- Email: [email protected]
Reliability and validity of the Spanish version of the modified Yale Preoperative Anxiety Scale
Rev Esp Anestesiol Reanim. 2016;63(6):320---326
Revista Española de Anestesiología y Reanimación www.elsevier.es/redar
ORIGINAL ARTICLE
Reliability and validity of the Spanish version of the modified Yale Preoperative Anxiety Scale夽 C. Jerez a,∗ , A.M. Ullán b , J.J. Lázaro c a
Unidad de Cirugía Ambulatoria, Hospital Materno-Infantil Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Spain Facultad de Ciencias Sociales, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain c Departamento de Anestesiología y Reanimación, Hospital Materno-Infantil Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Spain b
Received 29 May 2015; accepted 18 September 2015 Available online 17 March 2016
KEYWORDS Validation studies; Preoperative period; Child behaviour; Anxiety; Coping behaviour; Ambulatory care
Abstract Introduction and objective: To minimise preoperative stress and increase child cooperation during induction of anaesthesia is one of the most important perioperative objectives. The modified Yale Preoperative Anxiety Scale was developed to evaluate anxiety. The aim of this study was to translate into Spanish, and validate the psychometric properties of the Spanish version of this scale. Material and methods: The Spanish translation of the scale was performed following the World Health Organisation guidelines. During induction of anaesthesia, 81 children aged 2---12 years were recorded. Two observers evaluated the recordings independently. Content validity index of modified Yale Preoperative Anxiety Scale Spanish version was assessed. Weighted Kappa was calculated to measure interobserver agreement, and the Pearson correlation between the Induction Compliance Checklist and the modified Yale Preoperative Anxiety Scale was determined. Results: The Spanish version obtained high content validity (0.91---0.98). Reliability analysis using weighted Kappa statistics revealed that interobserver agreement ranged from 0.54 to 0.75. Concurrent validity was high (r = 0.94; p < .001). Conclusions: Validated assessment tools are needed to evaluate interventions to reduce child preoperative anxiety. The Spanish version of the modified Yale Preoperative Anxiety Scale evaluated in this study has shown good psychometric properties of reliability and validity. © 2015 Sociedad Espa˜ nola de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España, S.L.U. All rights reserved.
夽
Please cite this article as: Jerez C, Ullán AM, Lázaro JJ. Fiabilidad y validez de la versión espa˜ nola de la escala de evaluación de la ansiedad prequirúrgica pediátrica modified Yale Preoperative Anxiety Scale. Rev Esp Anestesiol Reanim. 2016;63:320---326. ∗ Corresponding author. E-mail address: [email protected] (C. Jerez). 2341-1929/© 2015 Sociedad Espa˜ nola de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España, S.L.U. All rights reserved.
Reliability and validity of the Spanish version of the mYPAS
PALABRAS CLAVE Estudios de validación; Periodo preoperatorio; Comportamiento infantil; Ansiedad; Adaptación psicológica; Atención ambulatoria
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Fiabilidad y validez de la versión espa˜ nola de la escala de evaluación de la ansiedad prequirúrgica pediátrica modified Yale Preoperative Anxiety Scale Resumen Introducción y objetivo: Minimizar el estrés preoperatorio y aumentar la cooperación del ni˜ no durante la inducción de la anestesia es uno de los objetivos más importantes de los programas perioperatorios. La escala modified Yale Preoperative Anxiety Scale fue desarrollada para evaluar la ansiedad preoperatoria de los ni˜ nos. El propósito de este estudio fue traducir al espa˜ nol y validar las propiedades psicométricas de esta versión en espa˜ nol. Material y métodos: La traducción al espa˜ nol de la escala se realizó siguiendo la guía de la Organización Mundial de la Salud. Durante la inducción de la anestesia, se grabaron 81 ni˜ nos de 2 a 12 a˜ nos. Dos observadores evaluaron las grabaciones de forma independiente. Se valoró el índice de validez de contenido. Se calculó el índice Kappa ponderado para medir el acuerdo interobservadores y se determinó el coeficiente de correlación de Pearson con la escala de comportamiento Induction Compliance Checklist. Resultados: La versión en espa˜ nol de la escala obtuvo un índice de validez de contenido elevado (0,91-0,98). La fiabilidad se evaluó con el índice Kappa ponderado, revelando un acuerdo interobservadores de 0,54 a 0,75. La validez concurrente fue elevada (r = 0,94; p < 0,001). Conclusiones: Son necesarias herramientas estandarizas y válidas para evaluar las intervenciones que se realizan para reducir la ansiedad del ni˜ no que va a ser operado. La versión en espa˜ nol de la modified Yale Preoperative Anxiety Scale evaluada en este estudio ha mostrado buenas propiedades psicométricas de fiabilidad y validez. © 2015 Sociedad Espa˜ nola de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. Todos los derechos reservados.
Introduction Surgery can be a stressful experience, particularly for children. Some authors have recommended reducing preoperative anxiety in these patients, not only to improve their level of cooperation with the surgical team, but also for humanitarian reasons.1 Reducing anxiety can also improve postoperative outcomes,2 as extreme preoperative anxiety is closely linked to postoperative distress. A variety of strategies have been developed to minimise preoperative stress: premedication with anxiolytics, videos, hospital clowns, music therapy, or allowing parents to be present during anaesthesia induction.3 Irrespective of the method used, it is important to evaluate whether the goal of the stress-reducing strategy has been met, in other words, whether it succeeded in reducing the child’s anxiety. The effectiveness of these strategies can be measured by means of validated, reliable perioperative anxiety scales, the most widely used being the modified Yale Preoperative Anxiety Scale (mYPAS). This scale has been used in over 100 studies to date,4 and has been translated into and validated in several different languages.5,6 The mYPAS7 consists of 22 items grouped into 5 categories: Activity, Vocalizations, Emotional Expressivity, State of Arousal and Use of Parent. Each category consists of 4 items, except for the ‘‘vocalizations’’ category, which has 6. As each category contains a different number of items, the overall score is weighted, and ranges from 23.3 to 100 (weighted score). A score of 30 or over indicates a state of anxiety.
The first version, the Yale Preoperative Anxiety Scale,8 was developed in 1995 to evaluate anxiety in children aged between 2 and 6 years. It was later amended in 1997 (mYPAS)7 to broaden the scope to include children of up to 12 years of age. In 2014, Jenkins et al.4 published a second, shorter version in which they removed the ‘‘use of parent’’ category to allow the scale to be used in operating rooms where parents were not able to accompany their child during anaesthesia induction. In this study, we describe the process followed in translating and adapting the mYPAS scale to Spanish, and the procedure used to evaluate the psychometric properties of the new version in a sample of children aged between 2 and 12 years scheduled to undergo surgery in the Day Surgery Clinic of a paediatric hospital.
Materials and methods This study of the validation of the Spanish version of the mYPAS was conducted in 2 phases. In the first phase, the scale was translated into Spanish using forward and back translation techniques; in the second phase, the reliability and validity of the scale were evaluated.
Phase 1: forward and back translation Once permission to translate the mYPAS into Spanish had been obtained from the original authors,7 it was translated and back translated following the recommendations of the World Health Organisation9 (Fig. 1). The original scale was
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Spanish version of mYPAS
Back translation of mYPAS
Back translations compared and agreed
Translations compared and agreed
Original version of mYPAS
Spanish version of mYPAS
Back translation of mYPAS
Final version of mYPAS
Figure 1
Preliminary test. Evaluation of anxiety
Translation and transcultural adaptation to Spanish of the modified Yale Preoperative Anxiety Scale.
translated independently into Spanish by two bilingual translators. Both translations were reviewed by an expert panel consisting of 3 perioperative nurses, 1 paediatric anaesthesiologist, and 1 psychologist specialising in the validation and reliability of scales, and a single version was agreed by consensus. The version approved by the expert panel was then back translated into English and compared with the English original to identify and resolve conceptual differences. Finally, 2 perioperative nurses independently used the translated scale to evaluate the level of anxiety of 10 children the preoperative holding area of the Day Surgery Clinic. The scores were compared, differences were discussed, and on this basis the definitive version of the Spanish MYPAS was drafted (Appendix online).
Phase II: analysis of the reliability and validity of the scale Participants The study was conducted in a paediatric hospital in Barcelona. Study subjects were 110 children aged between 2 and 12 years, undergoing major day surgery between October and December 2013. Prior to inclusion, the study was explained to all parents and a signed informed consent form was obtained. Exclusion criterion was no command of Spanish (parents). The study was approved by the Research Ethics Committee of our hospital (C. I. PIC-72-14). The study data forms part of the database of an observational study on preoperative anxiety conducted in our unit. Procedure On the day of surgery, the study was explained to the child and their parents, and the patient’s details were collected: age, sex, type of surgery scheduled, surgical history and previous hospitalisations. On the basis of the preoperative interview with both the child and the parents, the nurse detected signs of rejection, stress, negation, nervousness, avoidance strategies, etc. Children exhibiting these behaviours were reported to
the anaesthetist, who administered an anxiolytic. In our hospital, 0.2 mg/kg oral midazolam is given 20---30 min before surgery. The mYPAS scale was administered to all children. The usual routine followed in the unit was not changed in any way during the study. The surgery was explained to all children; they were taught how to use the facemask, and either watched television or a performance by a clown. Both parents were allowed to be present during anaesthesia induction if they so wished. Anaesthesia induction from the time the child was placed on the operating table up to total loss of consciousness was recorded by a camera placed in a safe location. Anaesthesia was induced by inhalation (through a facemask) of incremental doses of sevoflurane in 33% O2 /N2 O up to a peak concentration of 8%. The anaesthesiologist in charge of induction evaluated the child’s behaviour on the Induction Compliance Checklist (ICC).10 The ICC is a list of reactions and behaviours that can be exhibited by the child when the facemask is applied during induction. The final score, which ranges from 1 to 10, is the sum of all observed reactions. A score of 0 indicates that the child cooperated during induction and did not reject the facemask. A high score on this scale indicates rejection by the child, and a high level of anxiety, fear or stress. The ICC scale was adapted to Spanish by our group using the forward and back translation process. It has shown excellent inter-observer reliability, with an intraclass correlation coefficient of 0.956 (95% CI; p < 0.001), and good internal consistency reliability (˛ = 0.927; 95% CI; p < 0.01). Table 1 shows the Spanish ICC scale used in this study. The video recordings made during induction were viewed separately and independently by an expert perioperative nurse (observer 1) and a psychologist (observer 2). Statistical analysis: reliability and validity Microsoft® Excel® 2011 was used to calculated the weighted Kappa and the content validity index (CVI), and the remaining calculations were made using SPSS® version 22. Descriptive data are shown as number of cases, mean and
Reliability and validity of the Spanish version of the mYPAS
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Table 1 Spanish version of the Induction Compliance Checklist (with English back translation) used in this study.
Table 2 Sample size, sex, sedation, type of intervention and company during induction.
Llora, lágrimas en los ojos [Crying, tears in eyes] Gira la cabeza, no quiere la mascarilla [Turns head away from mask] Verbaliza negación, dice «no» [Verbal refusal, says ‘no’] Verbaliza miedo o preocupación: «¿dónde está mi mamá?»,«¿me dolerá?» [Verbalizes fear or worry ‘‘Where’s mummy?’’, ‘‘Will it hurt?’’] Se quita la mascarilla con las manos, empuja con manos o pies a la enfermera o el anestesista [Pushes mask away with hand, pushes nurse or anaesthetist away with hands or feet] Se cubre la boca/nariz con las manos, se cubre la cara con los brazos [Covers mouth/nose with hands, cover face with arms] Llora histéricamente, chilla [Hysterical crying, screaming] Da patadas, golpea con las piernas/brazos, se aparta, lucha [Kicks, flails legs/arms, arches back, fights] Requiere sujeción física [Requires physical restraint] Completamente pasivo, rígido o flácido [Complete passivity, rigid or flaccid]
Total
81
Age in yearsa Sex (boys/girls) Premedication (no/yes) Surgical history (no/yes/not available)
5.41 ± 2.2 67/14 58/23 56/23/2
Surgical intervention Circumcision Herniorrhaphy Cryptorchidism/bilateral herniorrhaphy Frenulum/cyst/naevus
31 12 23 15
Accompanies child during induction Parents Parents and clowns Clowns
17 30 23
Total score = sum of items selected (Induction Compliance Checklist [ICC] = 1---10) ICC = 0, perfect induction, shows no negative behaviour, fear or anxiety. Original English version: Kain et al.10
standard deviation. Inter-observer reliability, comparing the independent evaluations of the anaesthesia induction video as rated by observers 1 and 2, was determined using the Kappa index. Kappa values were interpreted using the values suggested by Altman, as reported in López de Ullibarri and Pita Fernández.11 Agreement was poor if Kappa was <0.20; weak if it was between 0.21 and 0.40; moderate if it was between 0.41 and 0.60; good if it was between 0.61 and 0.80; and very good if it was between 0.81 and 1.00. Cohen’s weighted Kappa12 was also calculated to take into account inter-observer disagreement. The CVI was evaluated to ensure that the content of the scale was sufficiently broad.13 Each observer viewed the recordings and chose the item from each category that best described the child’s behaviour or reactions. Each item was given a score of 1---4, with 1 point being ‘‘does not apply’’ and 4 being ‘‘fully applies’’. The CVI of the mYPAS was calculated on the basis of the percentage of all items rated 3 or 4 by the observers. CVI ≥0.80 indicated a high level of validity.13 Concurrent validity (how the scale correlated to another scale evaluating the same construct) was determined using Pearson’s correlation coefficient for the mYPAS against the ICC. Pearson’s correlation coefficient ranges from 0 to 1, with 1 being the highest level of agreement. Following the example of the original authors,7 construct validity was evaluated on the basis of the difference in mYPAS scores between the preoperative holding area and application of the face mask. After performing the Kolmogorov---Smirnov test, the paired Student’s t test was used to analyse differences in mYPAS scores in nonpremedicated children, and the Wilcoxon rank test was used for differences in premedicated children.
a
Mean ± standard deviation.
Results Of the 110 inductions we were given permission to record, 4 were excluded due to technical problems with the camera, 3 were excluded due to suspension of the intervention, and 3 were excluded after the parents refused permission to record induction. Ten recordings were used by the observers (1 and 2) to agree on the Spanish version of the mYPAS, and were therefore not included in the analysis, and 9 recordings were incomplete and therefore unsuitable for use in the analysis. A total of 81 recordings were independently analysed by 2 observers. Table 2 shows the results of the descriptive analysis. Of 81 children included in the analysis, 21% were accompanied by their parents during induction, 28.4% were accompanied by the clowns, 37% were accompanied by both the clowns and their parents, and only 13.6% were accompanied solely by medical personnel. The mean age of the sample was 5 ± 2.2 years. In total, 82.7% (n = 67) of the sample was boys, and 28.4% of the total sample was classified as anxious.
Validity of the content Ten recordings were used by the expert panel to agree on the mYPAS during anaesthesia induction. After viewing the recordings, the observers considered that the behaviour of some children was not reflected in the scale. On this basis, it was decided to add the item ‘‘blows through the face mask according to instructions’’ to the activity category, and in the vocalisation category, blowing was added to the descriptor ‘‘children are too young to speak in social situations, or too absorbed in play to respond’’; both were included in item 1. The remaining evaluations were made with these items added to the scale. As shown in Table 3, the CVI was high in 4 categories.
Inter-observer reliability Table 4 shows the level of inter-observer agreement during evaluation of the anxiety behaviours shown in the
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Table 3 Content validity index by Spanish modified Yale Preoperative Anxiety Scale categories during anaesthesia induction. Observer 2
0.98 0.98 0.98 0.99 0.58
0.94 0.77 0.90 0.91 0.43
80.00
mYPAS
Activity Vocalisation Emotional Expressivity State of Arousal Use of Parent
Observer 1
100.00
60.00
Good content validity if score ≥0 80 (according to Denise and Bernadette13 ).
40.00
recordings. Inter-observer agreement in the different categories ranged from moderate to good.
20.00
60 37
0
<4
≥4
ICC
Concurrent validity A correlation was observed between anxiety evaluated on the mYPAS and the child’s behaviour evaluated on the ICC during anaesthesia induction (Fig. 2). Correlation between mYPAS and ICC and between observers, analysed using the Pearson coefficient, was high (r = 0.86 and p 0.001 for observer 1, and r = 0.94 and p < 0.001 for observer 2).
Figure 2 Correlation between the Spanish versions of the modified Yale Preoperative Anxiety Scale and the Induction Compliance Checklist during anaesthesia induction. The diagram shows the differences in the mean between the anxiety score and observed behaviour categorised according to Varughese et al.22 ; Induction Compliance Checklist (ICC) = 0 (compliant, does not resist application of face mask); ICC <4 (compliant, with slight resistance); ICC ≥4 (non-compliant, actively resists induction and needs to be physically restrained).
Validity of the content The mYPAS score ranged from 23.33 to 90 (mean = 36.75) in the preoperative holding area, and from 22.92 to 100 (mean = 41.48) during anaesthesia induction. This shows significant differences between anxiety scores in the preoperative holding area and during anaesthesia induction in non-premedicated children (p = 0.031), and non-significant difference in scores between premedicated children (p = 0.08).
Discussion The aim of this study was to determine the reliability and validity of the Spanish version of the mYPAS in a sample of children aged between 2 and 12 years. The content validity of the Spanish version of the mYPAS has been shown to be excellent in all categories, except for 1: ‘‘use of parent’’.
This is because this category was evaluated in all study subjects, and it was rated ‘‘does not apply’’ in children that were not accompanied by their parents during anaesthesia induction. This category could have been eliminated in the case of children that were not accompanied by their parents during anaesthesia induction, as shown by the authors of the short version of the mYPAS.4 While this would not have affected the scale itself, it would have increased CVI. In the remaining categories, our findings show that CVI correlated with the Kappa coefficient; this means that the higher the Kappa index agreement, the higher the CVI.14 In this study, we chose to use Cohen’s Kappa index,15 as this statistic adjusts the agreement rate for random guesses. The mYPAS includes 2 new behaviours in item 1 of the ‘‘activity’’ and ‘‘vocalisation’’ categories. This does not affect the scale, but rather adapts it to the reality observed
Table 4 Inter-observer agreement (observer 1 [CJ] vs observer 2 [AU]) for the modified Yale Preoperative Anxiety Scale evaluated after each observer had independently viewed the anaesthesia induction video recordings. mYPAS in anaesthesia induction
Agreement (%)
Inter-observer agreement (Kappa)
Weighted Kappaa (Kw)
Strength of agreement
Activity Vocalisation Emotional expressivity State of Arousal Use of Parent
80.3 61.8 68 76.6 45.9
0.52 0.31 0.53 0.55 0.32
0.65 0.55 0.69 0.75 0.54
Good Moderate Good Good Moderate
mYPAS: modified Yale Preoperative Anxiety Scale. a Kappa strength of agreement (taken from López de Ullibarri and Pita Fernández11 ): <0.20 poor; 0.21---0.40 weak; 0.41---0.60 moderate; 0.61---0.80 good; 0.81---1.00 very good.
Reliability and validity of the Spanish version of the mYPAS in preoperative holding rooms. A similar change was made in the Swedish5 and Danish6 versions of the scale. In terms of reliability, video recordings of anaesthesia induction were used to evaluate inter-observer agreement, similar to the process used in previous versions of the mYPAS5,6 The results show good to moderate agreement, and are similar to those reported by the authors of the Swedish version of the scale.5 The ICC scale was used to evaluate concurrent validity. Some authors have found a strong association between the behaviour exhibited by the child during anaesthesia induction and the level of anxiety of the parents.16,17 This relationship between the child’s behaviour and parental anxiety was also found in our study. The means of the mYPAS score also differed between premedicated and non-premedicated children. In our study, midazolam, an anxiolytic drug commonly administered to children before an intervention,18 was given at a dose of 0.2 mg/kg. Previous studies have reported that preoperative midazolam reduced anxiety in paediatric surgical patients.19,20 In our study, we found that premedicated children were less anxious during anaesthesia induction, although the differences were not significant. The midazolam dose administered was probably insufficient to obtain statistical significance. The anxiety score in children not receiving preoperative midazolam, however, was significantly higher during induction than in the preoperative holding room. This confirms that anaesthesia induction is the most stressful moment during the perioperative period.7 These results are consistent with those reported by the authors of the Swedish version of the scale.5 This study has some limitations. Firstly, no children with developmental delays were included, which prevented us from determining whether the Spanish version of the mYPAS shows the same psychometric properties in this population. The second limitation involves the use of the ICC scale to determine concurrent validity. In this study, the ICC scale was used in accordance with forward and back translation criteria and reliability results. Our group is currently working on validating this scale with other instruments. Despite these limitations, we consider that the Spanish version of the mYPAS shows good psychometric properties. The scale could be difficult to use in routine clinical practice, as it requires a certain learning curve and must be administered by trained personnel.5,21 Nevertheless, there are a number of advantages in translating and validating a Spanish version of this scale. Firstly, it can be used to evaluate anxiety in paediatric surgical patients at various preoperative time points. This can be of benefit in studies aimed at evaluating the effectiveness of strategies developed to reduce preoperative anxiety in children. Secondly, the use of a validated Spanish version of an internationally accepted scale will permit authors to compare their findings with those reported in other studies, a comparison that is almost impossible when different measuring instruments are used. This study has shown the psychometric properties of the Spanish version of the mYPAS scale for this paediatric age group in these circumstances. Based on our findings, we can safely say that the Spanish version of the mYPAS is a reliable, valid instrument and a valuable tool for use in studies evaluating preoperative anxiety in Spanish speaking children.
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Conflicts of interest The authors have no conflicts of interest.
Acknowledgements We would like to thank the children and parents who agreed to take part in this study, and in particular, we would like to thank the nursing staff of the Day Clinic for their contribution.
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.redare. 2016.02.001.
References 1. Watson AT, Visram A. Children’s preoperative anxiety and postoperative behaviour. Paediatr Anaesth. 2003;13:188---204. 2. Kain ZN, Caldwell-Andrews AA, Maranets I, McClain B, Gaal D, Mayes LC, et al. Preoperative anxiety and emergence delirium and postoperative maladaptive behaviors. Anesth Analg. 2004;99:1648---54. 3. Yip P, Middleton P, Cyna AM, Carlyle AV. Non-pharmacological interventions for assisting the induction of anaesthesia in children. Cochrane Database Syst Rev. 2009;3:CD006447. 4. Jenkins BN, Fortier MA, Kaplan SH, Mayes LC, Kain ZN. Development of a short version of the modified Yale Preoperative Anxiety Scale. Anesth Analg. 2014;119:643---50. 5. Proczkowska-Björklund M, Gimbler Berglund I, Ericsson E. Reliability and validity of the Swedish version of the modified Yale Preoperative Anxiety Scale. Acta Anaesthesiol Scand. 2012;56:491---7. 6. Skovby P, Rask CU, Dall R, Aagaard H, Kronborg H. Face validity and inter-rater reliability of the Danish version of the modified Yale Preoperative Anxiety Scale. Dan Med J. 2014;61:1---6. 7. Kain ZN, Mayes LC, Cicchetti DV, Bagnall AL, Finley JD, Hofstadter MB. The Yale Preoperative Anxiety Scale: how does it compare with a gold standard? Anesth Analg. 1997;85:783---8. 8. Kain ZN, Mayes LC, Cicchetti DV, Caramico LA, Spieker M, Nygren MM, et al. Measurement tool for preoperative anxiety in young children: the Yale Preoperative Anxiety Scale. Child Neuropsychol. 1995;1:203---10. 9. World Health Organization (WHO). Management of substance abuse. Process of translation and adaptation of instruments. Available from: http://www.who.int/substance abuse/ research tools/translation/en/ [accessed 02.09.13]. 10. Kain ZN, Mayes LC, Wang SM, Caramico LA, Hofstadter MB. Parental presence during induction of anesthesia versus sedative premedication: which intervention is more effective? Anesthesiology. 1998;89:1147---56. 11. López de Ullibarri I, Pita Fernández S. Medidas de concordancia: el índice de Kappa. Cad Aten Primaria. 1999;6:169---71. 12. Cohen J. Weighted kappa: nominal scale agreement with provision for scaled disagreement or partial credit. Psychol Bull. 1968;70:213---20. 13. Denise P, Bernadette H. Investigación científica en ciencias de la salud. 6th ed. México: Editorial McGraw-Hill Interamericana; 2000. 14. Orts-Cortés MI, Moreno-Casbas T, Squires A, Fuentelsaz-Gallego C, Maciá-Soler L, González-María E. Content validity of the
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C. Jerez et al. Spanish version of the Practice Environment Scale of the Nursing Work Index. Appl Nurs Res. 2013;26:5---9. Cohen J. A coefficient of agreement for nominal scales. Educ Psychol Meas. 1960;XX:37---46. Bong CL, Ng AS. Evaluation of emergence delirium in Asian children using the Pediatric Anesthesia Emergence Delirium Scale. Paediatr Anaesth. 2009;19:593---600. Berghmans J, Weber F, van Akoleyen C, Utens E, Adriaenssens P, Klein J, et al. Audiovisual aid viewing immediately before pediatric induction moderates the accompanying parents’ anxiety. Paediatr Anaesth. 2012;22:386---92. Linares Segovia B, García Cuevas M, Ramírez Casillas I, Gerrrero Romero J, Botello Buenrostro I, Monroy Torres R, et al. Medicación preanestésica con dexmedetomidina intranasal y midazolam oral como ansiolítico. Un ensayo clínico. An Pediatr. 2014;81:226---31.
19. Kain ZN, Caldwell-Andrews AA, Krivutza DM, Weinberg ME, Wang S-M, Gaal D. Trends in the practice of parental presence during induction of anesthesia and the use of preoperative sedative premedication in the United States, 1995---2002: results of a follow-up national survey. Anesth Analg. 2004;98:1252---9. 20. Rosenbaum A, Kain ZN, Larsson P, Lönnqvist P-A, Wolf AR. The place of premedication in pediatric practice. Paediatr Anaesth. 2009;19:817---28. 21. Bringuier S, Dadure C, Raux O, Dubois A, Picot MC, Capdevila X. The perioperative validity of the visual analog anxiety scale in children: a discriminant and useful instrument in routine clinical practice to optimize postoperative pain management. Anesth Analg. 2009;109:737---44. 22. Varughese AM, Nick TG, Gunter J, Wang Y, Kurth CD. Factors predictive of poor behavioral compliance during inhaled induction in children. Anesth Analg. 2008;107:413---21.
Revista Española de Anestesiología y Reanimación www.elsevier.es/redar
ORIGINAL ARTICLE
Reliability and validity of the Spanish version of the modified Yale Preoperative Anxiety Scale夽 C. Jerez a,∗ , A.M. Ullán b , J.J. Lázaro c a
Unidad de Cirugía Ambulatoria, Hospital Materno-Infantil Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Spain Facultad de Ciencias Sociales, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain c Departamento de Anestesiología y Reanimación, Hospital Materno-Infantil Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Spain b
Received 29 May 2015; accepted 18 September 2015 Available online 17 March 2016
KEYWORDS Validation studies; Preoperative period; Child behaviour; Anxiety; Coping behaviour; Ambulatory care
Abstract Introduction and objective: To minimise preoperative stress and increase child cooperation during induction of anaesthesia is one of the most important perioperative objectives. The modified Yale Preoperative Anxiety Scale was developed to evaluate anxiety. The aim of this study was to translate into Spanish, and validate the psychometric properties of the Spanish version of this scale. Material and methods: The Spanish translation of the scale was performed following the World Health Organisation guidelines. During induction of anaesthesia, 81 children aged 2---12 years were recorded. Two observers evaluated the recordings independently. Content validity index of modified Yale Preoperative Anxiety Scale Spanish version was assessed. Weighted Kappa was calculated to measure interobserver agreement, and the Pearson correlation between the Induction Compliance Checklist and the modified Yale Preoperative Anxiety Scale was determined. Results: The Spanish version obtained high content validity (0.91---0.98). Reliability analysis using weighted Kappa statistics revealed that interobserver agreement ranged from 0.54 to 0.75. Concurrent validity was high (r = 0.94; p < .001). Conclusions: Validated assessment tools are needed to evaluate interventions to reduce child preoperative anxiety. The Spanish version of the modified Yale Preoperative Anxiety Scale evaluated in this study has shown good psychometric properties of reliability and validity. © 2015 Sociedad Espa˜ nola de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España, S.L.U. All rights reserved.
夽
Please cite this article as: Jerez C, Ullán AM, Lázaro JJ. Fiabilidad y validez de la versión espa˜ nola de la escala de evaluación de la ansiedad prequirúrgica pediátrica modified Yale Preoperative Anxiety Scale. Rev Esp Anestesiol Reanim. 2016;63:320---326. ∗ Corresponding author. E-mail address: [email protected] (C. Jerez). 2341-1929/© 2015 Sociedad Espa˜ nola de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España, S.L.U. All rights reserved.
Reliability and validity of the Spanish version of the mYPAS
PALABRAS CLAVE Estudios de validación; Periodo preoperatorio; Comportamiento infantil; Ansiedad; Adaptación psicológica; Atención ambulatoria
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Fiabilidad y validez de la versión espa˜ nola de la escala de evaluación de la ansiedad prequirúrgica pediátrica modified Yale Preoperative Anxiety Scale Resumen Introducción y objetivo: Minimizar el estrés preoperatorio y aumentar la cooperación del ni˜ no durante la inducción de la anestesia es uno de los objetivos más importantes de los programas perioperatorios. La escala modified Yale Preoperative Anxiety Scale fue desarrollada para evaluar la ansiedad preoperatoria de los ni˜ nos. El propósito de este estudio fue traducir al espa˜ nol y validar las propiedades psicométricas de esta versión en espa˜ nol. Material y métodos: La traducción al espa˜ nol de la escala se realizó siguiendo la guía de la Organización Mundial de la Salud. Durante la inducción de la anestesia, se grabaron 81 ni˜ nos de 2 a 12 a˜ nos. Dos observadores evaluaron las grabaciones de forma independiente. Se valoró el índice de validez de contenido. Se calculó el índice Kappa ponderado para medir el acuerdo interobservadores y se determinó el coeficiente de correlación de Pearson con la escala de comportamiento Induction Compliance Checklist. Resultados: La versión en espa˜ nol de la escala obtuvo un índice de validez de contenido elevado (0,91-0,98). La fiabilidad se evaluó con el índice Kappa ponderado, revelando un acuerdo interobservadores de 0,54 a 0,75. La validez concurrente fue elevada (r = 0,94; p < 0,001). Conclusiones: Son necesarias herramientas estandarizas y válidas para evaluar las intervenciones que se realizan para reducir la ansiedad del ni˜ no que va a ser operado. La versión en espa˜ nol de la modified Yale Preoperative Anxiety Scale evaluada en este estudio ha mostrado buenas propiedades psicométricas de fiabilidad y validez. © 2015 Sociedad Espa˜ nola de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. Todos los derechos reservados.
Introduction Surgery can be a stressful experience, particularly for children. Some authors have recommended reducing preoperative anxiety in these patients, not only to improve their level of cooperation with the surgical team, but also for humanitarian reasons.1 Reducing anxiety can also improve postoperative outcomes,2 as extreme preoperative anxiety is closely linked to postoperative distress. A variety of strategies have been developed to minimise preoperative stress: premedication with anxiolytics, videos, hospital clowns, music therapy, or allowing parents to be present during anaesthesia induction.3 Irrespective of the method used, it is important to evaluate whether the goal of the stress-reducing strategy has been met, in other words, whether it succeeded in reducing the child’s anxiety. The effectiveness of these strategies can be measured by means of validated, reliable perioperative anxiety scales, the most widely used being the modified Yale Preoperative Anxiety Scale (mYPAS). This scale has been used in over 100 studies to date,4 and has been translated into and validated in several different languages.5,6 The mYPAS7 consists of 22 items grouped into 5 categories: Activity, Vocalizations, Emotional Expressivity, State of Arousal and Use of Parent. Each category consists of 4 items, except for the ‘‘vocalizations’’ category, which has 6. As each category contains a different number of items, the overall score is weighted, and ranges from 23.3 to 100 (weighted score). A score of 30 or over indicates a state of anxiety.
The first version, the Yale Preoperative Anxiety Scale,8 was developed in 1995 to evaluate anxiety in children aged between 2 and 6 years. It was later amended in 1997 (mYPAS)7 to broaden the scope to include children of up to 12 years of age. In 2014, Jenkins et al.4 published a second, shorter version in which they removed the ‘‘use of parent’’ category to allow the scale to be used in operating rooms where parents were not able to accompany their child during anaesthesia induction. In this study, we describe the process followed in translating and adapting the mYPAS scale to Spanish, and the procedure used to evaluate the psychometric properties of the new version in a sample of children aged between 2 and 12 years scheduled to undergo surgery in the Day Surgery Clinic of a paediatric hospital.
Materials and methods This study of the validation of the Spanish version of the mYPAS was conducted in 2 phases. In the first phase, the scale was translated into Spanish using forward and back translation techniques; in the second phase, the reliability and validity of the scale were evaluated.
Phase 1: forward and back translation Once permission to translate the mYPAS into Spanish had been obtained from the original authors,7 it was translated and back translated following the recommendations of the World Health Organisation9 (Fig. 1). The original scale was
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Spanish version of mYPAS
Back translation of mYPAS
Back translations compared and agreed
Translations compared and agreed
Original version of mYPAS
Spanish version of mYPAS
Back translation of mYPAS
Final version of mYPAS
Figure 1
Preliminary test. Evaluation of anxiety
Translation and transcultural adaptation to Spanish of the modified Yale Preoperative Anxiety Scale.
translated independently into Spanish by two bilingual translators. Both translations were reviewed by an expert panel consisting of 3 perioperative nurses, 1 paediatric anaesthesiologist, and 1 psychologist specialising in the validation and reliability of scales, and a single version was agreed by consensus. The version approved by the expert panel was then back translated into English and compared with the English original to identify and resolve conceptual differences. Finally, 2 perioperative nurses independently used the translated scale to evaluate the level of anxiety of 10 children the preoperative holding area of the Day Surgery Clinic. The scores were compared, differences were discussed, and on this basis the definitive version of the Spanish MYPAS was drafted (Appendix online).
Phase II: analysis of the reliability and validity of the scale Participants The study was conducted in a paediatric hospital in Barcelona. Study subjects were 110 children aged between 2 and 12 years, undergoing major day surgery between October and December 2013. Prior to inclusion, the study was explained to all parents and a signed informed consent form was obtained. Exclusion criterion was no command of Spanish (parents). The study was approved by the Research Ethics Committee of our hospital (C. I. PIC-72-14). The study data forms part of the database of an observational study on preoperative anxiety conducted in our unit. Procedure On the day of surgery, the study was explained to the child and their parents, and the patient’s details were collected: age, sex, type of surgery scheduled, surgical history and previous hospitalisations. On the basis of the preoperative interview with both the child and the parents, the nurse detected signs of rejection, stress, negation, nervousness, avoidance strategies, etc. Children exhibiting these behaviours were reported to
the anaesthetist, who administered an anxiolytic. In our hospital, 0.2 mg/kg oral midazolam is given 20---30 min before surgery. The mYPAS scale was administered to all children. The usual routine followed in the unit was not changed in any way during the study. The surgery was explained to all children; they were taught how to use the facemask, and either watched television or a performance by a clown. Both parents were allowed to be present during anaesthesia induction if they so wished. Anaesthesia induction from the time the child was placed on the operating table up to total loss of consciousness was recorded by a camera placed in a safe location. Anaesthesia was induced by inhalation (through a facemask) of incremental doses of sevoflurane in 33% O2 /N2 O up to a peak concentration of 8%. The anaesthesiologist in charge of induction evaluated the child’s behaviour on the Induction Compliance Checklist (ICC).10 The ICC is a list of reactions and behaviours that can be exhibited by the child when the facemask is applied during induction. The final score, which ranges from 1 to 10, is the sum of all observed reactions. A score of 0 indicates that the child cooperated during induction and did not reject the facemask. A high score on this scale indicates rejection by the child, and a high level of anxiety, fear or stress. The ICC scale was adapted to Spanish by our group using the forward and back translation process. It has shown excellent inter-observer reliability, with an intraclass correlation coefficient of 0.956 (95% CI; p < 0.001), and good internal consistency reliability (˛ = 0.927; 95% CI; p < 0.01). Table 1 shows the Spanish ICC scale used in this study. The video recordings made during induction were viewed separately and independently by an expert perioperative nurse (observer 1) and a psychologist (observer 2). Statistical analysis: reliability and validity Microsoft® Excel® 2011 was used to calculated the weighted Kappa and the content validity index (CVI), and the remaining calculations were made using SPSS® version 22. Descriptive data are shown as number of cases, mean and
Reliability and validity of the Spanish version of the mYPAS
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Table 1 Spanish version of the Induction Compliance Checklist (with English back translation) used in this study.
Table 2 Sample size, sex, sedation, type of intervention and company during induction.
Llora, lágrimas en los ojos [Crying, tears in eyes] Gira la cabeza, no quiere la mascarilla [Turns head away from mask] Verbaliza negación, dice «no» [Verbal refusal, says ‘no’] Verbaliza miedo o preocupación: «¿dónde está mi mamá?»,«¿me dolerá?» [Verbalizes fear or worry ‘‘Where’s mummy?’’, ‘‘Will it hurt?’’] Se quita la mascarilla con las manos, empuja con manos o pies a la enfermera o el anestesista [Pushes mask away with hand, pushes nurse or anaesthetist away with hands or feet] Se cubre la boca/nariz con las manos, se cubre la cara con los brazos [Covers mouth/nose with hands, cover face with arms] Llora histéricamente, chilla [Hysterical crying, screaming] Da patadas, golpea con las piernas/brazos, se aparta, lucha [Kicks, flails legs/arms, arches back, fights] Requiere sujeción física [Requires physical restraint] Completamente pasivo, rígido o flácido [Complete passivity, rigid or flaccid]
Total
81
Age in yearsa Sex (boys/girls) Premedication (no/yes) Surgical history (no/yes/not available)
5.41 ± 2.2 67/14 58/23 56/23/2
Surgical intervention Circumcision Herniorrhaphy Cryptorchidism/bilateral herniorrhaphy Frenulum/cyst/naevus
31 12 23 15
Accompanies child during induction Parents Parents and clowns Clowns
17 30 23
Total score = sum of items selected (Induction Compliance Checklist [ICC] = 1---10) ICC = 0, perfect induction, shows no negative behaviour, fear or anxiety. Original English version: Kain et al.10
standard deviation. Inter-observer reliability, comparing the independent evaluations of the anaesthesia induction video as rated by observers 1 and 2, was determined using the Kappa index. Kappa values were interpreted using the values suggested by Altman, as reported in López de Ullibarri and Pita Fernández.11 Agreement was poor if Kappa was <0.20; weak if it was between 0.21 and 0.40; moderate if it was between 0.41 and 0.60; good if it was between 0.61 and 0.80; and very good if it was between 0.81 and 1.00. Cohen’s weighted Kappa12 was also calculated to take into account inter-observer disagreement. The CVI was evaluated to ensure that the content of the scale was sufficiently broad.13 Each observer viewed the recordings and chose the item from each category that best described the child’s behaviour or reactions. Each item was given a score of 1---4, with 1 point being ‘‘does not apply’’ and 4 being ‘‘fully applies’’. The CVI of the mYPAS was calculated on the basis of the percentage of all items rated 3 or 4 by the observers. CVI ≥0.80 indicated a high level of validity.13 Concurrent validity (how the scale correlated to another scale evaluating the same construct) was determined using Pearson’s correlation coefficient for the mYPAS against the ICC. Pearson’s correlation coefficient ranges from 0 to 1, with 1 being the highest level of agreement. Following the example of the original authors,7 construct validity was evaluated on the basis of the difference in mYPAS scores between the preoperative holding area and application of the face mask. After performing the Kolmogorov---Smirnov test, the paired Student’s t test was used to analyse differences in mYPAS scores in nonpremedicated children, and the Wilcoxon rank test was used for differences in premedicated children.
a
Mean ± standard deviation.
Results Of the 110 inductions we were given permission to record, 4 were excluded due to technical problems with the camera, 3 were excluded due to suspension of the intervention, and 3 were excluded after the parents refused permission to record induction. Ten recordings were used by the observers (1 and 2) to agree on the Spanish version of the mYPAS, and were therefore not included in the analysis, and 9 recordings were incomplete and therefore unsuitable for use in the analysis. A total of 81 recordings were independently analysed by 2 observers. Table 2 shows the results of the descriptive analysis. Of 81 children included in the analysis, 21% were accompanied by their parents during induction, 28.4% were accompanied by the clowns, 37% were accompanied by both the clowns and their parents, and only 13.6% were accompanied solely by medical personnel. The mean age of the sample was 5 ± 2.2 years. In total, 82.7% (n = 67) of the sample was boys, and 28.4% of the total sample was classified as anxious.
Validity of the content Ten recordings were used by the expert panel to agree on the mYPAS during anaesthesia induction. After viewing the recordings, the observers considered that the behaviour of some children was not reflected in the scale. On this basis, it was decided to add the item ‘‘blows through the face mask according to instructions’’ to the activity category, and in the vocalisation category, blowing was added to the descriptor ‘‘children are too young to speak in social situations, or too absorbed in play to respond’’; both were included in item 1. The remaining evaluations were made with these items added to the scale. As shown in Table 3, the CVI was high in 4 categories.
Inter-observer reliability Table 4 shows the level of inter-observer agreement during evaluation of the anxiety behaviours shown in the
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Table 3 Content validity index by Spanish modified Yale Preoperative Anxiety Scale categories during anaesthesia induction. Observer 2
0.98 0.98 0.98 0.99 0.58
0.94 0.77 0.90 0.91 0.43
80.00
mYPAS
Activity Vocalisation Emotional Expressivity State of Arousal Use of Parent
Observer 1
100.00
60.00
Good content validity if score ≥0 80 (according to Denise and Bernadette13 ).
40.00
recordings. Inter-observer agreement in the different categories ranged from moderate to good.
20.00
60 37
0
<4
≥4
ICC
Concurrent validity A correlation was observed between anxiety evaluated on the mYPAS and the child’s behaviour evaluated on the ICC during anaesthesia induction (Fig. 2). Correlation between mYPAS and ICC and between observers, analysed using the Pearson coefficient, was high (r = 0.86 and p 0.001 for observer 1, and r = 0.94 and p < 0.001 for observer 2).
Figure 2 Correlation between the Spanish versions of the modified Yale Preoperative Anxiety Scale and the Induction Compliance Checklist during anaesthesia induction. The diagram shows the differences in the mean between the anxiety score and observed behaviour categorised according to Varughese et al.22 ; Induction Compliance Checklist (ICC) = 0 (compliant, does not resist application of face mask); ICC <4 (compliant, with slight resistance); ICC ≥4 (non-compliant, actively resists induction and needs to be physically restrained).
Validity of the content The mYPAS score ranged from 23.33 to 90 (mean = 36.75) in the preoperative holding area, and from 22.92 to 100 (mean = 41.48) during anaesthesia induction. This shows significant differences between anxiety scores in the preoperative holding area and during anaesthesia induction in non-premedicated children (p = 0.031), and non-significant difference in scores between premedicated children (p = 0.08).
Discussion The aim of this study was to determine the reliability and validity of the Spanish version of the mYPAS in a sample of children aged between 2 and 12 years. The content validity of the Spanish version of the mYPAS has been shown to be excellent in all categories, except for 1: ‘‘use of parent’’.
This is because this category was evaluated in all study subjects, and it was rated ‘‘does not apply’’ in children that were not accompanied by their parents during anaesthesia induction. This category could have been eliminated in the case of children that were not accompanied by their parents during anaesthesia induction, as shown by the authors of the short version of the mYPAS.4 While this would not have affected the scale itself, it would have increased CVI. In the remaining categories, our findings show that CVI correlated with the Kappa coefficient; this means that the higher the Kappa index agreement, the higher the CVI.14 In this study, we chose to use Cohen’s Kappa index,15 as this statistic adjusts the agreement rate for random guesses. The mYPAS includes 2 new behaviours in item 1 of the ‘‘activity’’ and ‘‘vocalisation’’ categories. This does not affect the scale, but rather adapts it to the reality observed
Table 4 Inter-observer agreement (observer 1 [CJ] vs observer 2 [AU]) for the modified Yale Preoperative Anxiety Scale evaluated after each observer had independently viewed the anaesthesia induction video recordings. mYPAS in anaesthesia induction
Agreement (%)
Inter-observer agreement (Kappa)
Weighted Kappaa (Kw)
Strength of agreement
Activity Vocalisation Emotional expressivity State of Arousal Use of Parent
80.3 61.8 68 76.6 45.9
0.52 0.31 0.53 0.55 0.32
0.65 0.55 0.69 0.75 0.54
Good Moderate Good Good Moderate
mYPAS: modified Yale Preoperative Anxiety Scale. a Kappa strength of agreement (taken from López de Ullibarri and Pita Fernández11 ): <0.20 poor; 0.21---0.40 weak; 0.41---0.60 moderate; 0.61---0.80 good; 0.81---1.00 very good.
Reliability and validity of the Spanish version of the mYPAS in preoperative holding rooms. A similar change was made in the Swedish5 and Danish6 versions of the scale. In terms of reliability, video recordings of anaesthesia induction were used to evaluate inter-observer agreement, similar to the process used in previous versions of the mYPAS5,6 The results show good to moderate agreement, and are similar to those reported by the authors of the Swedish version of the scale.5 The ICC scale was used to evaluate concurrent validity. Some authors have found a strong association between the behaviour exhibited by the child during anaesthesia induction and the level of anxiety of the parents.16,17 This relationship between the child’s behaviour and parental anxiety was also found in our study. The means of the mYPAS score also differed between premedicated and non-premedicated children. In our study, midazolam, an anxiolytic drug commonly administered to children before an intervention,18 was given at a dose of 0.2 mg/kg. Previous studies have reported that preoperative midazolam reduced anxiety in paediatric surgical patients.19,20 In our study, we found that premedicated children were less anxious during anaesthesia induction, although the differences were not significant. The midazolam dose administered was probably insufficient to obtain statistical significance. The anxiety score in children not receiving preoperative midazolam, however, was significantly higher during induction than in the preoperative holding room. This confirms that anaesthesia induction is the most stressful moment during the perioperative period.7 These results are consistent with those reported by the authors of the Swedish version of the scale.5 This study has some limitations. Firstly, no children with developmental delays were included, which prevented us from determining whether the Spanish version of the mYPAS shows the same psychometric properties in this population. The second limitation involves the use of the ICC scale to determine concurrent validity. In this study, the ICC scale was used in accordance with forward and back translation criteria and reliability results. Our group is currently working on validating this scale with other instruments. Despite these limitations, we consider that the Spanish version of the mYPAS shows good psychometric properties. The scale could be difficult to use in routine clinical practice, as it requires a certain learning curve and must be administered by trained personnel.5,21 Nevertheless, there are a number of advantages in translating and validating a Spanish version of this scale. Firstly, it can be used to evaluate anxiety in paediatric surgical patients at various preoperative time points. This can be of benefit in studies aimed at evaluating the effectiveness of strategies developed to reduce preoperative anxiety in children. Secondly, the use of a validated Spanish version of an internationally accepted scale will permit authors to compare their findings with those reported in other studies, a comparison that is almost impossible when different measuring instruments are used. This study has shown the psychometric properties of the Spanish version of the mYPAS scale for this paediatric age group in these circumstances. Based on our findings, we can safely say that the Spanish version of the mYPAS is a reliable, valid instrument and a valuable tool for use in studies evaluating preoperative anxiety in Spanish speaking children.
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Conflicts of interest The authors have no conflicts of interest.
Acknowledgements We would like to thank the children and parents who agreed to take part in this study, and in particular, we would like to thank the nursing staff of the Day Clinic for their contribution.
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.redare. 2016.02.001.
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19. Kain ZN, Caldwell-Andrews AA, Krivutza DM, Weinberg ME, Wang S-M, Gaal D. Trends in the practice of parental presence during induction of anesthesia and the use of preoperative sedative premedication in the United States, 1995---2002: results of a follow-up national survey. Anesth Analg. 2004;98:1252---9. 20. Rosenbaum A, Kain ZN, Larsson P, Lönnqvist P-A, Wolf AR. The place of premedication in pediatric practice. Paediatr Anaesth. 2009;19:817---28. 21. Bringuier S, Dadure C, Raux O, Dubois A, Picot MC, Capdevila X. The perioperative validity of the visual analog anxiety scale in children: a discriminant and useful instrument in routine clinical practice to optimize postoperative pain management. Anesth Analg. 2009;109:737---44. 22. Varughese AM, Nick TG, Gunter J, Wang Y, Kurth CD. Factors predictive of poor behavioral compliance during inhaled induction in children. Anesth Analg. 2008;107:413---21.