Wing S. Wong, PhD,* Phoon P. Chen, MBBS, Yu F. Chow, MBBS, Steven Wong, MBBS, and Richard Fielding, PhD

Transcription

1 Pain Medicine 2015; 16: Wiley Periodicals, Inc. Brief Research Report The Reliability and Validity of the Cantonese Version of the Pain Treatment Satisfaction Scale (ChPTSS) in a Sample of Chinese Patients with Chronic Pain Wing S. Wong, PhD,* Phoon P. Chen, MBBS, Yu F. Chow, MBBS, Steven Wong, MBBS, and Richard Fielding, PhD *Department of Psychological Studies and Center for Psychosocial Health, The Hong Kong Institute of Education, 10 Lo Ping Road, Tai Po, Hong Kong SAR, China; Department of Anesthesiology and Operating Services, Alice Ho Miu Ling Nethersole Hospital, Tai Po, Hong Kong; Department of Anesthesiology and Operating Services, Queen Elizabeth Hospital, Kowloon, Hong Kong; Department of Anesthesiology and Operating Services, School of Public Health, University of Hong Kong, Pokfulam, Hong Kong SAR, China Reprint requests to: W.S. Wong, Department of Psychological Studies and Center for Psychosocial Health, The Hong Kong Institute of Education, 10 Lo Ping Road, Tai Po, Hong Kong SAR, China. Tel: ; Fax: ; wingwong@ied.edu.hk. Conflict of Interest: No conflict of interest declared. Abstract Objectives. The Pain Treatment Satisfaction Scale (PTSS) was developed in a Western context for evaluating patients satisfaction with pain treatment. Although the instrument was shown to possess good psychometric properties, its reliability and validity among ethnic Chinese has not been examined. This article reports the translation of the English-language version of the PTSS into Traditional Chinese Cantonese (ChPTSS) and the preliminary examination of the reliability and concurrent predictive validity of the ChPTSS. Methods. A total of 201 Chinese patients with chronic pain completed the ChPTSS, the Chronic Pain Grade questionnaire, the mental health questions of the 12-item Short Form Health Survey (SF- 12), and questions assessing sociodemographic and pain characteristics. Results. All ChPTSS scales demonstrated good internal consistency, with Cronbach s as ranging from 0.77 to 0.90, and they all correlated with two criterion measures, mental health quality life (QoL) and pain disability, in expected directions. Results of hierarchical multiple regression models showed that the ChPTSS scales predicted concurrent mental health QoL (F(6,191) , P < 0.001) and pain disability (F(6,189) , P < 0.01). Side Effects emerged as the only significant independent predictor in both models (mental health QoL: std b , P < 0.001; pain disability: std b , P < 0.01). Conclusion. Our results offer preliminary evidence for the reliability and concurrent predictive validity of the ChPTSS, which can be applied in Cantonese speaking context. Key Words. Patient Satisfaction; Pain Treatment; Cantonese Introduction The Pain Treatment Satisfaction Scale (PTSS) was developed for assessing satisfaction with pain treatment in patients having both acute and chronic pain [1]. The initial item pool of 67 items was derived based on semistructured interviews with patients with acute and chronic pain, physicians specializing in pain medicine, and nurses. The 67 items were initially grouped in seven 2316

2 Pain Treatment Satisfaction Among Chinese hypothesized domains including general, information about pain and its treatment, medical care, current pain medication, pain medication route of administration, satisfaction with pain management and care, and side effects of medication. There are also seven stand-alone items assessing respondents overall satisfaction and preference for treatment. The psychometric properties of the scale were initially examined in a sample of 200 patients with chronic (n 5 89) or acute (n 5 111) pain. Results of principal component analyses supported the hypothesized structure and identified 39 items with item-total correlations above The finalized 39 items are grouped in five dimensions: 1) Information, 2) Medical care, 3) Impact of current pain medication, 4) Side effects, and 5) Satisfaction with pain medication, with the last scale further divided into two subscales, namely, Efficacy subscale and medication characteristics subscale. The scale also demonstrated good internal consistency, with Cronbach s as ranging from 0.83 to 0.92, and good test retest reliability, with rs ranging from 0.67 to Negative correlations between the PTSS scales and pain intensity after treatment were demonstrated with rs ranging from to While there are many generic tools to assess patient satisfaction, tools that are specifically designed for the pain setting are scarce. Previous studies showed that the correlates of patient satisfaction in the pain population differ from other patient populations. For instance, in other nonchronic patient groups, symptom relief was associated with greater satisfaction [2,3] and symptom chronicity predicated patient satisfaction [4]. Among patients with chronic pain, satisfaction level, however, was high even though symptom relief was not significantly reduced [5,6]. These data suggest the needs and expectation of pain patients are very different from those of the other patient groups, and hence, generic tools to assess patient satisfaction may not be relevant. At the time this study was planned and implemented, the PTSS is the only validated instrument available. Patient satisfaction research in the Chinese setting is extremely limited. Apart from an indigenous instrument namely the 9-item Chinese Patient Satisfaction Questionnaire for assessing patient satisfaction with outpatient clinical services, no standardized instrument was available [7 10]. The PTSS was adopted in this study not only because it is psychometrically sound, it has been widely used in assessing pain treatment satisfaction in pain treatment trials [11 14] and pain management programs [15,16]. As the development and application of the instrument was in Western, English-speaking context, the applicability of the instrument in non-western settings remains unclear. In light of this, the objective of this study was to examine reliability and concurrent predictive validity of the Chinese Cantonese translation of the PTSS (ChPTSS) in a sample of Chinese patients with chronic pain. A validated Cantonese version of the PTSS would facilitate international use of the instrument and future cross-cultural research of patient satisfaction in the pain setting. The validation of the ChPTSS would also offer important data to inform clinical practice in Hong Kong and other Chinese populations, as well as in ethnically diverse countries such as North America and the United Knigdom. Method Subjects Following ethics approval, consecutive patients with chronic pain were recruited from pain clinics of two public hospitals. Patients were eligible for the study particpation if they met the following criteria: 1) 18 years of age, 2) native Cantonese speakers, 3) having no communication problems or physical conditions that will prevent the completion of the interview, 4) no confusion or cogitive impairment diagnosis in their medical record, and 5) willingness to participate in the study. Face-toface interviews were conducted by trained research assistants on eligibile patients, following written consent, while they waited for their medical consultation. Measures The PTSS The PTSS consists of 39 items assessing five aspects of satisfaction of pain treatment: 1) Information (five items; e.g., How much information would you have liked to have received about: my illness or injury, the causes of my pain,? ), 2) Medical care (eight items; e.g., It is easy to ask the medical staff questions, The medical staff provide adequate follow-up care ), 3) Impact of current pain medication (eight items; e.g., My pain medication helps me have a better outlook on life, my pain medication improves my mood ), 4) Side effects (12 items; e.g., How much were you bothered by the following: drowsiness, nausea, heartburn? ), and 5) Satisfaction with pain medication which is divided into two subscales, Efficacy (three items; e.g., How satisfied are you with each of the following: the time that it takes your pain medication to work, the duration of pain relief provided by your pain medication, etc? ) and Medication characteristics (three items; e.g., My oral pain medication is easy to swallow, My intravenous pain medication works quickly, My patch pain medication irritates my skin ) subscale. Following the response options of the original scale, except for the side effects subscale which is rated on a 6-point Likert scale (0 5 not experience; 5 5 extremely bothered), all other ChPTSS scales are rating on a 5-point Likert scale (1 5 strongly agree, 5 5 strongly disagree), with lower scores indicating higher satisfaction. The Cantonese version of the PTSS (ChPTSS) was first translated from the original by the first author (WSW). Following crosscultural adaptation procedures, the translation emphasized comprehensibility and appropriateness of the language in the Chinese cultural context. The Cantonese version was back-translated into English by a bilingual postgraduate psychology student. The English backtranslation was reviewed by a native English speaker for content equivalence between the back translation and 2317

3 Wong et al. the original version of the PTSS. Discrepancies were discussed and resolved by consensuses, and modification were made as needed, resulting in the penultimate version of the ChPTSS. A panel consisting of eight bilingual postgraduate students was asked to provide independent rating on the fluency and semantic equivalence of the Cantonese translation against the original English version of the PTSS items on a 5-point Likert scale (1 5 poor, 2 5 fair, 3 5 good, 4 5 very good, 5 5 excellent). The results of the panel assessment revealed that, except for 3 of the 39 items that obtained a modal rating of 3, all other items obtained a rating of 4 or 5, suggesting a good or excellent equivalence of the item translation. This penultimate version of the ChPTSS was then piloted in 10 Chinese patients attending a multidisciplinary clinic in Hong Kong. All participating patients indicated the instructions and items were easy to understand. Chronic Pain Severity and Disability The Chronic Pain Grade (CPG) questionnaire [17] was used to assess chronic pain severity and disability. CPG is a seven-item instrument that measures three domains of pain severity: intensity, persistence, and disability/interference. The three intensity items ask respondents to rate their current, average, and worst pain intensity on 0 10 numerical rating scales (NRS; 0 5 No pain at all ; 10 5 Pain as bad as could be ). Three CPG items assess pain interference with 1) daily activities, 2) social activities, and 3) working ability using 0 10 NRSs (0 5 No interference/change ; 10 5 Unable to carry on activities/extreme change ). Persistence is assessed in the original CPG by asking the respondent to indicate the number of days out of the past 3 months that he/she was disabled by pain. The CPG can generate a Disability Score (with higher scores indicating higher disability) and classify subjects into five hierarchical grades: Grade Zero (pain free), Grade I (low disability-low intensity), Grade II (low disability-high intensity), Grade III (high disability-moderately limiting), and Grade IV (high disability-severely limiting). The English version of the CPG possesses good psychometric properties [18] and is responsive to change in pain severity over time [19]. The underlying structure of the Chinese version of CPG demonstrated good psychometric properties, with Cronbach s as for the CPG Disability and Characteristic Intensity scales of 0.87 and 0.68 [20]. Mental Health Mental health was measured by the Medical Outcomes Study 12-item Short-Form Health Survey (SF-12, version 2) [21,22], a shorter form of SF-36, which measures the health-related quality life (QoL) [23]. The 12 questions are summarized into a physical component (QoL-Physical) score and a mental component score (QoL-Mental) using the standard scoring algorithm based on the general population of the United States [22]. The SF-12 has been translated into and validated in Hong Kong Chinese [24]. Higher scores indicate better QoL. The CPG and SF-12 were selected as criterion measure for concurrent predictive validity because of their sound psychometric properties and the availability of a validated Chinese version. Data Analysis Subject and pain characteristics, bivariate relationships between variables, and internal consistency for the ChPTSS scales were analyzed using descriptive statistics. Cronbach a > 0.60 is defined as the minimum value for acceptable internal consistency [25]. Two hierarchical multiple regression models were fitted to examine the association between ChPTSS scales and concurrent criterion variables including QoL-Mental and painassociated disability. Sociodemographic variables that were statistically significant at P < 0.05 were entered in the first block and pain variables including number of pain sites and pain duration were entered in the second block. All ChPTSS scales were entered in the last block. The dependent variables were indexed against the CPG Disability Score and QoL-Mental scores. All proportions are rounded to the nearest whole number, and analyses were performed using SPSS [26]. Results Subject Characteristics Of 212 eligible patients giving written consent and recruited, eight subsequently refused to participate in the study and three did not complete the questionnaire, leaving 201 patients in the data analyses. Table 1 shows 40% of the sample were male and the average age of the sample was 50.6 years (SD ). Over half of the sample reported a household monthly income <HK$15,000, and over 60% were married or cohabiting. About 57% had attained secondary education, whereas 72% endorsed no religious affiliation. Nearly 35% were engaged in full-time employment while the proportions of retirees and unemployed constituted 10 and 30% of the sample, respectively. Pain Characteristics The pain characteristics of the sample are reported in Table 2. The current Chinese sample had an average of 2.35 (SD ; range, 1 16) pain sites, with nearly 16% reporting six or more pain sites. The three most common pain sites were leg (44%), neck (36%), and shoulder (36%). Patients had suffered from pain for an average of 2.08 years (SD ; median 5 3; range,

4 Pain Treatment Satisfaction Among Chinese Table 1 Sociodemographic profile of the sample Table 2 Pain characteristics of the sample Sociodemographic Characteristics % Gender Male 40.0 Female 60.0 Age in year; M (SD) (10.94) Monthly household income* <HK$15, $15,000 $24, $25,000 $39, $40,000 $59, $60, Marital status Never married 25.3 Married/cohabiting 63.6 Divorced/separated 8.1 Widowed 3.0 Education level No schooling/preprimary 6.0 Primary 18.4 Secondary 57.1 Matriculation 4.1 Postsecondary 5.1 Tertiary or above 9.2 Religion No religion 71.7 Catholic 1.0 Christian 14.1 Buddhism/Daoism/Ancestor Worship 13.1 Employment status Full time 34.7 Part time 5.1 Retired 10.2 Unemployed 29.6 Housewife 15.3 Others 5.1 Note: Figures are percentages unless otherwise stated; Differences analyzed with t-test; proportional differences analyzed with chi-square tests; M: mean; SD: standard deviation; ns: P value not significant at P < *P < 0.05; **P < 0.01; *** P < * $1 U.S. 5 $7.8 HK. months 31 years), more than 30% had been suffering from pain problems for more than 5 years. The mean pain intensity scores for present, average, and worst pain were 5.38 (SD ), 6.32 (SD ), and 8.37 (SD ), respectively. The average pain interference scores were 6.59 (SD ), 6.52 (SD ), and 6.84 (SD ) for daily activities, social activities, and Pain Characteristics % Number of pain sites; M (SD) 2.35 (1.04) Pain sites Leg 43.8 Neck 36.3 Shoulder 35.8 Hand/arm 25.4 Knee 20.4 Head 19.9 Upper back 18.9 Others 15.4 Pelvis 14.9 Lower back 11.4 Face 8.0 Joint 6.0 Chest 5.5 Muscle 4.5 Stomach 3.0 Abdomen 2.5 Pain duration (years); M (SD) 2.08 (0.96) 3 months 2 years 32.5 >2 years 5 years 37.0 >5 years 10 years 21.0 >10 years 9.5 Pain intensity*; M (SD) Present pain 5.38 (2.39) Average pain 6.32 (1.91) Worst pain 8.37 (1.75) Pain interference ; M (SD) Daily activities 6.59 (2.45) Social activities 6.52 (2.95) Working ability 6.84 (2.87) Pain-associated disability (days); M (SD) (41.7) Chronic Pain Grade classification Grade I 8.6 Grade II 28.3 Grade III 25.8 Grade IV 37.4 Mental health QoL ; M (SD) (12.18) Note: The pain intensity and pain interference scores were drawn from individual items of the Chronic Pain Grade questionnaire; QoL: Quality of Life. * Scores range from 0 to 10; higher scores indicate higher intensity of pain. Scores range from 0 to 10; higher scores indicate higher level of interference. Grade I: low disability-low intensity; Grade II: low disabilityhigh intensity; Grade III: high disability-moderately limiting; Grade IV: high disability-severely limiting. Indexed by SF12-Mental Health component score, with higher scores indicating better mental health QoL. 2319

5 Wong et al. Table 3 Internal consistency, means (standard deviations), and correlations between the ChPTSS scales Pearson s Correlation Pain Disability QoL- Mental Score Range Mean (SD) Cronbach a No. of Items ChPTSS Scale 1. Information about pain and its treatment (0.90) * 2. Medical care (0.63) Impact of current pain medication (0.88) * Side effects of the medication (0.91) * 5. Satisfaction with current pain medication (0.72) * 0.17* Medication characteristics subscale (0.79) Medication efficacy subscale (0.90) Note: All items are rated on a 0 5 scale of agreement. * P < P < P < Both are subscales of satisfaction with current pain medication. working ability, respectively. The current sample reported an average of days (SD ; range, 0 90 days) of pain-associated disability. CPG classified 63% of the current sample as Grade III or above, suggesting high disability-moderately limiting to high disability-severely limiting. The mean score of QoL- Mental was 34.5 (SD ). Internal consistency, means, standard deviations, and correlations of ChPTSS scales with concurrent measures As presented in Table 3, the Cronbach as of ChPTSS scales ranged from 0.77 to 0.90, suggesting moderately-high to high internal consistency. Of the seven scales/subscales, the mean score of Impact of current pain medication subscale was the highest (=3.32, SD ), whereas Medical Care subscale was the lowest at 2.14 (SD ). Excepting the Medical Care (r , P < 0.01) and Side Effects subscales (r , P < 0.001), Information about pain and its treatment subscale did not correlate significantly (P > 0.05) with other ChPTSS scales. All other ChPTSS scales demonstrated significant positive correlations with each other, with rs ranging from 0.19 to 0.87 (P < 0.05), except the correlation between Medical Characteristics subscale and Impact of current pain medication subscale (r , ns). All ChPTSS scales were correlated with Pain Disability scores in a positive direction. QoL-Mental was correlated with all ChPTSS scales in a negative direction. Multivariate prediction of concurrent pain adjustment measures from the ChPTSS scales The results of hierarchical multiple regression analyses are reported in Table 4. After adjustment for effects of sociodemographic and pain variables, ChPTSS scales accounted for 13% of the total variance in the QoL- Mental model (F(6,191) , P < 0.001), with Side Effects scores emerging as an independent predictor of QoL-Mental score (std b , P < 0.001). As for the Pain Disability model, ChPTSS scales contributed significantly in explaining 10% of the total variance (F(6,189) , P < 0.01). Of the six ChPTSS scales, the Side Effects scale again emerged as an independent predictor of Pain Disability scores (std b , P < 0.01). Discussion This article reports the translation of the PTSS into traditional Chinese language (ChPTSS) and the psychometric properties of the ChPTSS in a sample of Chinese patients with chronic pain. The reliability and concurrent predictive validity of the ChPTSS were supported based on moderate to moderately high Cronbach s as of the ChPTSS scales. 2320

6 Pain Treatment Satisfaction Among Chinese Table 4 Hierarchical multiple regression analyses predicting concurrent QoL and pain disability with ChPTSS scales Criterion Variable Step Predictor Std b SE 95% CI R 2 DR 2 DF QoL-Mental 1 Sociodemographic variables * Occupation: Full-time , Pain variables Pain duration 0.05* , 2.43 No of pain site , ChPTSS scales *** Information about pain and its treatment , 0.49 Medical care , 0.44 Impact of current medication , 0.14 Side effects of medication 20.31*** , Medication characteristics subscale , 1.03 Medication efficacy subscale , 0.28 QoL-Physical 1 Sociodemographic variables *** Income , 0.01 Occupation: Full-time , 3.51 Education level , Pain variables ** Pain duration , 0.01 No of pain site 0.16* , ChPTSS scales ** Information about pain and its treatment , 0.33 Medical care , 0.90 Impact of current medication , 0.64 Side effects of medication 20.25** , 0.92 Medication characteristics subscale , 2.44 Medication efficacy subscale , 1.08 Note: Pain disability was indexed by the CPG Disability Score with scores ranging from 0 to 100 and higher scores indicating greater level of disability. QoL-Mental was indexed by the mental health component score of SF12. ChPTSS was indexed by the Chinese version of Pain Treatment Satisfaction Scale with higher scores indicating higher dissatisfaction. Std b 5 standardized beta coefficient; SE 5 standard error; CI 5 confidence interval; D 5 change. Of the seven ChPTSS scales, impact of current pain mediation obtained the highest mean scores, suggesting that this was the least satisfactory aspect of pain treatment in this Chinese sample. This might be partly due to the fact that the items in this scale assess the psychosocial impact of pain medication. As the average pain duration of the current sample was around 2 years and median duration 3 years, which is relatively short, patients might, therefore, be still adapting to their chronic conditions both psychologically and socially. Conversely, medical care obtained the lowest mean scores among the seven ChPTSS scales, suggesting that the care and services provided by the medical staff at multidisciplinary pain clinics were the most satisfactory aspect of pain treatment in this sample. Specialist services for chronic pain in Hong Kong are limited to eight multidisciplinary pain clinics in public hospitals. Most patients with chronic pain are managed by orthopaedics specialist. One major difference between orthopaedics and multidisciplinary pain services is that patients treated at orthopaedics clinics will receive clinical assessment only, whereas patients attending multidisciplinary pain clinics will receive a thorough clinical and psychological assessment conducted by specialists from different disciplines [27]. Yet, the heavy patient load in multidisciplinary pain clinics means patients face long queues for psychological assessment and services there. Our findings, therefore, identify psychological services as one major area to target for improving the quality of health care delivery in Hong Kong multidisciplinary pain clinics. Consistent with a previous report [1], the ChPTSS scales possessed good internal consistency, with Cronbach s as ranging from 0.77 to Except for the relationship between medication characteristics and efficacy (r ), low correlations between PTSS scales (0.52) were found in the original study [1]. Similar results are obtained in the current Chinese sample. Except for the moderately high correlations between 2321

7 Wong et al. Satisfaction with current pain medication and its two subscales (rs 0.82, P < 0.001), the correlations between other ChPTSS scales were low, ranging from 0.06 to These findings suggest that the seven dimensions of pain treatment are quite independent. Patients might be highly satisfied with one aspect of pain treatment, but dissatisfied with other aspects. Of the two concurrent criterion measures assessed, ChPTSS scales appear to demonstrate more significant correlations with Pain Disability because five of the ChPTSS scales were significantly correlated with Pain Disability (P < 0.05). Yet, the direction of relationship with both criterion measures was in the expected direction lower ChPTSS (which indicates higher satisfaction) scores trended with better mental QoL and less pain disability. Our findings add to the original validation report [1] by offering preliminary evidence for the concurrent predictive validity of the ChPTSS. After controlling for sociodemographic and pain variables, ChPTSS demonstrated significant contribution to the prediction of concurrent mental health QoL and pain disability. The amount of unique variance explained by ChPTSS scales in the mental health QoL model, at 13%, was much higher than that associated with sociodemographic and pain variables (3 and 2%, respectively), suggesting that patients satisfaction with pain treatment is much more important that background factors like income, education level, pain duration and number of pain sites, in affecting their mental health QoL. Side Effects consistently offered significant independent prediction of concurrent mental health QoL and pain disability. These findings point to the possible side effects of pain medication being the areas with which patients are most concerned and which significantly influence patients evaluation of pain treatment satisfaction, or possibly that dissatisfied patients tend to blame their medication for perceived functional impairments or inadequacies. Nonetheless, the psychometric properties of the ChPTSS reported in this article should be taken as tentative. As the ChPTSS was translated and validated within a Cantonese-speaking context, the extent to which the ChPTSS can be generalized to other Chinese-speaking populations speaking Mandarin/ Putonghua is unknown. Further research to evaluate the ChPTSS in other Chinese populations speaking other Chinese dialects is, therefore, warranted. Also, because this study s findings are based on cross-sectional data, the causal relationships between pain treatment satisfaction and pain-associated adjustment outcomes cannot be determined. Future studies employing longitudinal, prospective designs with other criterion measures could help address these limitations. As data for this study were collected from pain patients attending multidisciplinary pain services, the findings, we report may not be applicable to other pain patients managed by other medical specialists such as psychiatrists, orthopedic surgeons, neurologist, or neurosurgeons. Under the current public service model for pain management in Hong Kong, if pain patients attending (nonpain) specialist clinics do not show improvement in 1 2 years, they are referred to a specialist pain clinic. Specialist clinic patients likely have different expectations of pain treatment and medical care to those attending multidisciplinary pain clinic services [28]. As patient satisfaction is greatly grounded in expectation, pain treatment satisfaction of these subpopulation of pain patients could be different. 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