BioMed Research International
Volume 2018 (2018), Article ID 4329751, 15 pages
https://doi.org/10.1155/2018/4329751

Research Article

Adaptation and Validation of the Malay Version of the Osteoarthritis Knee and Hip Quality of Life Questionnaire among Knee Osteoarthritis Patients

Azidah Abdul Kadir,¹ Mohd Faizal Mohd Arif,¹ Azlina Ishak,¹ Intan Idiana Hassan,² and Norhayati Mohd Noor¹

¹Department of Family Medicine, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia
²Department of Nursing, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia

Correspondence should be addressed to Azlina Ishak; drzalinakk@usm.my

Received 25 October 2017; Revised 16 January 2018; Accepted 13 February 2018; Published 31 May 2018

Academic Editor: Alberto Raggi

Copyright © 2018 Azidah Abdul Kadir et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

Objective. To adapt and validate the Malay version of Osteoarthritis Knee and Hip Quality of Life (OAKHQOL) questionnaire. Design. The OAKHQOL was adapted into Malay version using forward-backward translation methodology. It was then validated in a cross-sectional study of 191 patients with knee osteoarthritis (OA). Patients completed the OAKHQOL and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. Confirmatory analysis, reliability analysis, and Pearson correlation test were performed. Results. The new five-factor model of 28 items demonstrated an acceptable level of goodness of fit (comparative fit index = 0.915, Tucker-Lewis index = 0.905, incremental fit index = 0.916, chi-squared/degree of freedom = 1.953, and root mean square error of approximation = 0.071), signifying a fit model. The Cronbach’s alpha value and the composite reliability of each construct ranged from 0.865 to 0.933 and 0.819 to 0.921, respectively. The Pearson correlation coefficient between the OAKHQOL and the WOMAC showed adequate criterion validity. Known groups validity showed statistical difference in body mass index in physical activity, mental health, and pain construct. The pain domain was statistically different between the age groups. Conclusion. The Malay version OAKHQOL questionnaire is a valid and reliable instrument to assess health-related quality of life in knee OA patients.

1. Introduction

Osteoarthritis (OA) is the most common disease of joints in adults around the world [1, 2]. Due to its chronicity in nature, it is the major cause of pain and disability. OA may affect not only physical functioning, but also mental health (anxiety and depression), sleep, work ability, interpersonal interactions, self-esteem, quality of life, sexuality, and participation [3, 4].

There are few validated instruments used in studies to assess health-related QOL in patients with OA specifically. The Medical Outcomes Study Short-Form 36 (SF36), which has been widely applied to assess QOL, is not disease-specific to OA and was found to have low response rate in population more than 65 years of age [5]. The Lequesne index and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) questionnaire, which are more disease-specific, are able to measure only pain and function but not the other domains of QOL such as mental, social, and sexual domains [6, 7]. It was suggested that the SF-36 and WOMAC should be used in combination [8]; however, they may still fail to capture specific QOL aspects related to hip or knee osteoarthritis. Knee Injury and Osteoarthritis Outcome Score (KOOS) is another questionnaire but its assessment is not limited to quality of life because it includes pain, other symptoms, activity of daily living, sports, and recreational activity measurements [9]. Thus, the Osteoarthritis Knee and Hip Quality of Life (OAKHQOL) scale questionnaire was developed and validated to measure the impact of specifically knee and hip osteoarthritis on the patient’s QOL.

The OAKHQOL is a specific tool to measure QOL in knee and hip OA as it takes into account specific themes that are exclusive to the QOL of patients with knee and hip OA (social support, sleep, side effects of drugs, plans for the future, embarrassment to be seen by people, use of public transport, difficulty in moving after staying in the same position, and sexuality) [10]. It has 43 items which fall into five domains: physical activity, pain, mental health, social functioning, and social support. Evaluation of the OAKHQOL has shown the reliability of the five domains to be satisfactory (interclass correlation coefficients: 0.70–0.85), the construct validity to be adequate (Spearman correlation coefficients: 0.43–0.75), and the discrimination to be satisfactory [10].

Confirmatory factor analysis (CFA) is a theory-testing model as opposed to exploratory factor analysis (EFA) which is a theory-generating method [11]. CFA is a type of structural equation modeling (SEM) that specifically deals with measurement models, that is, the relationships between observed measures or indicators and latent variables or factors [12, 13]. It is powerful because it provides explicit hypothesis testing for factor analytic problems.

Assessing the QOL among knee OA patients is important to ensure holistic care for the patient. Despite this, the reliability and validity of the OAKHQOL in the Malaysian context have not been established. The need for a validated questionnaire suitable to the local population based on the language is very important as it is more accurate to illustrate the real impact of the disease on the patient’s QOL. Hence, this study aimed to determine the psychometric properties of the Malay version of the OAKHQOL among knee OA patients.

2. Materials and Methods

A cross-sectional study was conducted among 191 patients diagnosed with knee OA between February and August 2014 at the Outpatient Clinic, Universiti Sains Malaysia Hospital, a tertiary teaching hospital in Malaysia. A total of 210 patients were invited, and only 191 patients fulfilled the inclusion and exclusion criteria and were recruited in the study, which give the response rate of 90%. Patients with unilateral or bilateral knee osteoarthritis diagnosed according to the clinical and radiological criteria of the American College of Rheumatology (knee pain and radiographic osteophytes plus at least one of three symptoms/signs), aged more than 50 years, who experienced morning stiffness of less than 30 minutes and crepitus on active motion, and who were able to read in the Malay language were included.

Convenience sampling was applied, and written informed consent was taken. Patients were asked to fill out the Malay version OAKHQOL (Table 7) and the validated Malay Version WOMAC. Sociodemographic data (age, gender, education, and race) and knee OA history were taken. Body mass index (BMI) measurements and weight-bearing anterior-posterior view X-rays of both knees were taken. The participants took about 15 minutes to complete both questionnaires. They also did not have to pay for their participation in the study.

Sample size was determined based on Hair et al. (2010). The minimum sample size required for five or less constructs was 100 samples [14].

2.1. OAKHQOL Questionnaire

This questionnaire was developed by Rat et al. to assess quality of life in knee and hip OA patients [10, 15], specifically to assess health-related quality of life (HRQOL) [10]. The concept of this questionnaire was based on the World Health Organization (WHO) definition of QOL. This is a self-administered questionnaire. The original questionnaire was developed in French and later in English [15]. It was shown to capture patients’ perceptions of their disease, and it possesses the necessary psychometric properties of validity and reliability for use in clinical trials and observational studies [10, 15].

In the original validation study, four factors were identified in the exploratory factor analysis based on scree plot and Eigen values. These factors were physical activities (19 items), mental health (14 items), social support (four items), and social functioning (three items). The pain factor (four items) was found to have loaded on the physical and mental health factors. However, based on expert opinions, the pain factor was included as an individual dimension. Therefore, the final English version of OAKHQOL consists of 43 items divided into five dimensions: physical activity, mental health, pain, social support, and social functioning as well as three additional items [10]. The three additional items are relationship, sexual activity, and professional life. The five dimensions (40 items) (Table 8) and three additional items are intended to be used separately. The three additional items are independent items and were not included in the analysis. Each item in the five dimensions is measured on a numerical rating scale from 0 to 10. The final scores were the mean of scores of all the items in respective domains that ranged between 0 to 10 [10].

2.2. Adaptation of the OAKHQOL Questionnaire

Forward and backward translation was carried out by a group of panelists consisting of family medicine specialists, physicians, linguists, and bilingual laymen. Modifications were made, and content validity was checked. The revised version was tested on 20 patients for face validity. These patients were excluded from the psychometric analysis.

2.3. WOMAC

WOMAC is a disease-specific, self-administered health status measure that is widely used to assess the symptoms and physical disability for people with hip and/or knee OA [16, 17]. It is widely used in OA research especially to evaluate clinical outcome measures as a result of treatment intervention [18]. The WOMAC measures total pain score, total stiffness score, and total physical functioning score. The original index consists of 24 questions (five questions for pain, two questions for stiffness, and 17 questions for physical function). It has been validated in Bahasa, Malaysia [16]. This questionnaire is available in a Likert version rated on an ordinal scale of 0 to 4 and also as a visual analog scale (VAS) [16]. In this study, a VAS version was used.

2.4. Statistical Analysis

Confirmatory factor analysis (CFA), reliability analysis, and Pearson correlation test were performed to assess the psychometric properties using SPSS version 22.0 and Analysis of Moment Structure (AMOS) software version 21.0. On preliminary data screening, cases with incomplete response were removed from data. Further assessment of normality and outliers was performed on the factor scores based on the critical ratio (i.e., for skewness and kurtosis to their standard error) and the Mahalanobis distance. Mahalanobis distance was used to identify the outliers by using AMOS software. It computes and tabulates the distance of every data from the center of all data distribution [19].

The CFA was performed to examine the goodness of fit indices of the Malay OAKHQOL latent construct. Construct validity examines the degree to which a scale measures what it intends to measure [20]. Construct validity is achieved if the goodness of fit indices signify a model fit [20].

The measurement of the model fit was checked with several goodness of fit indicators: comparative fit index (CFI), Tucker-Lewis index (TLI), incremental fit index (IFI), chi-squared/degree of freedom, and root mean square error of approximation (RMSEA) [12, 13, 21]. For approximate fit index, a value of more than 0.9 was taken for CFI, IFI, and TLI [21, 22]. Chi-squared/degree of freedom of less than 3 and RMSEA value of less than 0.08 were taken as indicators of an acceptable level [12, 13, 19].

In addition to the overall evaluation of goodness of fit, the standardized factor loading (standardized regression weight) modification indices (MI) and squared multiple correlation () were used as indicators to select which items should be removed in the model [12, 13]. MI suggested correlations between variables. A high MI value indicates redundancy in a pair of variables [12, 13]. Discriminant validity is also assessed by obtaining correlation values between the constructs. A correlation of more than 0.85 between constructs is considered to indicate poor discriminant validity [12, 13].

Reliability analysis was measured using Cronbach’s alpha coefficient, composite reliability (CR), and average variance extracted (AVE). Reliability refers to the accuracy and precision of the measurement procedure. Cronbach’s alpha coefficient was measured using SPSS. Both CR and AVE were derived from CFA analysis and manually calculated based on published formula [19, 23]. A Cronbach’s alpha coefficient value of more than 0.7 and a CR equal to or greater than 0.6 represent a measure of satisfactory internal consistency [19, 24, 25]. AVE is the average percentage of variation explained by the variables in the construct or domain. The acceptable value for it was taken as more than 0.5 [19]. In this study, the test-retest reliability was not done due to time constraint and limited budget.

The Pearson correlation test was performed to assess the criterion validity of the OAKHQOL. The test was done between the pain construct of the OAKHQOL and the pain construct of the WOMAC, as well as between the physical construct of the OAKHQOL and the functional construct of the WOMAC. The correlation coefficient of more than 0.5 but less than 0.8 was considered to be a good correlation [26].

Known group validity is a method to support construct validity of a questionnaire. The method will evaluate the questionnaire ability to discriminate between the two groups known to differ on the variable of interest [27]. In this study, known group validity was assessed through gender, BMI, age groups of the patients, and Kellgren–Lawrence grading of the knee radiograph. We hypothesized that females, those aged more than 60 years [28], those having a BMI greater than 25 kg/m², and those with more severe radiographic grading would have significant differences [10]. An independent -test was used to analyze for gender, BMI, and age groups of the patients. One-way ANOVA test was used to analyze radiographic grading based on Kellgren–Lawrence classification. In the analysis for known group validity, the score for each domain was normalized to 0–100.

3. Results

3.1. Translation and Cultural Adaptation

We found that all the items in the Malay version questionnaire are relevant and appropriate to the Malaysian population. All the items were found to be acceptable, clear, and easy to understand in the face validity.

3.2. Psychometric Properties

A total of 191 patients participated in the study. The sociodemographic and knee OA disease characteristics of the participants are shown in Table 1. The mean age was 57.8 (6.8) years and the majority were female. The Kellgren–Lawrence classification ranged from grade 0 to 4.

Table 1: Sociodemographic and clinical characteristics of knee OA patients.

Variables
Mean
(SD)
(%)

Age (year)
57.8
6.8

Gender:

Male

63 (33)

Female

128 (67)

Education:

Primary

30 (15.7)

Secondary

132 (69.1)

Tertiary

29 (15.2)

Race:

Malay

186 (97.4)

Chinese

5 (2.6)

BMI (kg/m²)
28.5
5.1

Duration of knee OA (year)
3.7
3.7

Knee joint affected

Left

43 (22.5)

Right

34 (17.8)

Both

114 (59.7)

Kellgren–Lawrence classification:

0

59 (30.9)

1

68 (35.6)

2

33 (17.3)

3

27 (14.1)

4

4 (2.1)

3.3. Descriptive Statistics of the Items

The items in the five constructs of OAKHQOL had missing data ranging from 0 to 3 values (0%–1.5%). However, the individual items concerning professional life, relationships, and sexual activities had 10 to 13 missing values. The missing values were replaced with the mean scores for the domain during the CFA. Normality assessment was done for the 40 items in the five constructs using histogram, box-plot, and measurement of skewness, which showed normal distribution. The absolute and percentage frequencies of the score for all the items were calculated and illustrated in Table 2.

Table 2: Absolute and percentage frequencies of score for all items.

Score item
0
1
2
3
4
5
6
7
8
9
10
Total

Py1
Freq
11
24
20
24
26
38
12
20
7
3
6
191

%
5.8
12.6
10.5
12.6
13.6
19.9
6.3
10.5
3.7
1.6
3.1
100

Py2
Freq
9
14
25
23
15
37
17
21
13
10
7
191

%
4.7
7.3
13.1
12.0
7.9
19.4
8.9
11.0
6.8
5.2
3.7
100

Py3
Freq
11
15
16
12
23
32
25
19
16
15
7
191

%
5.8
7.9
8.4
6.3
12.0
16.8
13.1
9.9
8.4
7.9
3.7
100

Py4
Freq
8
10
11
21
22
45
20
23
15
12
4
191

%
4.2
5.2
5.8
11.0
11.5
23.6
10.5
12.0
7.9
6.3
2.1
100

Py5
Freq
7
8
12
15
20
23
32
33
20
15
6
191

%
3.7
4.2
6.3
7.9
10.5
12.0
16.8
17.3
10.5
7.9
3.1
100

Py6
Freq
49
32
25
23
14
22
9
7
4
4
2
191

%
25.7
16.8
13.1
12.0
7.3
11.5
4.7
3.7
2.1
2.1
1.0
100

Py7
Freq
35
22
21
16
20
26
22
11
10
7
1
191

%
18.3
11.5
11.0
8.4
10.5
13.6
11.5
5.8
5.2
3.7
0.5
100

Py8
Freq
35
24
18
16
14
28
16
11
15
9
5
191

%
18.3
12.6
9.4
8.4
7.3
14.7
8.4
5.8
7.9
4.7
2.6
100

Py9
Freq
2
13
17
11
20
32
28
21
17
23
7
191

%
1.0
6.8
8.9
5.8
10.5
16.8
14.7
11.0
8.9
12.0
3.7
100

Py10
Freq
18
14
19
16
17
36
27
16
12
10
6
191

%
9.4
7.3
9.9
8.4
8.9
18.8
14.1
8.4
6.3
5.2
3.1
100

Py11
Freq
33
15
14
14
31
25
14
12
12
7
4
191

%
17.3
7.9
7.3
7.3
16.2
13.1
7.3
6.3
6.3
3.7
7.3
100

Py13
Freq
45
24
23
18
17
27
17
13
2
2
3
191

%
23.6
12.6
12.0
9.4
8.9
14.1
8.9
6.8
1.1
1.1
1.6
100

Py14
Freq
31
17
22
20
21
32
16
15
11
3
3
191

%
16.2
8.9
11.5
10.5
11.0
16.8
8.4
7.9
5.8
1.6
1.6
100

M15
Freq
25
19
21
19
22
29
23
13
8
9
3
191

%
13.1
9.9
11.0
9.9
11.5
15.2
12.0
6.8
4.2
4.7
1.6
100

M16
Freq
20
21
19
18
14
27
25
20
13
7
7
191

%
10.5
11.0
9.9
9.4
7.3
14.1
13.1
10.5
6.8
3.7
3.7
100

M17
Freq
18
26
21
16
17
26
20
18
16
8
5
191

%
9.4
13.6
11.0
8.4
8.9
13.6
10.5
9.4
8.4
4.2
2.6
100

M18
Freq
40
20
18
20
17
22
16
12
15
7
4
191

%
20.9
10.5
9.4
10.5
8.9
11.5
8.4
6.3
7.9
3.7
2.1
100

M19
Freq
36
28
18
15
18
29
17
12
8
7
3
191

%
18.8
14.7
9.4
7.9
9.4
15.2
8.9
6.3
4.2
3.7
1.6
100

M20
Freq
33
27
22
17
16
34
15
9
6
9
3
191

%
17.3
14.1
11.5
8.9
8.4
17.8
7.9
4.7
3.1
4.7
1.6
100

M21
Freq
51
27
13
22
7
29
11
13
9
7
2
191

%
26.7
14.1
6.8
11.5
3.7
15.2
5.8
6.8
4.7
3.7
1.0
100

Py24
Freq
6
11
19
19
18
27
27
19
22
15
8
191

%
3.1
5.8
9.9
9.9
9.4
14.1
14.1
9.9
11.5
7.9
4.2
100

Py25
Freq
100
21
16
10
6
14
4
5
3
4
8
191

%
52.4
11.0
8.4
5.2
3.1
7.3
2.1
2.6
1.6
2.1
4.2
100

Pn26
Freq
9
16
23
24
20
30
13
21
15
12
8
191

%
4.7
8.4
12.0
12.6
10.5
15.7
6.8
11.0
7.9
6.3
4.2
100

Pn27
Freq
20
14
25
25
16
31
18
16
14
6
6
191

%
10.5
7.3
13.1
13.1
8.4
16.2
9.4
8.4
7.3
3.1
3.1
100

Py28
Freq
46
31
15
18
12
27
13
12
7
7
3
191

%
24.1
16.2
7.9
9.4
6.3
14.1
6.8
6.3
3.7
3.7
1.6
100

M29
Freq
39
24
18
17
18
30
22
4
9
8
2
191

%
20.4
12.6
9.4
8.9
9.4
15.7
11.5
2.1
4.7
4.2
1.0
100

Sf30
Freq
20
8
24
17
14
34
15
8
14
16
21
191

%
10.5
4.2
12.6
8.9
7.3
17.8
7.9
4.2
7.3
8.4
11.0
100

Sf31
Freq
17
12
18
20
14
36
18
6
7
19
24
191

%
8.9
6.3
9.4
10.5
7.3
18.8
9.4
3.1
3.7
9.9
12.6
100

Sf32
Freq
12
12
12
19
24
28
16
9
15
18
26
191

%
6.3
6.3
6.3
9.9
12.6
14.7
8.4
4.7
7.9
9.4
13.6
100

Pn33
Freq
44
24
21
13
12
32
16
9
14
4
2
191

%
23.0
12.6
11.0
6.8
6.3
16.8
8.4
4.7
7.3
2.1
1.0
100

Pn34
Freq
51
24
21
11
17
27
13
10
13
3
1
191

%
26.7
12.6
11.0
5.8
8.9
14.1
6.8
5.2
6.8
1.6
0.5
100

M35
Freq
19
33
30
17
13
37
11
12
8
6
5
191

%
9.9
17.3
15.7
8.9
6.8
19.4
5.8
6.3
4.2
3.1
2.6
100

M36
Freq
40
29
23
17
20
30
11
7
9
4
1
191

%
20.9
15.2
12.0
8.9
10.5
15.7
5.8
3.7
4.7
2.1
0.5
100

M37
Freq
68
29
19
15
15
26
7
4
3
5
0
191

%
35.6
15.2
9.9
7.9
7.9
13.6
3.7
2.1
1.6
2.6
0
100

M38
Freq
37
28
20
18
17
34
12
9
9
6
1
191

%
19.4
14.7
10.5
9.4
8.9
17.8
6.3
4.7
4.7
3.1
5
100

Sp39
Freq
9
11
12
16
14
23
17
23
16
16
34
191

%
4.7
5.8
6.3
8.4
7.3
12.0
8.9
12.0
8.4
8.4
17.8
100

Sp40
Freq
9
9
15
11
13
39
14
12
26
21
22
191

%
4.7
4.7
7.9
5.8
6.8
20.4
7.3
6.3
13.6
11.0
11.5
100

M41
Freq
45
24
22
17
11
37
13
6
6
7
3
191

%
23.6
12.6
11.5
8.9
5.8
19.4
6.8
3.1
3.1
3.7
1.6
100

sp42
Freq
10
6
16
12
9
23
13
16
14
20
52
191

%
5.2
3.1
8.4
6.3
4.7
12.0
6.8
8.4
7.3
10.5
27.2
100

sp43
Freq
11
10
13
15
12
28
16
15
19
18
34
191

%
5.8
5.2
6.8
7.9
6.3
14.7
8.4
7.9
9.9
9.4
17.8
100

Py: physical activity; m: mental health; pn: pain; sf: social functioning; sp: social support.

3.4. Confirmatory Analysis

Confirmatory factor analysis was performed with one-step strategy. Confirmatory analysis showed that the original five-factor model of the OAKHQOL (40 items) was not fit (Table 3). Five items (py25, m36, m37, m38, and m16) were removed one by one due to low factor loadings, as shown in Model A. Eight items were set as free parameter estimates, one pair at a time (py1-py2, py7-py8, py4-py5, and pn34-pn33), based on high MI (greater than 15) as shown in Model C. Further item deletion was done based on MI and factor loadings (py3, py9, m29, py24, sp39, py14, and py13) until the final model, which consists of a five factors with 28 items, signified a model fit (Table 3). The final model consists of five constructs: physical activity (10 items), mental health (eight items), social functioning (three items), social support (three items), and pain (four items). Six items in the physical activity, five items in the mental health, and one item in the social support were removed. The goodness of fit indices indicated that the model had a good construct (CFI = 0.915, TLI = 0.905, IFI = 0.916, chi-squared/degree of freedom = 1.953, and RMSEA = 0.071) (Table 3).

Table 3: Fitness level of models.

5-factor model
RMSEA
CFI
IFI
TLI
Chi
Square/df
Actions taken

Original:
(40 item)
0.100
0.770
0.772
0.754
2.908

Model A:
35 items
0.094
0.826
0.827
0.811
2.680
Delete

py25, m36, m37, m38

m16

Model B:
35 items
0.094
0.843
0.844
0.829
2.680
Correlate between the errors

py7-py8

py4-py5

py1-py2

pn33-pn34

Model C
30 items
0.090
0.901
0.902
0.890
2.061
Delete: py3, py9,

m29, py24, sp 39

Final model:
28 items
0.071
0.915
0.916
0.905
1.953
Delete py14 and py13

CFI: comparative fit index; TLI: Tucker-Lewis index; IFI: incremental fit index; RMSEA: root mean squared error of approximation.

The initial model before fit was shown in Figure 1. The correlation between factors was illustrated in Figure 2. The standardized factor loadings were from 0.5 to 0.9, indicating that all items contributed highly to the construct measures. The MI values were less than 10, and the correlation between each pair of latent constructs was less than 0.85, which is acceptable (Figure 2) [19].

Figure 1: The initial AMOS graphic shows the goodness of fit indexes, respective path coefficient, factor loading, and 2. PHY: physical activity, SOCF: social functioning, SOCP: social support, MEN: mental health, PAN: pain.

Figure 2: The AMOS graphic shows the goodness of fit indexes, respective path coefficient, factor loading, and 2. The final model shows 5 constructs and 28 items. PHY: physical activity, SOCF: social functioning, SOCP: social support, MEN: mental health, PAN: pain.

3.5. Reliability

The reliability analysis showed that the Cronbach’s alpha coefficient value for each construct was greater than 0.7 (Table 4). The CR and AVE of each construct also showed that the final construct had a good measure of reliability. The result was achieved by using one-step estimation strategy.

Table 4: Reliability and confirmatory factor analysis of the Malay version OAKHQOL.

Construct
Item
Factor loading
Cronbach alpha
CR

AVE

Physical activity
py1
0.774
0.933
0.915
0.743

py2
0.736

py4
0.653

py5
0.646

py6
0.672

py7
0.771

py8
0.716

py10
0.804

py11
0.679

py28
0.742

Mental
m15
0.773
0.919
0.921
0.796

m17
0.754

m18
0.726

m19
0.899

m20
0.910

m21
0.798

m35
0.656

m41
0.608

Social functioning
sf30
0.756
0.865
0.867
0.867

sf31
0.851

sf32
0.871

Social support
sp40
0.786
0.888
0.890
0.686

sp42
0.871

sp43
0.901

Pain
pn34
0.538
0.809
0.819
0.540

pn33
0.657

pn27
0.834

pn26
0.847

CR: construct reliability; AVE: average variance extracted.

Table 5 shows the Pearson’s correlation coefficients between the physical activity construct of the OAKHQOL and the functional construct of the WOMAC ( = 0.72) and between the pain construct of the OAKHQOL and pain construct of the WOMAC ( = 0.55). These results indicated that the OAKHQOL had acceptable criterion validity.

Table 5: Pearson correlation coefficient.

value

Physical activity domain OAKHQOL and functional domain WOMAC
0.72
<0.001

Pain domain WOMAC and pain domain OAKHQOL
0.55
<0.001

Correlation is significant at the 0.05 level (2-tailed).

3.6. Known Group Validity

The results for the known group validity of the OAKHQOL are shown in Table 6. We found significant differences among the BMI groups (BMI ≤ 25 kg/m² and >25 kg/m²) in the physical activity ( = 0.009), mental ( = 0.040), and pain domains ( = 0.009). We also found significant differences among the groups based on OA severity according to radiographic grading in the physical activity ( = 0.002) and pain domains ( = 0.043). Thus, groups who had greater disease severity based on radiography had worse scores. The scores of the pain domain for the age groups (age ≤ 60 years compared to those age > 60 years) were also significant. There were no differences observed for the social support and social function domains.

Table 6: Known group validity of the Malay version OAKHQOL.

Variables

Physical
Mental
Pain
Social functioning
Social support

Mean
SD
value
Mean
SD
value
Mean
SD
value
Mean
SD
value
Mean
SD
value

Gender:

0.208

0.370

0.890

0.761

0.328

Male
63
37.5
17.7

33.8
22.4

37.7
20.9

49.9
29.2

57.4
27.4

Female
128
41.8
21.5

36.7
22.2

38.2
23.5

51.2

27.4

61.5
28.3

Age:

0.321

0.208

0.025

0.767

0.929

≤60 years
161
39.7
19.9

34.8
22.2

36.7
21.9

51.1
28.2

60.3
27.9

>60 years
30
43.6
22.2

40.1
22.5

45.1
25.5

49.2
26.9

59.8
29.2

BMI

0.009

0.040

0.009

0.434

0.940

<25
50
32.5

30.2

30.9
20.2

53.5
29.3

59.9
28.6

≥25
141
42.3

37.7

40.5
22.9

49.9
27.4

60.2
27.9

KL grading

0.002

0.125

0.043

0.527

0.424

0
59
37.8
18.1

33.6
22.4

38.4
22.9

47.6
30.1

58.1
27.9

1
68
36.4
19.2

32.0
20.7

32.6
21.1

51.2
29.3

59.9
29.5

2
33
42.7
21.1

41.2
21.1

39.3
20.8

57.5
21.9

64.9
24.9

3
27
50.0
22.6

41.7
26.0

47.5
24.7

47.7
26.4

56.7
28.9

4
4
69.3
13.5

46.3
13.3

50.0
29.8

56.7
24.6

80.9
13.4

BMI: body mass index (kg/m²), KL: Kellgren–Lawrence grading of knee X-ray.

Table 7: Prevalidation of Malay version of OAKHQOL questionnaire (40 items).

Domain

1
Saya mengalami kesusahan untuk berjalan
py1

2
Saya mengalami kesusahan untuk tunduk atau meluruskan badan/bangun semula
py2

3
Saya mengalami kesusahan untuk membawa barang yang berat
py3

4
Saya mengalami kesusahan untuk menuruni tangga
py4

5
Saya mengalami kesusahan untuk menaiki tangga
py5

6
Saya mengalami kesusahan untuk mandi
py6

7
Saya mengalami kesusahan untuk berpakaian lengkap (seperti memakai stoking, kasut, seluar dan sebagainya)
py7

8
Saya mengalami kesusahan untuk memotong kuku kaki
py8

9
Saya mengalami kesusahan untuk bergerak selepas lama berada dalam kedudukan yang sama
py9

10
Saya mengalami kesusahan untuk masuk dan keluar daripada kereta
py10

11
Saya mengalami kesusahan untuk menggunakan kenderaan awam (bas, teksi dsb)
py11

12
Saya perlukan masa untuk bersendiri/saya perlu bersendiri
py13

13
Saya memerlukan masa yang lebih lama untuk melakukan sesuatu perkara
py14

14
Saya kurang bersemangat disebabkan sakit
m15

15
Saya risau jika saya perlu bergantung kepada orang lain
m16

16
Saya risau menjadi tidak berkemampuan
m17

17
Saya merasa malu apabila orang melihat saya
m18

18
Saya berasa gelisah
m19

19
Saya berasa tertekan
m20

20
Saya merasakan kehidupan keluarga saya terjejas
m21

21
Saya mengalami kesusahan untuk berada dikedudukan yang sama untuk jangkamasa yang lama (duduk, berdiri, tidak bergerak dsb)
py24

22
Saya memerlukan tongkat atau alat bantu untuk berjalan
py25

23
Saya mengalami kesakitan (kekerapan)
pn26

24
Saya mengalami kesakitan (keterukan)
pn27

25
Saya memerlukan pertolongan untuk membuat sesuatu seperti kerja rumah dan membeli belah
py28

26
Saya rasa lebih tua daripada umur saya
m29

27
Saya mampu/boleh merancang projek/program untuk jangkamasa yang panjang
sf30

28
Saya keluar rumah sekerap mana yang saya suka
sf31

29
Saya melayan tetamu di rumah sebanyak mana yang saya suka
sf32

30
Saya mengalami kesukaran untuk tidur atau tidur semula kerana sakit
pn33

31
Saya terjaga disebabkan sakit
pn34

32
Saya tertanya-tanya apa yang bakal berlaku/kan terjadi kepada saya
m35

33
Saya pemarah/mudah marah atau agresif
m36

34
Saya rasa saya menyakiti hati mereka yang rapat dengan saya
m37

35
Saya merasa risau tentang kesan sampingan rawatan saya
m38

36
Saya boleh berkongsi dengan orang lain tentang kesukaran yang saya alami disebabkan penyakit sendi (arthritis) sebanyak mana yang saya suka
sp39

37
Saya merasakan orang lain faham tentang kesusahan yang saya alami disebabkan penyakit sendi (arthritis) saya
sp40

38
Saya merasa malu untuk meminta bantuan/pertolongan jika perlu
m41

39
Saya rasa saya diberi sokongan oleh orang yang rapat dengan saya (pasangan dan keluarga)
sp42

40
Saya rasa saya diberi sokongan oleh orang yang berada di sekeliling saya (kawan dan jiran)
sp43

Py: physical activity; m: mental; pn: pain; sf: social functioning; sp: social support.

Table 8: Prevalidation of English version of OAKHQOL questionnaire (40 items).

Domain

1
I have difficulty walking
py1

2
I have difficulty bending down or straightening up
py2

3
I have difficulty carrying heavy things
py3

4
I have difficulty going down stairs
py4

5
I have difficulty climbing stairs
py5

6
I have difficulty taking a bath
py6

7
I have difficulty getting dressed
py7

8
I have difficulty cutting my toe-nails
py8

9
I have difficulty getting going again after staying in the same position for a long time
py9

10
I have difficulty getting in and out of a car
py10

11
I have difficulty using public transport
py11

12
I have to pace myself
py13

13
I take more time to do things
py14

14
My spirits are low because of the pain
m15

15
I worry about being dependent on others
m16

16
I worry about being disabled
m17

17
I feel embarrassed when people look at me
m18

18
I am anxious
m19

19
I am depressed
m20

20
I feel my family life is being affected
m21

21
I have difficulty staying in the same position for a long time
py24

22
I need a walking stick/cane or crutches to walk
py25

23
I have pain (describe frequency)
pn26

24
I have pain (describe intensity)
pn27

25
I need help for things like housework and shopping
py28

26
I feel older than my age
m29

27
I am able to plan projects for the long term
sf30

28
I get out of the house as much as I like
sf31

29
I entertain at home as much as I like
sf32

30
I have difficulty getting to sleep or getting back to sleep because of pain
pn33

31
I wake up because of pain
pn34

32
I wonder what will become of me
m35

33
I am irritable or aggressive
m36

34
I feel I annoy those close to me
m37

35
I am worried about the side effects of my treatment
m38

36
I can talk to others about the difficulties I have due to my arthritis as much as I like
sp39

37
I feel others understand the difficulties I have because of my arthritis
sp40

38
I am embarrassed to ask for help if I need it
m41

39
I feel supported by people close to me
sp42

40
I feel supported by those around me
sp43

Py: physical activity; m: mental; pn: pain; sf: social functioning; sp: social support.

4. Discussion

Recently, validated health-related quality of life that accurately reflects a patient’s experience with respect to specific disease has been an important outcome recommended for interventional study. Health-related quality of life is a broad concept representing individual responses to physical, mental, and social effects on daily living. Therefore, the need to assess conceptual relevance and psychometric properties in various cultures or countries is increasing [15].

The present study indicated that the shortened Malay version of the OAKHQOL had good validity and reliability and is culturally acceptable. EFA of the original OAKHQOL using principle component analysis with orthogonal varimax rotation revealed four factors: physical activities, mental health, social support, and social functioning with the pain factor as an individual dimension [10, 15]. The OAKHQOL has also been validated in Spanish and Persian [2, 29]. However, to our knowledge, this is the first study that used confirmatory analysis in the validation analysis. CFA is used to verify the factor structure of a measurement instrument. CFA has become more commonly used for construct validation and to provide evidence for convergent and discriminant validity of the theoretical construct [30]. Furthermore, CFA is a theory-testing model and it starts with a hypothesis prior to the analysis which is based on strong theoretical and/or empirical foundation [31]. On the other hand, EFA is used to explore the possible underlying factor structure of a measurement instrument [32].

The panel in this study decided to keep the original five-factor model in the initial analysis, although the EFA of the original study did not support this. EFA of the original study was done in other language; thus the result was different. The decision to keep the pain construct in the final model was made because we found the pain factor to be an important domain that is also available in and consistent with other health-related QOL for OA measures and the items were also culturally acceptable [16, 17].

We made the decision to remove six items from the physical activity construct (py3, py9, py13, py14, py24, and py25), five items in the mental health construct (m16, m29, m36, m37, and m38), and one item in the social support construct (sp39) because other items in the construct reflected similar functions. Most of the items were removed because of significant overlapping (high modification indices) and lack of discrimination within the items. Removal of these items was shown to improve the fit indices of the model, indicating that perhaps they poorly represented the construct being measured. However, the panel of this study had also revisited and reviewed the items before they were removed because they might represent important and meaningful construct as mentioned in a previous validation study.

The reliability analysis showed that internal consistency of the Malay version OAKHQOL was acceptable. Other than that, the CR and AVE for each construct were also acceptable, indicating that they had good levels of internal consistency. As for the criterion validity, the analysis showed that the physical and pain constructs of the Malay version of OAKHQOL had good correlations with the functional and pain constructs of the WOMAC. In Malay version of OAKHQOL, physical activity construct has 10 items whereas WOMAC has 17 items in functional construct [16]. In physical activity and functional construct of both questionnaires, daily activities such as difficulty in walking, bending, going up and down the stairs, and getting in and out of a car or a bus were assessed. Physical activity on self-care such as taking bath, getting dressed, and cutting toe-nails was assessed in OAKHQOL, whereas WOMAC assessed other aspects of daily activities such as difficulty in sitting, standing, lying on bed, getting up from sitting or from bed, shopping, and also doing house chores [16]. Perhaps future research can examine the criterion validity for the mental construct, social functioning, and social support of the Malay version of OAKHQOL. The SF36 is one questionnaire that has been used to assess health-related QOL for people with knee OA, although it is not disease-specific. This questionnaire has been validated in the Malay language. We suggest correlating the OAKHQOL scores with the SF36 in a future study.

For the known group validity, we found that the Malay version of OAKHQOL discriminates well for the BMI groups and the severity of disease based on plain radiograph for the physical activity, pain, and mental domains. However, for the social domains, it was not discriminative based on disease severity. This finding was similar to the findings of De Tejada et al., who conducted the validation study in Spanish [2]. Both Malay and English versions after validation are shown in Tables 9 and 10.

Table 9: Postvalidation of English version of OAKHQOL questionnaire (28 items).

Domain

1
I have difficulty walking
py1

2
I have difficulty bending down or straightening up
py2

3
I have difficulty going down stairs
py4

4
I have difficulty climbing stairs
py5

5
I have difficulty taking a bath
py6

6
I have difficulty getting dressed
py7

7
I have difficulty cutting my toe-nails
py8

8
I have difficulty getting in and out of a car
py10

9
I have difficulty using public transport
py11

10
My spirits are low because of the pain
m15

11
I worry about being disabled
m17

12
I feel embarrassed when people look at me
m18

13
I am anxious
m19

14
I am depressed
m20

15
I feel my family life is being affected
m21

16
I have pain (describe frequency)
pn26

17
I have pain (describe intensity)
pn27

18
I need help for things like housework and shopping
py28

19
I am able to plan projects for the long term
sf30

20
I get out of the house as much as I like
sf31

21
I entertain at home as much as I like
sf32

22
I have difficulty getting to sleep or getting back to sleep because of pain
pn33

23
I wake up because of pain
pn34

24
I wonder what will become of me
m35

25
I feel others understand the difficulties I have because of my arthritis
sp40

26
I am embarrassed to ask for help if I need it
m41

27
I feel supported by people close to me
sp42

28
I feel supported by those around me
sp43

Py: physical activity; m: mental; pn: pain; sf: social functioning; sp: social support.

Table 10: Postvalidation of Malay version of OAKHQOL questionnaire (28 items).

Domain

1
Saya mengalami kesusahan untuk berjalan
py1

2
Saya mengalami kesusahan untuk tunduk atau meluruskan badan/bangun semula
py2

3
Saya mengalami kesusahan untuk menuruni tangga
py4

4
Saya mengalami kesusahan untuk menaiki tangga
py5

5
Saya mengalami kesusahan untuk mandi
py6

6
Saya mengalami kesusahan untuk berpakaian lengkap (seperti memakai stoking, kasut, seluar dan sebagainya)
py7

7
Saya mengalami kesusahan untuk memotong kuku kaki
py8

8
Saya mengalami kesusahan untuk masuk dan keluar daripada kereta
py10

9
Saya mengalami kesusahan untuk menggunakan kenderaan awam (bas, teksi dsb)
py11

10
Saya kurang bersemangat disebabkan sakit
m15

11
Saya risau menjadi tidak berkemampuan
m17

12
Saya merasa malu apabila orang melihat saya
m18

13
Saya berasa gelisah
m19

14
Saya berasa tertekan
m20

15
Saya merasakan kehidupan keluarga saya terjejas
m21

16
Saya mengalami kesakitan (kekerapan)
pn26

17
Saya mengalami kesakitan (keterukan)
pn27

18
Saya memerlukan pertolongan untuk membuat sesuatu seperti kerja rumah dan membeli belah
py28

19
Saya mampu/boleh merancang projek/program untuk jangkamasa yang panjang
sf30

20
Saya keluar rumah sekerap mana yang saya suka
sf31

21
Saya melayan tetamu di rumah sebanyak mana yang saya suka
sf32

22
Saya mengalami kesukaran untuk tidur atau tidur semula kerana sakit
pn33

23
Saya terjaga disebabkan sakit
pn34

24
Saya tertanya-tanya apa yang bakal berlaku/kan terjadi kepada saya
m35

25
Saya merasakan orang lain faham tentang kesusahan yang saya alami disebabkan penyakit sendi (arthritis) saya
sp40

26
Saya merasa malu untuk meminta bantuan/pertolongan jika perlu
m41

27
Saya rasa saya diberi sokongan oleh orang yang rapat dengan saya (pasangan dan keluarga)
sp42

28
Saya rasa saya diberi sokongan oleh orang yang berada di sekeliling saya (kawan dan jiran)
sp43

Py: physical activity; m: mental; pn: pain; sf: social functioning; sp: social support.

This study is not without limitation. First, this study involved only people with knee OA; therefore, the findings may not be generalized to patients with hip OA. In addition, the convenient sampling was applied. Thus, it may not represent the true knee OA population in the community. It is also good to measure the responsiveness of this questionnaire in a clinical trial where it can be used to evaluate changes in patient status following therapeutic intervention.

5. Conclusion

The Malay version of OAKHQOL consisting of five factors assessed through 28 items was valid, reliable, and acceptable to measure quality of life in Malaysian population with knee OA.

Ethical Approval

This study protocol was approved by the Research Ethics Committee (Human), School of Medical Sciences, Universiti Sains Malaysia (FWA Reg. no. 00007718; IRB Reg. no. 00004494) and procedures followed were in accordance with the Helsinki Declaration of 1975.

Consent

The participants involved in the study have signed consent form to participate in the study.

Disclosure

An earlier version of this work was presented as a poster at the Medical Journal of Malaysia in 4th Asia Pacific Conference on Public Health.

Conflicts of Interest

The authors declare that there are no conflicts of interest regarding the publication of this article.

Acknowledgments

The authors would like to acknowledge the Universiti Sains Malaysia for the Grant (1001/PPSP/812132) to conduct this study. They also gratefully acknowledge the cooperation of all participating subjects and staff involved in this project. The authors would like to acknowledge the questionnaire’s author Anne-Christine Rat for giving them permission to use the OAKHQOL as well as a copy of the original English version.

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