Validation Study of the Korean Version of the M. D. Anderson Symptom Inventory

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Journal of Pain and Symptom Management

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Original Article

Validation Study of the Korean Version of the M. D. Anderson Symptom Inventory Young Ho Yun, MD, PhD, Tito R. Mendoza, PhD, Im Ok Kang, RN, PhD, Chang Hoon You, MPH, Ju Won Roh, MD, PhD, Chang Geol Lee, MD, Won Sup Lee, MD, PhD, Keun Seok Lee, MD, Soo-Mee Bang, MD, PhD, Sang Min Park, MD, Charles S. Cleeland, PhD, and Xin Shelley Wang, MD Quality of Cancer Care Branch (Y.H.Y., I.O.K., C.H.Y., S.M.P.), Uterine Cancer Branch (J.W.R.), and Breast Cancer Branch (K.S.L.), Research Institute and Hospital, National Cancer Center, Goyang, Gyeonggi, Korea; Department of Symptom Research (T.R.M., C.S.C., X.S.W.), The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA; Department of Radiation Oncology (C.G.L.), Yonsei University College of Medicine, Yonsei Cancer Center, Seoul, Korea; Department of Internal Medicine (W.S.L.), Gyeong-Sang National University Hospital, Jinju, Korea; and Department of Internal Medicine (S.M.B.), Gachon Medical School, Ghil Medical Center, Incheon, Korea

Abstract This study aimed to evaluate the Korean version of the M. D. Anderson Symptom Inventory (MDASI-K) as a tool for assessing multiple symptoms in Korean cancer patients. Participants (178 cancer patients and 178 age and sex-matched community-dwelling adults) completed the MDASI-K and the Korean version of the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30. The MDASI-K exhibited substantial reliability and validity. Cronbach a coefficients were 0.91 and 0.93 in the cancer patients, and 0.96 and 0.96 in the normal group for both symptom and interference, respectively. MDASI-K summary scores correlated significantly with those of the EORTC QLQ-C30. Discriminant validity of the MDASI-K was demonstrated by its ability to clearly distinguish significant differences within different Eastern Cooperative Oncology Group performance statuses and those between the patient and normal groups in the mean scores of both symptom and interference. The MDASI-K is a valid and reliable measure for assessing multiple symptoms in Korean cancer patients. J Pain Symptom Manage 2006;31:345--352. Ó 2006 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved. Key Words Cancer, symptom, validation, Korean, MDASI

This work was supported by National Cancer Center Grant 0110030. Address correspondence to: Young Ho Yun, MD, PhD, Quality of Cancer Care Branch, Research Institute, National Cancer Center, 809, Madu-dong, Ilsan-gu, Goyang-si, Gyeonggi-do, 411-769, Korea. E-mail: [email protected]. Accepted for publication: July 25, 2005. Ó 2006 U.S. Cancer Pain Relief Committee Published by Elsevier Inc. All rights reserved.

Introduction Cancer patients suffer from a variety of symptoms that significantly impair their functional ability and quality of life (QOL).1,2 These multiple symptoms can arise from the disease itself or from the toxicities of its treatment. In one study of newly diagnosed (untreated) cancer 0885-3924/06/$--see front matter doi:10.1016/j.jpainsymman.2005.07.013

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patients, 38% experienced moderate to severe fatigue, 30% experienced insomnia, and 23% experienced pain.3 Cancer treatments, such as chemotherapy and radiotherapy, are also known to cause a variety of symptoms. Cleeland et al., in a study of cancer patients undergoing active treatment in the United States, found that more than 20% of patients reported severe symptoms, including fatigue (38%), worrying (26%), lack of appetite (25%), disturbed sleep (24%), and dry mouth (24%). Studies among the Korean cancer population have revealed similar struggles with multiple symptoms, particularly anorexia (52%), pain (44.8%), depression (40%), and fatigue (68%).4--7 Despite these data, the efficacy of current symptom management in Korea has not been well studied. The optimal management of these symptoms is dependent on frequent, accurate symptom assessment and good communication between cancer patients and health care professionals. Symptoms are typically measured by rating scales, such as the Symptom Distress Scale,8 the Memorial Symptom Assessment Scale,9 the Rotterdam Symptom Checklist,10 and the Edmonton Symptom Assessment System.11 A more recent scale, the M. D. Anderson Symptom Inventory,12 was developed by Dr. Charles Cleeland and colleagues13,14 in the Department of Symptom Research at The University of Texas M. D. Anderson Cancer Center based on their research into pain and fatigue. The MDASI has several advantages over the aforementioned scales, in that it contains the most frequently reported and distressing symptoms, includes interference items, is easy to administer, and is easily translated into other languages. The goal of this study was to validate the Korean version of the MDASI (MDASI-K) (Appendix) and to examine symptoms related to cancer and its treatment in Korea. We used a Korean version of the European Organization for Research and Treatment (EORTC) QLQ-C30, a quality-of-life questionnaire frequently used with cancer patients, for comparative measurement.15

Methods Patients, Normal Subjects, and Data Collection Our study sample included both normal community-dwelling adults and adult cancer

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patients being treated in five Korean hospitals. The patients had a variety of cancer types, had undergone various treatments, and had different symptom severity levels. To participate in our study, patients were required to be older than 18, have a pathological diagnosis of cancer, give informed consent to participate in the study, and be able to understand and complete the questionnaires. The communitydwelling subjects were recruited from individuals who had visited the Department of Cancer Prevention in the National Cancer Center, Korea, for cancer screening. They were matched to the patient sample for sex and age, and met all eligibility requirements except having a pathological diagnosis of cancer. The study was approved by the Institutional Review Boards of the National Cancer Center, Korea and M. D. Anderson Cancer Center, Houston. The cancer patients completed the self-administered questionnaires either at an outpatient clinic visit or during their hospitalization. Community-dwelling adults completed the questionnaires at their screening visit.

Measures The M. D. Anderson Symptom Inventory. The MDASI includes a 13-item symptom scale and a 6-item interference scale. The first 13 items describe the patient’s symptoms during the last 24 hours, with 0 being ‘‘not at all’’ and 10 being ‘‘as bad as you can imagine.’’ The last six items assess how much the symptoms interfered with various aspects of the patient’s life during the past 24 hours: general activity, mood, walking ability, normal work (including housework and work outside the home), relationships with others, and enjoyment of life, with 0 being ‘‘does not interfere’’ and 10 being ‘‘completely interferes.’’ The validity and reliability of the MDASI have been established.12 The Korean version of MDASI was developed using a forward-backward translation process. The items were first translated into Korean by one translator whose native language was Korean, and then back-translated into English by a second translator whose native language was English and who had not seen the original English version. Bilingual fluency was required of both translators to complete the translation. Next, the English back-translated items were compared with the

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The Korean M. D. Anderson Symptom Inventory

originals. If a back-translated item did not agree with the original, the first translator performed a second translation that was again back-translated by the second translator. This process was repeated until agreement was reached. European Organization for Research and Treatment of Cancer QLQ-C30 (version 3.0). The EORTC QLQ-C30 is a 30-item cancer-specific questionnaire for assessing the health-related QOL of cancer patients. The questionnaire incorporates five functional scales (physical, role, cognitive, emotional, and social), three symptom scales (fatigue, pain, and nausea and vomiting), a global health and QOL scale, and single items for assessing other symptoms commonly reported by cancer patients (e.g., dyspnea, appetite loss, sleep disturbance, constipation, and diarrhea) and the perceived financial impact of the disease and treatment.15 The Korean version of the EORTC QLQ-C30 has been validated.16

Statistical Analysis We used descriptive statistics to describe how patients rated symptom severity and interference with function. Reliability. Reliability was assessed by calculating the Cronbach a coefficient,17 a measure of the internal consistency of responses. A low a value suggests that some items either have very high variability or that the items are not all measuring the same thing. As recommended, we sought an a of 0.70 or greater as the minimum criterion for internal consistency.18 Validity. Multitrait scaling analysis was used to examine the extent to which the items of the MDASI-K could be combined into the symptom and interference scales. Item convergent validity of the MDASI-K items was evaluated by examining item to dimension correlations. Item convergent validity would be present if the correlation between an item and its dimension (i.e. item to own-dimension correlation) was $0.4.19 A definite scaling error was assumed if the correlation of an item with another scale exceeded the correlation with its own scale or was above 0.4. Construct validity was determined using a principal-axis factor analysis with a varimax rotation, which

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reproduced the same factor-loading pattern seen in the original English MDASI.20 Concurrent validity was evaluated by calculating the Pearson product moment correlation coefficient between the MDASI-K and the EORTC QLQ-C30 symptom subscale. Two methods were used to evaluate the discriminant validity of the MDASI-K. First, we used a comparison of patients and normal subjects to evaluate the MDASI-K’s ability to discriminate between groups. We used the t test to evaluate statistically significant differences in subscale scores between patients and normal subjects. Second, we compared the MDASI-K scores of patients stratified by Eastern Cooperative Oncology Group Performance Status (ECOG PS). We hypothesized that patients with poor performance status would have increased levels of fatigue and interference. We used a nonparametric analysis (Wilcoxon rank sum test) with subjects grouped by performance status (ECOG PS ¼ 0,1,2 and ECOG PS ¼ 3,4) to evaluate between-group differences. For these analyses, we set the significance level at P < 0.05. All statistical tests were twotailed. We used SAS statistical software, version 8.1.

Results Patient Characteristics The demographic and clinical characteristics of the sample are shown in Table 1. The mean age of the patient group was 51.1 (SD ¼ 11.3) years, most (79%) were married, and 67% had at least a high school education. The sociodemographic characteristics of the normal group were similar to those of the patient group. About 60% of the cancer patients were receiving some form of chemotherapy. Approximately 21% of patients had local disease and 56% had metastatic cancer. Nineteen percent of the cancer patients had poor functional status (an ECOG PS score of 2 or higher).

Missing Response Rate There were no missing responses to the first question of the MDASI-K. A total of 16 responses were missing for the other nine questions combined, three responses from the patient group and 13 from the normal group,

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Table 1 Sociodemographic and Clinical Characteristics of the Study Sample Patients (n ¼ 178) Characteristics Age Mean (SD) Gender Female

Normal (n ¼ 178)

n

%

n

%

51.1

(11.3)

50.3

(11.0)

71

39.9

71

39.9

Education More than high school

118

33.7

155

44.3

Occupation Employed full time Homemaker Retired Disabled due to illness Other

23 56 21 39 33

13.4 32.6 12.2 22.7 19.2

85 41 19 0 28

49.1 23.7 11.0 0.0 16.2

162

91.5

Marital status Married

139

79.0

Cancer site Lung Head and neck Cervix Stomach Colon/rectum Leukemia Others

42 21 18 18 17 11 51

11.8 5.9 5.1 5.1 4.7 3.1 14.3

Disease status Metastatic

98

55.7

8 78 13 28

4.5 43.8 7.3 15.7

11

6.2

1

0.6

39

21.9

39 105

21.9 59.0

24

13.5

8

4.5

2

1.1

Treatment within a month Radiotherapy Chemotherapy Surgery Radiotherapy and chemotherapy Radiotherapy and surgery Chemotherapy and surgery No treatment ECOG PS 0 ¼ Fully active 1 ¼ Restricted but ambulatory 2 ¼ Ambulatory, capable of self-care 3 ¼ Capable of only limited self-care 4 ¼ Completely disabled

SD ¼ standard deviation; ECOG PS ¼ Eastern Cooperative Oncology Group Performance Status.

resulting in a missing-data rate for the patient group of 0.3% of 3,382 total data points (178 patients answering 19 items), and 1.1% of the same number of data points for the normal group. Because all individuals responded to a majority of the items, all of the collected data were included in this analysis.

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Reliability For both patient and normal groups, all Cronbach’s a values for multi-item scales far exceeded Nunnally’s 0.70 criterion for internal consistency and reliability: Cronbach’s a values for the patient group were 0.91 for symptom items and 0.93 for interference items; Cronbach a values for the normal group were 0.96 for symptom items and 0.96 for interference items.

Multitrait Scaling A multitrait scaling analysis, based on the examination of correlation coefficients among the items and scales, was conducted to test for item convergent and discriminant validity. The multitrait scaling analysis of the MDASI-K showed that all items and their dimension correlation coefficients were above 0.40.19 In terms of item discriminant validity, no scaling errors were found. The analysis data confirmed that all the scales met the recommended psychometric standards.

Construct Validity Construct validity was confirmed by factor analysis. MDASI-K factor-loading patterns for patient and normal groups are shown in Table 2. In both groups, symptom items loaded on the first factor and interference items loaded on the second factor, confirming a 2-factor solution for the MDASI-K similar to the original MDASI. In the patient group, eigenvalues were 9.85 for the first factor and 1.79 for the second factor. The first factors of both patient and normal groups explained 52% and 65% of the variability in the data, respectively. The factor loading of an analysis using only symptom items for both patient and normal groups explained 56% and 67% of the variability, respectively.

Concurrent Validity The concurrent validity of the MDASI-K in the patient group was demonstrated by calculating correlations between MDASI-K scores and EORTC QLQ-C30 subscale scores. Table 3 shows the correlations between MDASI-K summary scores (symptom and interference) and each EORTC QLQ-C30 score. On the whole, the symptom scales of the MDASI-K correlated better with the symptom scales of the EORTC

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Table 2 Factor Analysis with Pattern Matrix of MDASI Items in Cancer Patients and Normal Group Cancer Patient Group (n ¼ 178) Including all items

Normal Group (n ¼ 178) Including all items

Factor 1

Factor 2

Including only symptom items

Factor 1

Factor 2

Including only symptom items

Symptom Pain Fatigue Nausea Sleep disturbance Distress Shortness of breath Remembering Appetite Drowsy Dry mouth Sad Vomiting Numbness

0.73 0.71 0.82 0.74 0.69 0.66 0.59 0.74 0.49 0.64 0.59 0.82 0.44

0.31 0.39 0.13 0.27 0.44 0.33 0.31 0.30 0.37 0.31 0.38 0.14 0.21

0.77 0.79 0.77 0.77 0.81 0.74 0.67 0.80 0.61 0.71 0.59 0.79 0.73

0.65 0.57 0.73 0.78 0.77 0.81 0.80 0.65 0.70 0.74 0.77 0.71 0.76

0.51 0.50 0.36 0.30 0.42 0.29 0.24 0.41 0.40 0.29 0.34 0.28 0.36

0.81 0.76 0.79 0.82 0.88 0.87 0.82 0.76 0.82 0.81 0.83 0.75 0.82

Interference General activity Mood Work Relation Walking Enjoyment

0.39 0.38 0.27 0.21 0.33 0.27

0.82 0.80 0.87 0.83 0.75 0.78

0.38 0.41 0.43 0.40 0.21 0.36

0.86 0.86 0.83 0.84 0.81 0.79

Eigenvalue Percent variance explained

9.85 52%

1.79 9%

12.40 65%

1.50 8%

Scales/Items

QLQ-C30, while the interference scales of MDASI-K correlated better with the function scales of EORTC QLQ-C30. Almost all MDASI-K summary scores were significantly correlated with EORTC QLQ-C30 function and symptom scores in both patient and normal groups.

Discriminant Validity Discriminant validity was examined in the patient group by comparing the MDASI-K item scores of groups stratified by ECOG PS. As expected, patients with severely impaired performance status (2 or higher) reported significantly higher MDASI-K median scores with the exception of ‘‘sad’’ item than did those having a good status (P < 0.01). We also investigated differences in MDASI-K scores between the patient and normal groups, anticipating that the cancer patients would have higher levels of symptom severity and interference. As expected, we found significant differences between the patient and normal groups in the median scores of both symptom and interference (P < 0.001).

7.28 56%

8.66 67%

Discussion Our investigation of the reliability and validity of the Korean version of the M. D. Anderson Symptom Inventory demonstrated that the MDASI-K is a valid and practical measure for assessing multiple symptoms in Korean cancer patients. Of particular note is the scale’s practicality. Cancer patients, especially those who need symptom control, are often too ill to complete long or complicated questionnaires. The number of missing answers to this questionnaire was negligible, evidencing that the scale is easy to administer and the quantity of items is not burdensome. The simplicity and familiarity of the MDASI-K’s 0--10 numerical rating scale likely increases its ease of use. Factor analysis of symptom items only showed a one-dimensional structure, in contrast with the two-dimensional structure found in the Japanese and US MDASI validation studies. We believe that these differences are indicative of the MDASI’s overall ability to handle cultural variances. The factor loading of an analysis using only symptom items explained 52% and 65%

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Table 3 Correlation Between the MDASI Scores and EORTC QLQ-C30 Scores in Cancer Patients and the Normal Group EORTC QLQ-C30 Function Scores MDASI Summary Score

Global Health

Physical Function

Role Function

Emotional Function

Cognitive Function

Social Function

Financial Problem

Symptoms Patient group Normal group


0.44a
0.34a


0.52a
0.36a


0.53a
0.40a


0.57a
0.54a


0.57a
0.20a


0.46a
0.41a

0.45a 0.19b

Interference Patient group Normal group


0.54a
0.45a


0.61a
0.49a


0.65a
0.45a


0.67a
0.55a


0.54a
0.24a


0.55a
0.42a

0.46a 0.24a

EORTC QLQ-C30 Symptom Scores Pain

Fatigue

Nausea/Vomiting

Insomnia

Dyspnea

Appetite Loss

Constipation

Diarrhea

Symptoms Patient group Normal group

0.60a 0.32a

0.57a 0.47a

0.57a 0.46a

0.46a 0.30a

0.41a 0.41a

0.54a 0.30a

0.26a 0.26a

0.31a 0.20a

Interference Patient group Normal group

0.56a 0.47a

0.63a 0.54a

0.35a 0.36a

0.46a 0.39a

0.41a 0.35a

0.38a 0.31a

0.16b 0.27a

0.29a 0.11

a b

P < 0.01. P < 0.05.

of the variability in the patient and normal groups, respectively. In addition, the factor loading using only symptom items was higher than that using both symptom and interference items. This finding showed that MDASI-K was a well-represented explanation of the variability of patients’ symptoms and interference. As with all validation studies, ours has important limitations that should be considered. First, our study was not conducted as a comparison of the level of change of severity and interference in cancer patients. Second, we did not consider information about previous treatment or medication. Therefore, this result may not represent patients’ symptom levels in clinical practice. Forthcoming investigations should consider these limitations, and longitudinal studies are needed to evaluate the responsiveness over time. This is the first study of symptom prevalence in the Korean cancer patients. Our findings showed that these patients suffer from various symptoms, such as distress, fatigue, and numbness, indicating an urgent need for symptom management. The MDASI-K includes symptoms that should be routinely assessed in Korean cancer patients, given that the severity of the questionnaire’s symptom items clearly influences the severity of the interference scores.

In conclusion, our study demonstrated that the Korean version of the MDASI is valid, reliable, and cross-culturally sensitive for use with Korean cancer patients. Use of the MDASI-K could contribute significantly to improved symptom management in Korea, benefiting both cancer patients and those who care for them.

Acknowledgments This work was supported by National Cancer Center Grant 0110030. The authors sincerely thank the cancer patients and the control group members who cooperated so willingly.

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4. Heo DS, Yun YH, Kim HS, et al. Inappropriate care of oncologic emergency in Korea. Korean J Hospice Palliat Care 1998;1:14--22.

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