The burn specific pain anxiety scale: introduction of a reliable and valid measure

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0 1997 Eisevier

Burns Vol. 23,No.2,pp. 147-150,1997 Science Ltd for ISBI. All rights reserved Printed in Great Britain

0305-4179/97 $17.00 + 0.00

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The burn

specific pain anxiety scale: of a reliable and valid measure

intro

L. A. TaaY and A. W. Faber” ‘Humanist Counsellor Burn Centre, Zuiderziekenhuis Rotterdam, Groenehilledijk 315, Rotterdam, The Netherlands and 2Clinical Psychologist Burn Centre, Martiniziekenhuis, Groningen, The Netherlands The burn specific pain anxiety scale (BSPAS) is a nine-item selfreport scale for the assessment of pain-related and anticipatory anxiety in burned patients. This paperdescribes a study designed to explorethe psychometric propertiesof the scale. The study used 35 burned patients hospitalized in Rotterdamand Groningen, The Netherlands, to confirm the internal consistency of the instrument anid provide an assessment of its validity. The cx coefficient was high: 0.94. The BSPAS correlated statistica!ly sigmficanflywith the STAI-S, procedural pain, non-procedu,val pain, and nurses’ visual analog observation ratings of tension. 0 1997 ElsevierScience Ltd for ISBI. All rights reserved. Key words: Pain, anxiety, self-report scale.

Burns, Vol. 25, No. 2, 147-150,1997

changes, confrontation with wounds and multiple surgical procedures), its operation description and assessmentseparately from related concepts, such as general anxiety and neuroticism, seemsappropriate. This paper focuses on the introduction of a nineitem self-rating scale, the burn specific pain anxiety scale (BSPAS), for detecting feelings of anxiety and worry in patients with burns. The goal of this study was to develop a very short, uni-dimensional scale and to run a reliability and validity study on it. This study compares the responses of 35 burned patients on the STAI-S, the BSPAS, patients’ visual analog ratings of pain, and nurses’ observation ratings of tension immediately before and during the dressing change.

Introduction A major characteristic of the long and difficult period of hospitalization of the burned patient is prolonged, severe pain’. Melzack et al.2 found that anxiety, depression and pain were, not surprisingly, interrelated in burned patients. They used the state-version of the state-trait anxiety inventory (STAI-S)3, administered to the patients just before wound dressing change, to assess anxious anticipation of pain. The correlations between levels of pain and STAI-S scores were, however, not statistically significant. Although the STAT-S is fairly short, we nevertheless consider it to be too long for use in a hospital. Moreover, the questions are not related to the specific situation wi.th which the burned patient is confronted. A need exists for an instrument which is reliable, validly reflects the essential elements of burn specific anxiety, and allows for differentation of levels of anxiety severity in these patients. As we could not find a clinically applicable instrument in the literature which fullfilled all our requirements, i.e. short and specifically attuned to the situation of th.e patient with burns, we decided to develop a new instrument. Since the anxiety of the burned patient is clea:rly situa.tion-specific (painful daily wound dressing

Methods Sample Participants were burn patients hospitalized in the burn units in Rotterdam and Groningen between October 1994 and October 1995. Inclusion criteria for this study required the patients: (a) to be Dutchspeaking; (b) to be older than 16 years of age; and (c) to have no premorbid psychiatric diagnosis. During the aforementioned period, 55 patients met the described inclusion criteria. However, we used the BSPAS only in the period between January and October 1995. Therefore, data for the reliability and validity study on the BSPAS were available on 35 subjects. The mean numbers of days on which the BSPAS and STAI-S were given after admission was 7 days (range 6-10). The sample (N= 35) was composed of 28 males and 7 females with a mean age of 32.2 years, and a range of 16-74 years. The burns of the sample averaged a mean body surface area of 16.3 per cent (SD=8.7). The mean number of days in the hospital of the sample was 22 days (SD = 8.7). The data presented are from 2310 tension ratings of treating nurses and 3850 pain ratings of patients.

Burns: Vol. 23, No. 2,1997

148

Tools Buxn specific pain anxiety scale The BSPAS con-

sists of nine items which describe: (1) feelings of worry about wound healing; (2) tension and fear of losing control during dressing changes; (3) anxious anticipation of pain during or after medical procedures; and (4) a generalized feeling of being ‘keyed up’ or ‘on edge’ because of enduring pain. The items are scored on a 100 mm visual analog line with two reference points given values of 0 and 100. The reference points are identified by these numbers, and also by the expressions ‘not at all‘ and ‘the worst imaginable way’. There is no middleranged reference position or ‘neutral’ point on this patients are visual analog line. In the instruction, explicitly requested to scale the strength of their feelings relative to the two reference points, thus making ratio responses. State-trait anxiety inventory (STAI) The STAI is a validated, self-report instrument designed to measure state (STAI-S) and trait anxiety (STAI-T), which has been transla.ted into Dutch and validated by van der Ploeg et a1.4, The questionnaire consists of two separate 20-item rating scales for measuring trait and. state anxiety. The trait anxiety scale evaluates individual differences in the relatively stable disposition to experience anxiety. The state anxiety scale measures situation-related anxiety. State-anxiety may differ depending on the stress of the particular moment. The STAI-S has been used in several anaesthesioIogical studie?.

A thermometer analog as described elsewhere by

Visual analog thermometer

for measuring pain Chioniere et al.6.

scale A 100 mm visual analog line with the expressions ‘no tension at all and ‘the worst tension imaginable’ as reference points.

Visual analog observation

Procedure

The researchers conducted from October 1994 to February 1995 several open interviews to collect statem.ents they could use to build a scale. From January 1995 to April 1995, 18 patients were administered a 27-item BSPAS and the STAI-S 7 days after admission. The nine current BSPAS items were, after inspection of the item-total correlations, derived from these 27 items. From April 1995 to October 1995, 17 patients were adminstered the final nine-item version of the BSPAS and the STAI-S. Between October 1995 and October 1996 the nurse asked the patient to provide pain ratings five times a day: (a) at 08.00 h, (b) immediately before dressing change, (c) immediately after dressing change with the request to rate the pain at its strongest point during the procedure,

(d) at 16.00 h, (e) at 22.00 h. Three times a day: (a) at 08.00 h, (b) immediately (c) immediately

before the dressing change, after the dressing change.

The nurse marked a position on a 100 mm visual analog observation scale according to the level of the observed degree of tension in a patient.

Results Reliability

Reliability is the most fundamental aspect of psychological measurement; there was, of course, no need to consider validity of the BSPAS if reliability could not be established first. The data obtained with the BSPAS were submitted to multivariate analyses in order to assess the instrument’s reliability. Cronbach’s CI provides a reliability estimate that simultaneously considers all the possible ways of splitting the test items in an interitem correlational matrix. Reliability was considered to be acceptable when M>0.70. The coefficient c[ was quite high, 0.94, suggesting that the nine BSPAS items as a whole measure the same construct. Another measure of internal consistency that was applied to the data was the average item-total correlation, the Pearson correlation coeffiicient between the score on each individual item and the sum of the scores on the remaining items. On average, the itemtotal correlation was 0.76 (p
In order to test the extent to which the BSPAS measures what it purports to measure, pain and procedure related anxiety-state in burn patients, we performed several correlational analyses. Attention was devoted mainly to some aspects of criterion validity. First, as a measure of concurrent validity we determined the correlation of the BSPAS with the STAI-S and the visual analog observation scales. We hypothesized that the BSPAS should correlate statisTatble I. Item-total -

correlations

for BSP’AS

Item 1. 2. 3. 4. 5. 6. 7. 8. 9. -

Worry about wound-healing Fear of procedural pain Fear of losing control because of pain Fear of pain during dressing change Pain severity Keyed up because of enduring pain Concern about wound healing Preoccupied with pain Tension during dressing change

&em-total

correlation 0.82 0.80 0.77 0.78 0.76 0.73 0.88 0.76 0.76

Taal and Faber: The BSPAS: introduction

of a reliable

and valid measure

Table II. Correlations between BSPAS, STAI-S, percentage day’s tension observation ratings above 75, procedural and non-procedural pain in 35 burn patients 4 1 2 3 5 __~ 1. 2. 3. 4. 5. --

BSPAS STAI-S Procedural pain Non-procedural pain Tension ratings 75

*p
1.00 0.58"" 0.59”” 0.38” 0.44*

1.00 0.48" 0.18 NS 0.28 NS

1 .oo 0.70** 0.51*

1.00 0.45"

1.00

**P<0.005.

tically significantly with both the STAI-S and the nurses’ visual analog observation scales. The correlation between the STAI-S and the BSPAS (0.58, ~~0.005, see Table II) indicated a statistically significant degree of covariation between the two anxiety-state scales. In order to test the hypothesis that the BSPAS correlates statistically significantly with the nurses’ visual analog observation ratings of tension immediately before and during dressing change, we decided to calculate, for every patient, the percentage of days where one of the three observation ratings was above 75. With this decision, which is also justifiable because the reported correlations between nurses’ and patients ratings of tension in previous studies were generally low7, we avoided sham-accuracy and bypassed the need for a ruler to precisely measure placement of the mark on 2310 observation scales, which woul~d be a very tedious and time consuming affair. Table 2 shows that, as expected, the correlations between the percentage of the days nurs,es considerated a patient very tense and the BSPAS was statistically significant (0.44, p < 0.05). The correlation between the STAI-S and the visual analog observation scales was, however, not statistically significant (0.18, NS). Second, the validity of the BSPAS was further evaluated by another correlational analysis. We hypothesized that if the BSPAS measures painrelated anxiety, it should correlate highly with procedu.ral pain and should have a lower correlation with non-procedural pain. We averaged all the patients’ procedural and non-procedural pain ratings and computed the correlation coefficient between the pain variables, the BSPAS and the STAI-S. As expected, the BSPAS had a high correlation with procedural pain, but rather a low correlation with non-procedural pain. The correlation between the STAI-S and the pain variables shows the same tendency.

149

Measures of internal consistency indicate that the scale is a reliable unidimensional instrument for the assessmentof pain-related state-anxiety and anxious cioncern about wound healing in burned patients. The BSPAS can provide nurses with an easily applicable instrument for assessing the level of patients’ anticipatory and pain-related anxiety. Using BSPAS scores, it was possible to discriminate between patients who experienced different levels of procedural pain. The BSPAS uses visual analog lines on which the reference points are chosen in such a way that there is no doubt in the mind of the patients what the positions are on their subjective scale. Terms like ‘not at all’ and ‘in the worst imaginable way‘ clearly indicate the endpoints of the scale. The choice of these terms will reduce considerably the amount of variation in the response function of the patients and in this way their responses become more comparable*. Furthermore, the present study provides empirical evidence that anxiety before and during dressing changes and before surgical procedures has a ‘-psycho-toxic’ effect: i.e. it tends to spread out over the entire day and affects the ‘belief of the patient in the healing capacity of his own body. Taking into account the rather low correlation between the STAI-S, the visual analog observation ratings and non-procedural pain, the STAI-S does not seem to be a suitable instrument to measure situation-specific state-anxiety in burned patients. A major weakness of this study was the small number of cases (N= 35). Replication of our findings with other clinical samples is needed before generalizations can be made with any degree of confidence. Despite the limitations of the present study, the results indicate that the BSPAS is an appropriate measurement instrument for anticipatory and painrelated anxiety in burn patients.

Acknowledgements This work was financially supported by the Dutch Burn Foundation. The authors thank H. Boxma, H. J. Klasen and D. I’. Ma&e for their critical review of the manuscript. This research project was made possible by the generous collaboration of the nursing staff of the burn units of the Zuiderziekenhuis :Rotterdam and the Martiniziekenhuis Groningen. Finally, we appreciate Mrs E. Sondervan’s valuable assistancein preparing the manuscript.

Discussion

References

The purpose of this study was to develop a stateanxiety scale for use in a burn unit. For this reason, a nine-item questionnaire was developed: the burn specific pain anxiety scale (BSPAS). The BSPAS was easily and very quickly completed by patients. The results of this study indicate that the BSPAS is a promising instrument for field work in a burn unit.

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344-348.

Melzack R, Choiniere M, Rondeau J ,2t al. The pain of burns: characteristics and correlates. J Trawra 1989; 29: 1531-1539. 3 Spielberger CD, Gorsuch R, Lushene RE. Manual for the StuteTrait Anxiety Inventory. Palo Alto: Consulting Psychogists Press, 1979. 2

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16: 165-171.

Burns: Vol. 23, No. 2,1997 8 SarisWE. Variation in Response Functions: A Source of Measurement Error in Attitude Research. Amsterdam: Sociometric Research Foundation, 1988.

Paper accepted 28 August 1996.

Correspondence should be addressed to: L. A. Taal, Burn Centre, Zuiderziekenhuis Rotterdam, Groenehilledijk 315, 3075EA Rotterdam, The Netherlands and A. W. Faber, Burn Centre, Martiniziekenhuis, P.0. Box 30033, 9700 RM Grmoningen, The Netherlands.