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Psychometric characteristics of the Turkish version of the pain flexibility scale for children with cancer

Published:September 21, 2021DOI:https://doi.org/10.1016/j.pedn.2021.09.011

      Highlights

      • Children with cancer experience pain of varying severity, depending on the disease or its treatment
      • Determining the acceptance of pain in pediatric oncology patients will shed light on intervention studies in this area.
      • The Pain Flexibility Scale for children with cancer is valid and reliable in Turkey

      Abstract

      Purpose

      This study was conducted to evaluate the validity and reliability of the Pain Flexibility Scale for children with cancer in Turkey.

      Design and method

      This was a methodological–descriptive–correlational study conducted on 211 children with cancer. Data were collected using the information form and Pain Flexibility Scale for children with cancer. The data were evaluated using explanatory and confirmatory factor analysis, Cronbach's alpha, split-half, item-total score correlation, and test-retest analysis.

      Results

      The explained variance rate of the scale, in which factor analysis confirmed the two-dimensional structure, was 85.31%. The factor loads were greater than 0.30, and all fit indices were greater than 0.90. In addition, RMSEA was less than 0.080 and was significant. The total Cronbach's alpha value of the scale was 0.82, and the Cronbach's alpha values of its sub-dimensions were 0.82 and 0.79.

      Conclusions

      The Pain Flexibility Scale for children with cancer is a valid and reliable measurement tool for the Turkish sample.

      Practice implications

      Pain Flexibility Scale facilitates the development of psychological interventions based on acceptance, which can enable children with cancer to cope more successfully with pain.

      Keywords

      Introduction

      One of the most prevalent symptoms in pediatric oncology patients is pain, which exerts negative consequences on their quality of life (
      • Linder
      • Hooke M.C.
      Symptoms in children receiving treatment for cancer—Part II: Pain, sadness, and symptom clusters.
      ). Pain is experienced by children as a consequence of the illness, cancer treatment side effects, and/or medical processes (
      • Kristjánsdóttir Ó.
      • Unruh A.M.
      • McAlpine L.
      • McGrath P.J.
      A systematic review of cross-cultural comparison studies of child, parent, and health professional outcomes associated with pediatric medical procedures.
      ;
      • Twycross A.
      • Parker R.
      • Williams A.
      • Gibson F.
      Cancer-Related Pain and Pain Management: Sources, Prevalence, and the Experiences of Children and Parents.
      ). Pain triggers anxiety in children with cancer, which can increase the experience/level/ intensity of the pain (
      • Cioffi I.
      • Michelotti A.
      • Perrotta S.
      • Chiodini P.
      • Ohrbach R.
      Effect of somatosensory amplification and trait anxiety on experimentally induced orthodontic pain.
      ;
      • Hedén L.
      • Pöoder U.
      • von Essen L.
      • Ljungman G.
      Parents’ perceptions of their child’s symptom burden during and after cancer treatment.
      ). Psychological acceptance of pain has been reported, especially in children with chronic pain (
      • Pielech M.
      • Vowles K.E.
      • Wicksell R.
      Acceptance and commitment therapy for pediatric chronic pain: Theory and application.
      ;
      • Vowles K.E.
      • Witkiewitz K.
      • Sowden G.
      • Ashworth J.
      Acceptance and commitment therapy for chronic pain: Evidence of mediation and clinically significant change following an abbreviated interdisciplinary program of rehabilitation.
      ). One of the most important characteristics of flexibility is psychological acceptance (
      • McCracken L.M.
      Learning to live with the pain: Acceptance of pain predicts adjustment in persons with chronic pain.
      ). Increasing psychological acceptance in individuals is an important component of providing flexibility (
      • McCracken L.M.
      • Gutiérrez-Martínez O.
      Processes of change in psychological flexibility in an interdisciplinary group-based treatment for chronic pain based on acceptance and commitment therapy.
      ). Acceptance and commitment therapy can be applied to individuals to increase their resilience (
      • McCracken L.M.
      • Gutiérrez-Martínez O.
      Processes of change in psychological flexibility in an interdisciplinary group-based treatment for chronic pain based on acceptance and commitment therapy.
      ). In particular, acceptance and commitment therapy aims to help individuals face obstacles rather than avoid unpleasant stimuli (
      • McCracken L.M.
      Learning to live with the pain: Acceptance of pain predicts adjustment in persons with chronic pain.
      ;
      • McCracken L.M.
      • Gutiérrez-Martínez O.
      Processes of change in psychological flexibility in an interdisciplinary group-based treatment for chronic pain based on acceptance and commitment therapy.
      ). This is accomplished through enhancing psychological adaptability, which is characterized by “Having to deal with pain without responding, criticizing, or attempting to diminish it” (
      • McCracken L.M.
      Learning to live with the pain: Acceptance of pain predicts adjustment in persons with chronic pain.
      ;
      • McCracken L.M.
      • Gutiérrez-Martínez O.
      Processes of change in psychological flexibility in an interdisciplinary group-based treatment for chronic pain based on acceptance and commitment therapy.
      ). This includes actively participating in meaningful life activities during pain, rather than putting life on hold and waiting for the pain to pass (
      • Pielech M.
      • Vowles K.E.
      • Wicksell R.
      Acceptance and commitment therapy for pediatric chronic pain: Theory and application.
      ). Therefore, acceptance-based interventions witness an increase in pain tolerance and a decrease in pain intensity and pain discomfort (
      • Pielech M.
      • Vowles K.E.
      • Wicksell R.
      Acceptance and commitment therapy for pediatric chronic pain: Theory and application.
      ;
      • Vowles K.E.
      • Witkiewitz K.
      • Sowden G.
      • Ashworth J.
      Acceptance and commitment therapy for chronic pain: Evidence of mediation and clinically significant change following an abbreviated interdisciplinary program of rehabilitation.
      ;
      • Zeidan F.
      • Martucci K.T.
      • Kraft R.A.
      • Gordon N.S.
      • Mchaffie J.G.
      • Coghill R.C.
      Brain mechanisms supporting the modulation of pain by mindfulness meditation.
      ). In addition, the quality of life of children who actively participate in meaningful life activities during pain is high (
      • Buhle J.
      • Wager T.D.
      Does meditation training lead to enduring changes in the anticipation and experience of pain?.
      ;
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ).
      An attentive, unresponsive attitude to unpleasant stimuli is established in acceptance-based therapies (
      • Buhle J.
      • Wager T.D.
      Does meditation training lead to enduring changes in the anticipation and experience of pain?.
      ). The goal is to simply observe the ongoing occurrences without making any mental judgments (
      • Buhle J.
      • Wager T.D.
      Does meditation training lead to enduring changes in the anticipation and experience of pain?.
      ). This posture weakens the experience of pain and helps the sufferer better select their actions rather than reacting rigidly to situations that occur both internally and externally (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ). In a study, interventions that helped children display a non-reactive attitude to painful stimuli were applied; it was reported that pain discomfort in children decreased after the intervention (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ). Although several instruments measuring the psychological acceptance of chronic pain have been reported in the literature (
      • Reneman M.F.
      • Kleen M.
      • Trompetter H.R.
      • Schiphorst Preuper H.R.
      • Köke A.
      • van Baalen B.
      • Schreurs K.M.G.
      Measuring avoidance of pain: Validation of the acceptance and action questionnaire II-pain version.
      ;
      • Wicksell R.K.
      • Lekander M.
      • Sorjonen K.
      • Olsson G.L.
      The Psychological Inflexibility in Pain Scale (PIPS) - statistical properties and model fit of an instrument to assess change processes in pain related disability.
      ), there exist no instruments for children experiencing acute pain. Determining the acceptance of pain in pediatric oncology patients will shed light on intervention studies in this area. It will aid in the development of acceptance-based psychological therapies that can assist children with cancer who are experiencing pain in coping with their difficult circumstances (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ). Valid and reliable tools that measure pain acceptance in children with cancer are important.

      Purpose

      This study was conducted to assess the validity and reliability of the Pain Flexibility Scale for Children with Cancer in a Turkish population. The scale was developed by Cederberg et al. in 2017.

      Materials and methods

      Design

      This study was conducted methodologically to evaluate the validity and reliability of the scale of the Pain Flexibility Scale for children with cancer in Turkey.

      Sample population and sampling

      The study was conducted between November 2020 and May 2021 with children receiving pediatric hematology–oncology clinic treatment in a university hospital located in the western region of Turkey and accepting patients from neighboring cities.
      Another recommended method for sample calculation in scale development studies is the three rules, namely the rules of 5 s, 10 s, and 100 s. A researcher should take at least five people per item to perform factor analysis. If there is no problem in reaching the sample, the number of people per item should be 10 (
      • Brown T.A.
      Confirmatory factor analysis for applied research (Secon edition).
      ;
      • Finch H.W.
      Exploratory factor analysis.
      ). Because the Pain Flexibility Scale for children with cancer includes 20 items, the number of children per item was calculated as 10, and it was planned to include 200 children in the study.
      Thus, the sample was drawn using a simple random selection procedure from children aged 7 to 18 years who were undergoing cancer treatment and had volunteered to take part in the study. The study comprised 221 youngsters who freely consented to take part in the study and filled all the necessary paperwork. A pre-application was created for 10 children who consented to participate. Children who were included in the pre-application were removed from the sample, leaving 211 children in the study.
      The research data were collected using the Information Form and Pain Flexibility Scale for children with cancer.

      Information form

      The “Information Form” consisted of five questions on a child's age, gender, diagnosis, duration of diagnosis, and treatment received.

      Pain flexibility scale for children with cancer

      The Pain Flexibility Scale for children with cancer was developed by
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      . It consists of 20 items and two sub-dimensions (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ). The scale was designed to measure pain acceptance in patients with chronic pain. The valued actions subscale measures participation in meaningful activities despite the presence of pain, whereas the pain resistance sub-scale evaluates the respondent's degree of avoidance or control over pain. The scale is based on the 7-point Likert system: 0 = “I totally disagree (Never true),” 6 = “ I totally agree (Always true).” In the scale, certain items (1, 2, 3, 5, 6, 7, 8, 9, 11, 13, 14, 15, 16, 18, 20 items) are reverse coded. An increase in the scale score indicated a higher level of acceptance. Cronbach's alpha coefficient (α) of the scale varied from 0.87 to 0.91. The factor loads of the items varied from 0.44 to 0.89 (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ).

      Steps of research

      The following four steps were followed for the validity and reliability of the scales.

      Language validity stage

      The most acceptable phrase, the target language's structure should be used when translating the scale adaption. Idioms and culturally unfamiliar things should be replaced. Jenny Thorsell Cederberg, a member of the study team, provided formal permission through e-mail for the scale to be adapted to Turkish and used for the study. Three linguists independently translated the scale into Turkish. The Turkish language of the scale was adjusted using the researchers' group effort after it was translated into Turkish. The Turkish language of the scales was confirmed by a Turkish language specialist. A separate linguist specialist reverse-translated the Turkish scale into English.

      Expert opinion stage

      To evaluate the content validity of the scales, it is recommended to have at least three expert opinions (
      • Morgado F.F.R.
      • Meireles J.F.F.
      • Neves C.M.
      • Amaral A.C.S.
      • Ferreira M.E.C.
      Scale development: Ten main limitations and recommendations to improve future research practices.
      ). For the scales translated into Turkish, the opinions of five experts (a Child and Adolescent Psychiatrist, a clinical specialist psychologist, a child hematology–oncology specialist, two pediatric nursing faculty members working in this field) were obtained, and the agreement between the expert opinions was evaluated.

      Pre-trial stage

      The scale was administered to 10 children with cancer who had similar characteristics to the sample; these children were not included in the sample.

      Validity and reliability calculation stage

      To obtain the scale, the data obtained from the draft scale were created by two researchers in the research team who had documents on statistical methods.

      Statistical analysis

      The IBM SPSS Statistics 26.0 package and IBM SPSS Amos version 25.0 were used for data analysis (, ). The descriptive statistics were calculated using percentages and mean scores. The error margin was set at 0.05 while analyzing the data. Statistical methods used in the research are shown in Fig. 1.

      Ethics committee approval

      To perform the research, permission was obtained from the owners of the scales used in the research via e-mail. In addition, institutional permission was obtained from the hospital where the research was to be conducted. Ethics Committee approval was obtained from the ethics committee of a university. In this study, written consent was obtained from the parents and verbal consent from the children.

      Results

      Among the children who participated in the study, 53.1% (n = 112) were 7 to 12 years old, 46.9% (n = 99) were in the 13 to 18 years of age range, 44.5% (n = 94) were girls, 55.5% (n = 117) were boys. In addition, 40.3% (n = 85) of the children had leukemia, 30.8% (n = 65) had nervous system tumors, 17.5% (n = 37) had solid tumors, and 11.4% (n = 24) had other types of cancer. We determined that 43.6% (n = 91) of them were diagnosed with cancer 4 to 6 months ago and 75.8% (n = 160) received chemotherapy. When the causes of pain in the children participating in the study were examined, it was found out that 25.1% (n = 53) had cancer-related pain, 46.9% (n = 99) had pain as a side effect of treatment, 23.7% (n = 50) had pain due to medical procedures, and 4.3% (n = 9) reported that they experienced pain for other reasons.
      The agreement among experts ranged from 0.88 to 0.99 for each item (I-CVI), whereas it was 0.96 for the whole scale (S-CVI).
      Explanatory factor analysis results of the scale are shown in Table 1. The Promax rotation method was used in factor analysis, as in the original form of the scale. Factor analysis results confirm that the scale consists of two sub-dimensions. According to Table 1, the total explained variance rate of the scale was 85.31%. The factor loadings of the scale varied from 0.66 to 0.96.
      Table 1Results of Explanatory Factor Analysis (n:211).
      ItemsSub Scale
      Valued Action Sub ScalePain Resistance Sub Scale
      1. It's impossible to do anything when I am in pain.0.891
      2. Pain is always bad.0.964
      3. I need to focus on getting rid of the pain.0.746
      4. There are many things I can do simultaneously while being in pain.0.704
      5. Being in pain makes me worried.0.866
      6. The pain is always scary.0.802
      7. I need to control my worry over the pain.0.693
      8. Being in pain affects me very much.0.753
      9. I avoid movements or situations that might increase the pain.0.790
      10. I continue doing things even when I am in pain.0.891
      11. I have to struggle to do things when I am in pain.0.695
      12. I can focus on other things even while I am in pain.0.858
      13. The pain always feels like a threat to me.0.686
      14. The pain needs to pass before I can focus on anything else.0.802
      15. I am afraid of pain.0.888
      16. When I am in pain, I can do nothing else.0.681
      17. I feel that I can cope with the pain.0.665
      18. I can't think about anything else when I am in pain.0.710
      19. I continue to do things that are important to me even while I am in pain.0.847
      20. Being in pain is too difficult for me.0.799
      Explained Variance (%)52.79532.512
      KMO coefficient0.950
      Barlett test7824.786 (p < 0.001)
      KMO: Kaiser-Meyer Olkin coefficient.
      Confirmatory factor analysis results of the scale are shown in Table 2 and Fig. 2. The analysis results confirmed the two-dimensional scale structure. According to the confirmatory factor analysis results, factor loads ranged from 0.55 to 0.75.
      Table 2Model fit indices of the scale.
      X2DF
      Degree of Free.
      X2/DFRMSEA
      Root Mean Square Error of Approximation.
      GFI
      Goodness of Fit Index.
      CFI
      Comparative Fit Index.
      IFI
      Incremental Fit Index.
      RFI
      Relative Fit Index.
      NFI
      Normed Fit Index; TLI (NNFI): Trucker-lewıs Index.
      TLIh
      Two Factor Model389.648944.1450.0620.950.960.960.960.950.95
      a Degree of Free.
      b Root Mean Square Error of Approximation.
      c Goodness of Fit Index.
      d Comparative Fit Index.
      e Incremental Fit Index.
      f Relative Fit Index.
      g Normed Fit Index; TLI (NNFI): Trucker-lewıs Index.
      Fig. 2
      Fig. 2Confirmatory Factor Analysis of Two Factor Model.
      The α of the whole scale was determined as 0.821, Valued Action Subscale α value was 0.820, and Pain Resistance subscale α value was 0.791. The results of the split-half analysis of the scale are shown in Table 3.
      Table 3Results of the reliability analyses of the scale and sub scale (n = 211).
      Sub-dimensionsCronbach αFirst half of Cronbach αSecond half of Cronbach αSpearman-BrownGuttman split-halfCorrelation between two halvesM ± SD (Min-Max)
      Scale Total0.8210.810.820.860.860.7965.53 ± 11.54 (0−120)
      First Sub Scale0.82029.92 ± 3.11 (0–54)
      Second Sub Scale0.79135.60 ± 9.13 (0–66)
      The response bias analysis showed that Hotelling's T square value was 667.352 and F = 40.145 (p < 0.01). This result showed that there was no response bias in the scale. In addition, the summability analysis showed F = 0.682 and p = 0.840, and the scale was determined to be additive.
      The Pearson correlation analysis showed that the correlations of the items with the total score ranged from 0.46 to 0.67, and the correlations of the item-subscale scores ranged from 0.41 to 0.69 (Table 4).
      Table 4Correlations of the item total score and sub scale total score.
      ItemsX ± SDItem-Total Score Correlation
      p < 0.001.
      Item-Subscale Total Score Correlation
      p < 0.001.
      Test-Re test Correlations of Items
      p < 0.001.
      (n = 42)
      13.17 ± 1.870.920.920.92
      23.27 ± 1.740.910.910.98
      33.20 ± 1.790.910.920.99
      43.23 ± 1.880.830.810.91
      53.11 ± 1.930.930.940.98
      63.25 ± 1.780.910.910.99
      73.18 ± 1.790.930.930.92
      83.29 ± 1.920.920.940.99
      93.27 ± 1.920.930.930.96
      103.18 ± 1,840.870.860.95
      113.38 ± 1.790.940.940.99
      123.40 ± 1.880.900.910.91
      133.17 ± 1.870.900.900.98
      143.22 ± 1.900.920.920.96
      153.33 ± 1.720.940.920.94
      163.47 ± 1,650.920.920.98
      173.27 ± 1.890.890.870.99
      183.27 ± 1.640.910.910.92
      193.36 ± 2.120.860.860.95
      203.39 ± 1.720.800.810.96
      low asterisk p < 0.001.
      The Pearson Moments Multiplication Correlation or test–retest reliability coefficient was used to examine the scale's invariance after it was used twice at 4-week intervals. The test–retest scores of the measure showed a statistically significant positive correlation (r = 0.93, p = 0.000; Table 5). Student's t-test was used for dependent groups to examine if there was a difference in the mean scores at 4-week intervals from the scale (Table 5).
      Table 5Test-Retest Score Mean Obtained from the Scale and their Comparison (n = 42).
      ScalesScale Score MeanAnalysis Results
      First Implementation X ± SDSecond Implementation X ± SDrptp
      Pain Flexibility Scale65.53 ± 11.5464.45 ± 10.280.93<0.0010.520.614

      Discussion

      The I-CVI and S-CVI values above 0.80 indicate an agreement between the expert opinions (
      • Polit D.F.
      • Beck C.T.
      • Owen S.v.
      Focus on research methods: Is the CVI an acceptable indicator of content validity? Appraisal and recommendations.
      ). In this study, the I-CVI and S-CVI values were above 0.80, indicating an agreement among the experts and that the scale measured the subjects adequately.
      Important tests that evaluate the suitability and adequacy of the data for factor analysis are the Bartlett Sphericity test and Kaiser–Meyer–Olkin (KMO) analysis. The Bartlett Sphericity test result should be statistically significant, and the KMO value should be 0.60 and above for factor analysis (
      • Boateng G.O.
      • Neilands T.B.
      • Frongillo E.A.
      • Melgar-Quiñonez H.R.
      • Young S.L.
      Best practices for developing and validating scales for health, social, and behavioral research: A primer.
      ). The results of the analysis presented in Table 1 show that the database and the number of individuals participating in the study were sufficient to perform the factor analysis. The studies conducted by
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      show that the sample size is less than that in the present study; however, the factor analysis results are similar to our study (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ).
      It is emphasized that the explained variance ratio, which is an important indicator of construct validity, should be above 40% in multidimensional scales. A higher explained variance rate of the scale results in a stronger construct validity (
      • Boateng G.O.
      • Neilands T.B.
      • Frongillo E.A.
      • Melgar-Quiñonez H.R.
      • Young S.L.
      Best practices for developing and validating scales for health, social, and behavioral research: A primer.
      ;
      • Finch H.W.
      Exploratory factor analysis.
      ). The variance explained in this study was over 50%, indicating that the construct validity was strong. The explained variance rate of this study was found to be higher than the rate of the original scale (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ).
      Explanatory factor analysis is used to determine under which subdimension the items of the scale will be placed. Although it is recommended to have a minimum factor load of 0.30 and above, it is emphasized that items below 0.30 should be removed from the scale (
      • Finch H.W.
      Exploratory factor analysis.
      ). The factor loads of the items in the two subdimensions in the original form of the scale ranged from 0.44 to 0.89 (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ). The results of the present study were similar to the factor loadings in the original scale and revealed a strong factor structure.
      The majority of the literature on scale validity and reliability suggests that the structure revealed by explanatory factor analysis should be examined with confirmatory factor analysis (
      • Brown T.A.
      Confirmatory factor analysis for applied research (Secon edition).
      ;
      • Xia Y.
      • Yang Y.
      RMSEA, CFI, and TLI in structural equation modeling with ordered categorical data: The story they tell depends on the estimation methods.
      ). In this study, two subdimensions were formed, similar to the original scale. The confirmatory factor analysis determined that the root mean square error of approximation (RMSEA) value was 0.062. In addition, the chi-square value divided by the degrees of freedom (X2/df) was 4.145. In addition, the fit indices were compatible with the values suggested in the literature. In the current literature, model fit indices greater than 0.90 are accepted as an indication of a good fit. In addition, it is emphasized that the X2/df value should be less than 5 and the RMSEA value should be less than 0.08 (
      • Brown T.A.
      Confirmatory factor analysis for applied research (Secon edition).
      ;
      • Marsh H.W.
      • Guo J.
      • Dicke T.
      • Parker P.D.
      • Craven R.G.
      Confirmatory factor analysis (CFA), exploratory structural equation modeling (ESEM), and set-ESEM: Optimal balance between goodness of fit and parsimony.
      ). The CFA results in this study were found to be compatible with the criteria specified in the literature. Because the CFA results were not presented in the study in which the original scale was developed, a comparison could not be made (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ).
      The α coefficient, which should be close to 1 in scale studies, evaluates whether the items measure the same feature. In addition, it reveals whether the items are related to the subject to be measured or not. The literature recommends this value to be between 0.60 and 1.00 (
      • Nunnally J.C.
      • Bernstein I.H.
      Psychometric theory.
      ). In this study, the α values of the total and sub-dimensions of the scale were greater than 0.70. The items adequately measured the issue of pain flexibility in children and had high reliability. In the original study of the scale, α values were found to be greater than 0.80 (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ). This result shows that the scale is similar to its original structure and has a strong internal consistency.
      In the split-half analysis, one of the analyses showing the reliability level of the scale, the coefficients are expected to be more than 0.70 (
      • Chakrabartty S.
      • Nath Chakrabartty S.
      Best split-half and maximum reliability.
      ;
      • Nunnally J.C.
      • Bernstein I.H.
      Psychometric theory.
      ). The coefficients in this study were more than 0.70, indicating a strong and significant relationship between the two halves. Because the results of split-half analysis were not presented in the original study, the results of the two studies could not be (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ).
      Response bias is an important factor affecting the reliability of the scale. No response bias should be expected in a scale study. If individuals who fill out the response bias scale answer the scale according to their own opinions, the reliability of the scale is negatively affected (
      • Çapık C.
      • Gözüm S.
      • Aksayan S.
      Kültürlerarası ölçekuyarlama aşamaları, dil ve kültür uyarlaması: Güncellenmiş rehber.
      ;
      • Nunnally J.C.
      • Bernstein I.H.
      Psychometric theory.
      ). In this study, no response bias in the scale was detected as a result of Hotelling's t-test.
      To prove whether the items in the scale measure the variable to be measured, it is recommended to perform an item-total score analysis. Thus, the relationship between the scores obtained from the scale items and the total score of the scale is explained (
      • Jonhson B.
      • Christensen L.
      Educational research: Quantitative, qualitative, and mixed approaches.
      ). The acceptable value is greater than 0.20. However, it is expected to be as close to 1 as possible and in a positive direction (
      • Jonhson B.
      • Christensen L.
      Educational research: Quantitative, qualitative, and mixed approaches.
      ). In this study, the values were greater than 0.20, and there was a positive relationship. Because Pearson's correlation analysis results were not presented in the original scale study, a comparison could not be made (
      • Cederberg J.T.
      • Strandskov S.W.
      • Dahl J.A.
      • Ljungman G.
      Children’s and adolescents’ relationship to pain during cancer treatment: A preliminary validation of the pain flexibility scale for children.
      ).
      Even if the test–retest correlation coefficient is satisfactory, it is advised that the mean and standard deviations of the two measurement results be studied and that both measurement findings be identical (
      • Noble S.
      • Scheinost D.
      • Constable R.T.
      A decade of test-retest reliability of functional connectivity: A systematic review and meta-analysis.
      ). When the “t-test in dependent groups” was used to assess if there was a statistically significant difference between the mean scores in the application when completed with 4-week intervals, no statistically significant difference was observed between the mean scores (p > 0.05) (Table 5).
      Although the overall scores of the individuals may not differ significantly, they might answer each item differently. Thus, the uniformity of the materials in both applications must be considered (
      • Noble S.
      • Scheinost D.
      • Constable R.T.
      A decade of test-retest reliability of functional connectivity: A systematic review and meta-analysis.
      ). In assessing the association between the first and second application scores of each item, the test–retest reliability coefficients of the scale items were statistically significant (p = 0.000). The scale items yielded identical results in both assessments, demonstrating that the expressions were clear and consistent.

      Practice implications

      tTo achieve psychological acceptance of pain, it is necessary to first determine pain flexibility. In Turkey, a scale to assess the acute pain acceptance in children with cancer is now available, allowing researchers to investigate acceptance as a therapy change mechanism in this setting. We believe that this scale is a critical step in the development of acceptance-based psychological therapy that can help people feel better.

      Limitations

      Despite several strengths, this study had certain limitations. The first limitation of this study was that children who had all cancer types and diagnosis times were included in the study. The second limitation was the use of random sampling method in sample selection, and this could have affected the generalizability of the study. This study was conducted with children aged 7 to 18 years, as in the original scale. Therefore, it cannot be used in children aged 0 to 6 years.

      Conclusion

      This study results support that the Pain Flexibility Scale for children is a valid and reliable measurement tool for evaluating acute pain in children with cancer for the Turkish sample. The Pain Flexibility Scale can be used to determine the psychological acceptance of acute pain. In addition, cross-cultural comparative studies can be planned using scales.

      Funding

      The authors received no financial support for the research, authorship, and/or publication of this article.

      Contributors' statement

      All the authors contributed to the concept and design, acquisition and interpretation of data, drafting the article and gave final approval of the version to be published.

      Conflicts of Interests

      The authors have no funding or conflicts of interest to disclose. The authors have no conflicts of interest to disclose.

      CRediT authorship contribution statement

      Murat Bektas: Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. Aslı Akdeniz Kudubes: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing.

      Acknowledgement

      We would like to thank to all participants. This study was presented as an oral presentation at the International Health Research Congress (ICOHER'21).

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