a numerical rating scale, both with reliability and validity support were used to assess concurrent validity (Figure 1). A second purpose was to determine which of the four instruments were preferred by the children.

SAMPLE Data collection took place at a large, Midwestern pediatric hospital associated with a large University Medical Center. The target population was all children with hemotology and oncology diagnoses between the ages of 3 and 18 years who were undergoing painful procedures. Because of a paucity of children who met the study inclusion criteria, the target population was expanded to include children experiencing venipuncture in the phlebotomy laboratory regardless of diagnosis. The convenience sample consisted of 118 children aged 3 to 18 years undergoing painful

REL|ABtLITY AND VALIDITY OF PAIN SCALES

371

A limitation of the study was a characteristic of 3-year-olds included in the sample. Initially, the research assistants eliminated any 3-yearold who could not count to 10. In addition, anecdotal data suggested that some 3-year-olds could not understand the instruments and were not included in the sample. Therefore, the sample of 3-year-olds may have been biased in favor of those who could understand the instruments.

procedures. Eighty-four percent of the children experienced venipuncture, identified by children as one of the most painful procedures they experience (Fradet, McGrath, Kay, Adams & Luke, 1990; Wong & Baker, 1988). The sample was evenly split regarding gender with 50% boys and 50% girls. Eighty-four percent of the children were White, 14% were African American and 2% were of other ethnic origins. Children as young as 3-years-old have been shown to be able to provide self-reports of the amount of pain they experience (Maunuksela et al., 1987; Wong & Baker, 1988). However, the literature routinely refers to concerns that the younger children may not be able to respond adequately to self-report tools (Aradine et al., 1988; Beyer & Aradine, 1986; McGrath & Unruh, 1987; Villarruel & Denyes, 1981). Therefore, the children were subdivided into three groups according to Piaget's three major cognitive stages of verbal children as follows: preoperational children ages 3 to 7 years (N = 37), concrete operations children ages 8 to 12 years (N = 42), and formal operations children ages 13 to 18 years (N = 38). All analyses were conducted both within and across the three age groups.

L No Pain 0

The four pain rating scales were strategically placed on one 8 inch by 11 inch sheet of heavy paper (Figure 1). The sheet was then folded in fourths so that each scale could be shown to the children without their being able to view the other scales. To control for order of presentation, six forms of the instrument were used, each with scales placed in a different order. Instruments were then randomly selected for data collection before the procedure and again after the procedure. An additional instrument, containing only the Faces and Word Descriptor Scales, was used to obtain test-retest reliability assessments. The Word Descriptor Scale was scored by

I Little 1

0

No Pain I o

INSTRUMENTS

i Medium 2

1

I 1

I 2

Figure 1. Studyscales: (top to bottom) Word Descriptor Scales,

I

FACES Scale, Numeric Scale, and Word Graphic Scale.

No Pain

I Quite a lot 3

I Very bad 4

3

4

2

I 3

Little Pain

I 4

I 5

Medium

pain

I 6

I 7

Large pain

I 8

I Worst Pain

J

Worst Pain 5

5

Worst Pain I 9 10 I

372

KECK ET AL

asking the children to point out or verbally indicate the words which best described how much pain they were having. Scores could range from 0 for no pain to 5 for worst pain. The children were asked to respond to the Faces scale by telling the researcher which face showed how much hurt the child was feeling. The children were told that the first face showed a child who was happy because the child didn't hurt at all. Potential scores ranged from 0 for no pain to 5 for "hurts as much as you can imagine." The numerical scale was scored by asking the children to point out or verbally indicate the number ranging from 0 to 10 which represented the amount of pain they were having. The children responded to the Word Graphic Scale by using a pencil to place a vertical mark on the 100 mm line at the place that represented how much pain they were having. Scores ranged from 0 for no pain to 100 for worst pain.

PROCEDURE Approval to conduct the study was obtained by the University Institutional Review Board and a committee charged with reviewing all nursing studies conducted within the Hospital. Parents and children were approached in the waiting room of the Hematology-OncologyClinic and the phlebotomy lab. The study was explained followed by an invitation to participate extended to both parent and child. Clinic nurses informed the researchers of potential study members when possible. Otherwise, any child accompanied by a parent in the waiting room was approached. If both parent and child were willing, informed consent was obtained and the child was shown how to use the four scales. Typically, parents stayed with the child during data collection and the painful procedure. Data were collected at three time periods, (1) immediately before the procedure, (2) immediately after the end of the procedure, and (3) 15 minutes after the second measure. Data were collected during an 18 month period by four research assistants. Training sessions for the research assistants were held before initiation of the study. Training was conducted by the project coordinator, a registered nurse with 7 years experience in a pediatric setting.

RESULTS Discriminant Validity Discriminant validity for both the Faces and Word Descriptor Scales was supported by lack of correlation between data obtained when a child is not in pain before the procedure and those obtained after the painful procedure. Low, nonsignificant Pearson correlations between the pre- and postprocedure measurements (Table 1) and significant differences in pain scores between the two measures based on paired t-tests were observed (Table 2).

Concurrent Validity The data obtained immediately after the procedure were used to assess concurrent validity of the scales. Concurrent validity of the Faces and Word Descriptor Scales was supported by high significant Pearson correlations between these scales and others known to be valid measures of pain in pediatric populations. Validity and reliability of both the Numerical and Word Graphic scales have been reported (AHCPR, 1992). Validity was supported by moderate to high, statistically significant correlations when the Faces and Word Descriptor Scales were compared with the Word Graphic and Numerical Scales (Table 3). Three of the children who provided pain ratings were diagnosed as developmentally delayed or learning disabled. The data collector determined that these children were unable to use the Word Graphic Scale. Their data were excluded from data analysis for concurrent validity.

Test-Retest Reliability Data for the Faces and Word Descriptor Scales were collected immediately after the painful procedure and again 15 minutes later. The 15 minute time lapse was selected to limit dependence on remembered rather than actual Table 1. Discriminant Validity Analysis ofthe FACESand

Word Descriptor Scales Based on Pearson Correlation Tool FACES

Word Descriptor

Age

r

p

N

Total Sample

-.06

ns

118

3-7

-.03

ns

37

8-12

-.19

ns

42

13-18

.20

ns

38

3-7

-.04 -.07

ns ns

118 37

8-12

-.09

ns

42

13-18

.04

ns

38

Total Sample

RELIABILITYAND VALIDITY OF PAIN SCALES

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Table 2. Discriminant Analysis of the FACES and Word Descriptor Scales Based on Paired t-tests Scale FACES Preprocedure Postprocedure Word Descriptor Scale Preprocedure Postprocedure

Mean

SD

df

t

.49 1.61

.85 1.43

109

6.87

.001

.38 1.33

.73 1.29

108

-6.59

.001

FACES

internal Consistency Reliability Internal Consistency reliability is not measurable with a one-item scale and is, therefore, not directly assessable for either the Faces or Word Descriptor Scales. One may obtain an indirect indication of consistency of pain measurement for both scales if the four study scales are incorporated into one theoretical pain rating instrument with 4 items, each scale representing one of the items. Before analysis, scores were converted to z-scores because of the differences in score range for each scale (6-point vs. 100point scales, for example). The reliability analysis was conducted using the data from the second measurement time immediately after the procedure with data from 110 children. A Cronbach Alpha of .93 was obtained providing an indirect indication of consistency reliability.

Extraneous Variables Because the literature suggests that children may differ in ability to use the pain rating scales, differences in responses to the Faces and Word Descriptor Scales were compared across the three age groups. No significant differences in Table 3. Concurrent Validity Analysis of the FACES and Word Descriptor Scales Criterion Instruments Word Graphic (VAS) NumericalScale

Study Age

r

N

r

N

TotalSample 3-7 8-12 13-18

.71" .63* .79* .66*

118 37 42 38

.75* .75* .71" .81"

118 37 42 38

Word Descri~or TotaISample 3-7 8-12 13-18

.89* .92* .84* .91"

118 37 42 38

.76" .67* .85* .82*

118 37 42 38

FACES

*Significant at p

>

.01.

Scale

p

pain ratings. Test-retest reliability was supported by high, statistically significant Pearson correlations between the two postprocedure measurements (Table 4).

Scale

Table 4. Test-Retest Reliability Analysis of the FACES and Word Descriptor Scales

Word Descriptor

*Significant at p

>

Age

r

N

Total Sample 3-7 8-12 13-18 Total Sample 3-7 8-12 13-18

.90" .83* .96* .93* .92* .90* .96* .88*

118 37 42 38 118 37 42 38

.001.

pain ratings for any of the pre- or postprocedure measures were found. In addition, no significant differences were found for gender or months since diagnosis for any of the four scales at any of the three measurement times.

Scale Preference Scale preference was assessed by asking the children to relate which scale, if any, they liked best. Twelve of the children (10%) had no preference. The percentage of children in each age group preferring each scale is found in Table 5. No significant differences in preference were found when comparing the three age groups (Chi Square = 9.7, p = .14). We had expected that the older children would prefer the Word Descriptor or numerical scales. The majority of children in each age group preferred the FACES Scale.

DISCUSSION Both the Faces and the modified Word Descriptor Scales received psychometric support for discriminant and concurrent validity and test-retest reliability and internal consistency reliability. Both scales could discriminate between the child with pain and the child with no pain supporting discriminant validity. Both scales were significantly correlated with instruments with known validity with moderate to high correlation values supporting concurrent validTable 5. Scale Preference for Total Sample and Each Age Group Scale Age (yrs)

N

FACES

Word Descriptor

VAS

Numerical

3-7 8-12 13-18

30 25 (83.3%) 41 26 (63.4) 35 18 (54.4%)

1 (3.3%) 3 (7.3%) 7 (20.0%)

1 (3.3%) 4 (9.8%) 3 (8.6%)

3 (10.0%) 8 (19.5%) 7 (20.0%)

Total

106 69(65.1%)

11(10.4%)

8(7.5%)

18(17.0%)

374

KECK ET AL

ity. High, statistically significant correlations supported test-retest reliability and consistent ratings among the four scales provided indirect support for internal consistency reliability of the Faces and Word Descriptor Scales. The findings suggest that the instruments are valid and reliable tools when used to assess procedural pain among verbal children aged 4- to 18-years and among 3-year-olds who can count and understand the instruments. In addition, the Faces Scale was preferred by all children, including the adolescents. The study findings support the credibility of the Faces and Word Descriptor Scales to assess pain intensity on a pain management flow sheet among verbal children.

Reliability and validity of the Faces and Word Descriptor Scales was supported for children with procedural pain. Both scales have the potential to contribute to improved pain management by facilitating the assessment and documentation of pain and pain relief for children. They are cost-effective and easily incorporated in a documentation system that can be kept by each child's bedside. They are preferred by nurses and a majority of children and are usable among children of varying cognitive abilities experiencing painful procedures. Research is needed to investigate validity and reliability of the Faces and Word Descriptor Scales among other patient populations in inpatient and outpatient settings.

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