Open Access

Further validation of the Health Scale of Traditional Chinese Medicine (HSTCM)

  • Darong Wu1,
  • Shilong Lai1, 2Email author,
  • Luojing Zhou1,
  • Xinfeng Guo2,
  • Weixiong Liang2,
  • Zehuai Wen2,
  • Aihua Ou1,
  • Guangqing Zhang1 and
  • Keji Chen3
Chinese Medicine20094:8

DOI: 10.1186/1749-8546-4-8

Received: 07 November 2008

Accepted: 30 April 2009

Published: 30 April 2009

Abstract

Background

Few health measurement scales are based on Chinese medicine theory. The Health Scale of Traditional Chinese Medicine (HSTCM) was developed to fill this gap. The aim of this study is to validate the HSTCM.

Methods

A convenience sample of 630 participants was recruited in 11 settings. All participants were asked to complete the HSTCM and World Health Organization Quality of Life Measure-Abbreviated Version (WHOQOL-BREF).

Results

Properties of the HSTCM were tested. Intra-class correlation coefficient representing the inter-interviewer reliability was 0.99 (95%CI) for the overall instrument. Spearman-Brown correlation coefficient and Cronbach's coefficient alpha were 0.81 and 0.94 respectively, indicating satisfactory internal reliability and inter-interviewer reliability. Spearman's rho correlation coefficient between the HSTCM and WHOQOL-BREFF was -0.67. A receiver operating characteristic (ROC) curve analysis was performed to test the discriminate validation. Areas under the ROC curve analysis for the HSTCM and its domains ranged 0.71–0.87 and all the lower levels of 95%CI were greater than 0.50.

Conclusion

The HSTCM was validated as a generic health scale and may complement existing health measurement scales in Chinese medicine health care.

Background

Acceptance of health measurement scales based on one's perception has increased in recent years [13]. Several well-established measures on health status or health-related Quality of Life (QOL) have been widely used [48]; however, few were developed on the basis of Chinese medicine which has been important for the well-being of the Chinese people for many years [9] and is now increasingly recognized worldwide [1012].

Measuring health in accordance with Chinese medicine theory is useful [13, 14]. Chinese medicine practitioners pay close attention to patients' subjective feelings for diagnosis and treatment. Different perspectives of the patients may lead to different prescriptions from the practitioner even if the patients suffer from the same condition [15]. Over the years, Chinese medicine practitioners have accumulated valuable experiences on obtaining information from the patient's perspective that may benefit their treatment strategy and judgment of clinical efficacy. We believe that these experiences can be more easily understood by clinicians and researchers if they were involved in some applicable instruments. Moreover, Chinese medicine and Western medicine work differently towards the end result. In Chinese medicine, information such as adaptation to climates and seasons, aversion to cold, positive feelings concerning the ability of maintaining stable mood is carefully captured as evidence for patients' adaptability with both natural and social environments. Although modern Chinese medicine practitioners may take biomarkers as references, there is a general impression among them that indicators reflect individual's adaptability may possess a more important position when testing the efficacy of a Chinese medicine treatment.

However, these indicators are usually not involved in common patient reported outcomes (PRO) or health related quality of life measures. A few other instruments were developed on the basis of Chinese medicine theory or for integrative medical research but none of them were based on a community sample [16, 17]. In addition, the commonly recognized and accepted set of standardized procedures [18, 19], from concept to measurement scale, makes it possible to develop an instrument based on Chinese medicine theory.

The Health Scale of Traditional Chinese Medicine (HSTCM), which is a generic scale designed for evaluating general health according to subjective feelings [20], is based on health concept of Chinese medicine and the operationalization of this concept's measurement [20, 21]. The HSTCM consists of three domains, namely physical function under natural environment (PFNE), spirit (SP) and social environment (SE), and 2 additional items (see Additional file 1). PFNE domain has four facets: physical functioning (PF), voice (VOC), stool and urine (SU), and adaptability of natural environment (ANE). SP domain also has four facets: confidence and content (CC), self-confidence (SC), energy (EG) and basic ability of thinking (BAT). SE domain has three facets: ability of communicating with people (ACP), adaptability of noisy condition (ANC) and ability of dealing with bad stimulations (ADBS). In 2003, the development of initial Health Scale of Traditional Chinese Medicine (iHSTCM) [20] and the refinement from the iHSTCM (88 items) to HSTCM (47 items) [21] were accomplished. It was shown that the HSTCM was conceptually sound and reliable [22]. However, the test of psychometric properties using various independent samples may still be needed, particularly construct validation, according to the principles of instrument development [23, 24]. Meanwhile, the previous test was based on data collected through iHSTCM (containing 88 items [21, 22]); it is reasonable to test the psychometric properties again with the revised version of HSTCM (containing 47 items).

The purpose of developing the HSTCM is similar to other generic health related QOL measures, e.g. the World Health Organization Quality of Life Measure-Abbreviated Version (WHOQOL-BREF) [25] and MOS 36-Item Short Form (SF-36) [6]. We used the WHOQOL-BREF (Chinese version) [26] as a comparison instrument when examining the validation of the HSTCM because of the excellent validity and reliability of the WHOQOL-BREF. It is also because the Chinese version of the WHOQOL-BREF has become one of the standard measurements of QOL in China.

The aim of this study is to validate the measurement properties of the HSTCM in a convenience sample.

Methods

Participants

Inclusion criteria for the participants are (a) 18 years of age or above and (b) speaking Putonghua (Mandarin Chinese). All participants were asked to complete both the HSTCM and WHOQOL-BREF. An oral agreement was obtained from each participant prior to interview.

Study instruments

The HSTCM includes 47 items, each with a five-degree response format, scoring 1, 2, 3, 4 and 5 respectively. Total scores range 0–225 (two additional items not included), whereby a high score indicates poor health. The Chinese version of the WHOQOL-BREF (Ministry of Health, China, 1999) [26] was taken in this study as a standard criterion. The instrument contains 26 core items and three additional items. The three additional items are only used in the mainland Chinese version.

Demographics

A demographic questionnaire covering gender, age, and highest educational attainment was provided at the end of the interview. Each participant completed the questionnaire in the presence of an interviewer.

Quality control of data collection

We produced a booklet entitled the Guide to the HSTCM Survey to set forth a standard operating procedure (SOP), rules of investigation, structured response to frequently asked questions for interviewers and structured oral interview guidance. A total of 25 interviewers, who were senior medical students or nurses, were trained with the booklet for 4–6 hours.

Data management and analysis

We compiled a coding notebook to ensure good quality of data entry. If there are two answers to one question that are next to each other, the auditor must choose one of the answers. However, if the two answers are not next to each other, the auditor must read the notes from the interviewers. If there are no related notes, the auditor must consider the answer as missing.

All data were double entered with EPI DATA 2.1a (EpiData Association Odense, Denmark). The final dataset was converted into SPSS format. Data were analyzed primarily with SPSS version 11.0 (SPSS, USA) while confirmatory factor analysis was performed with SPSS Amos 4.0. Demographic data were assessed with descriptive statistics. Reliability assessment was conducted between interviewers. Twenty-four of the 25 interviewers were divided into 12 pairs, two in one pair. A pair of interviewers questioned a participant and it was ensured that they could not see each other's records. One of them was in charge of the investigation, while the other recorded the answers only. It was decided randomly who would be in charge. Inter-interviewer reliability was performed by intra-class correlation coefficient (ICC) analysis. Cronbach's α statistics were used to assess the internal consistency reliability of the HSTCM, in which values greater than 0.6 were considered evidence of internal consistency [27]. Unequal-length Spearman-Brown prophecy coefficient was used to obtain the split-half reliability coefficient [28].

Using input from both the HSTCM focus groups and Chinese medicine practitioners, we performed the face and content validation during the design phase of the HSTCM [21] to assess how well the HSTCM measured the concepts. The HSTCM was further verified after the design phase with input from healthy participants and inpatients of Chinese medicine hospitals to ensure the questions' relevance.

Convergent validation of the HSTCM was assessed with Spearman's rho correlation coefficients between the scores of the HSTCM and WHOQOL-BREF. An absolute value within the range of 0.4–0.8 suggests that the convergent validation is appropriate [23].

To study the ability of the domain and overall HSTCM scores in discriminating groups of participants of possibly different health status, we divided the participants into three groups according to their self-reported general health status, self-reported health status change and degree of medical needs. The mean, standard deviation (SD) and 95% confidence interval (95%CI) of domain and overall HSTCM scores of each group were calculated. A lack of overlapping between the ranges of 95%CI of any two groups suggests that the domain or the HSTCM can distinguish these groups.

Receiver operating characteristic (ROC) curves [29, 30] were plotted for the HSTCM and its three domains. The area under the curve (AUC) was used as an indicator of the ability of the instrument to differentiate participants with or without good self-reported general health status. An AUC of greater than 0.50 indicates a discriminative accuracy to be greater than chance. A perfect discriminative ability would have an AUC of 1.0.

Principal component exploratory factor analysis with Equamax rotation was carried out to assess the underlying structure of the instrument among a set of questionnaire items. Confirmatory factor analysis was further performed to examine whether the data fit the applied model. Goodness of fit of the model was considered to be acceptable if root mean square error of approximation (RMSEA) is less than 0.08. Goodness of fit is good if RMSEA is less than 0.05[31]. Comparative fit index (CFI) of greater than 0.95 also indicates a satisfactory goodness of fit [32]. Values are considered statistically significant if P < 0.05.

Results

Range of responses

From December 2006 to February 2007, 630 participants as a convenience sample were recruited under 11 settings in the Liwan community in Guangzhou, China. Six hundred and twenty-nine participants returned both the HSTCM and WHOQOL-BREF questionnaires, giving an overall response rate of 99.8%. Six of the 629 questionnaires were excluded for not meeting the criteria of logical checking. Among the remaining 623 questionnaires, 611 responded to 80% or more of the items of both questionnaires (Figure 1). Missing values of the items were replaced in accordance with the series mean method.
https://static-content.springer.com/image/art%3A10.1186%2F1749-8546-4-8/MediaObjects/13020_2008_Article_42_Fig1_HTML.jpg
Figure 1

Participant selection process.

Demographics

Among the 611 participants, 58% were female and the mean age was 49 years. And 35.8% had completed high school and 15.9% had completed university or above. All participants were recruited under 11 settings of the Liwan community (Table 1). Among all demographic questionnaires, 66.9% were self-administered while 8.7% and 19.6% were interviewer-assisted and interviewer-administered respectively.
Table 1

Demographics of the participants

 

No

Individual percentage (%)

Settings of the Liwan community

  

   Dahua

75

12.3

   Fulixi

35

5.7

   Fulidong

46

7.5

   Huicheng

88

14.4

   Wenchang flower garden

46

7.5

   Fengyuanbei

50

8.2

   Community Service centre

11

1.8

   Majichong

100

16.4

   Huagui

64

10.5

   Houfu

53

8.7

   Dade

41

6.8

   Missing value

2

0.3

Age

  

   18–44

245

40.1

   45–64

218

35.7

   65 and older

145

23.7

   Missing value

3

0.5

Gender

  

   Female

356

58.3

   Male

252

41.2

   Missing value

5

0.5

Education

  

   Elementary school

139

22.7

   Junior high school

145

23.7

   High school

219

35.8

   Junior college and above

97

15.9

   Missing value

11

1.8

Interview method

  

   Self-administered

409

66.9

   Interviewer-assisted

53

8.7

   Interviewer-administered

120

19.6

   Missing value

29

4.7

Reliability

Interviewer reliability

The overall correlation between interviewers in the HSTCM was 0.99 (95%CI: 0.996–0.999). The correlation coefficient of the PFNE domain was 0.99 (95%CI: 0.995–0.999), the SP domain 0.99 (95%CI: 0.996–0.999) and the SE domain 0.99 (95%CI: 0.996–0.999). All the intra-class correlation coefficients (for both the total scale and its three domains) were greater than 0.95 (the lower level of 95%CI > 0.90), suggesting that the inter-interviewer reliability was satisfactory.

Internal reliability

We calculated the Spearman-Brown split-half reliability coefficient to examine the split-half reliability. The coefficient was 0.81, indicating a good split-half reliability of the HSTCM.

Internal reliability of the HSTCM and its three domains were estimated with the Cronbach's α coefficient (Table 2).
Table 2

Cronbach's α coefficient of the HSTCM domains and facets

 

Cronbach's α coefficient

No of items

HSTCM

0.93

45

1. PFNE

0.89

18

   PF

0.89

9

   VOC

0.75

2

   SU

0.70

2

   ANE

0.75

5

2. SP

0.90

14

   CC

0.88

6

   SC

0.90

2

   EG

0.83

4

   BAT

0.68

2

3. SE

0.87

13

   ACP

0.76

2

   ANC

0.32

2

   ADBS

0.89

9

The Cronbach's α coefficients of the HSTCM domains and the total score of the HSTCM were larger than 0.80. Except the ANC facet, of which the Cronbach's α coefficient was 0.32, the values of other facets were greater than 0.65.

Validation

Convergent validation and discriminative validation

We carried out convergent validation by correlating the total score of the HSTCM with that of the WHOQOL-BREF. The Spearman' rho correlation coefficient (r) was -0.67 (P < 0.001). The three-domain scores showed fair to moderate correlation with the four-domain scores of the WHOQOL-BREF. All the correlations were statistically significant. The physical function domain showed moderate correlation with physical domain (r = -0.55, P < 0.001) and had fair correlation between the psychological domain (r = -0.41, P < 0.001), social domain (r = -0.37, P < 0.001) and environmental domain (r = -0.31, P < 0.001) of the WHOQOL-BREF. The spirit domain showed higher correlation with the physical domain (r = -0.71, P < 0.001), psychological domain (r = -0.70, P < 0.001) and social domain (r = -0.53, P < 0.001) of the WHOQOL-BREF and fair correlation with the environmental domain (r = -0.47, P < 0.001). The social and environmental domain showed only fair correlation with all the four domains with correlation coefficient ranging from -0.32 (P < 0.001) in the social and environmental domain to -0.49 (P < 0.001) in the physical domain of the WHOQOL-BREF. The overall HSTCM score displayed significant correlation with all four domains of the WHOQOL-BREF. The correlation was moderate with the physical (r = -0.68, P < 0.001) and psychological domain (r = -0.62, P < 0.001) and fair with the social (r = -0.47) and environmental domain (r = -0.43, P < 0.001) of the WHOQOL-BREF (Table 3).
Table 3

Correlation between the HSTCM and WHOQOL-BREF domains

HSTCM domains

WHOQOL-BREF domains

Physical

Psychological

Social

Environmental

PFNE

-0.55

-0.41

-0.37

-0.31

SP

-0.71

-0.70

-0.53

-0.47

SE

-0.49

-0.47

-0.32

-0.32

Overall HSTCM

-0.68

-0.62

-0.47

-0.43

All correlations are significant at the 0.001 level (2-tailed).

In the HSTCM, a higher score means poorer health; in the WHOQOL-BREF, a higher value means better health.

Discriminative validation

The mean, standard deviation (SD), 95%CI of each group of the HSTCM and its domains were calculated (Tables 4 and 5). No overlapping of the 95%CI was found between the participants with good self-reported health status and those with poor self-reported health status in all three domain scores and the overall HSTCM scores. The same results were found between participants with better self-reported health status change and those with worse health status, and between participants with 'not at all/a little degree of medical needs' and those with 'very much/great degree of medical needs'. The overall HSTCM scores and the three domain scores differentiated all three levels of the self-reported health status indicators as well as discriminated the participants with 'not at all/a little degree of medical needs' from those with 'moderate needs'. However, the three domain scores and the overall HSTCM scores did not distinguish the participants with 'moderate medical needs' from those with 'very much/great medical needs'. Moreover, the scores did not distinguish the participants with 'better health statuses' from those with 'no change'.
Table 4

Discriminative ability of the HSTCM in terms of levels of health status

  

Scores of the HSTCM

No.

Mean

SD

95%CI

1. Self-reported general health status

    

   Good/very good

268

90.18

18.56

87.86–92.69

   Neither poor nor good

263

114.46

19.16

112.46–117.40

   Poor/very poor

78

132.92

21.50

128.03–137.80

   Missing value

2

-

-

-

2. Self-reported health status change

    

   Better

102

93.92

24.21

88.92–99.82

   No change

283

102.17

22.72

99.73–105.44

   Worse

226

116.25

22.50

113.54–119.76

   Missing value

0

-

-

-

3. Degree of medical needs

    

   Not at all/a little

331

97.56

21.33

94.47–99.42

   A moderate amount

189

115.97

22.17

113.36–119.86

   A great amount

88

117.20

26.98

113.44–125.45

   Missing value

3

-

-

-

Self-reported general health status is item 21 of the HSTCM; self-reported health status change is item 22 of the HSTCM; degree of medical needs is item 4 of the WHOQOL-BREF.

Table 5

Discriminate ability of the domains in terms of levels of health status

 

No

Scores of PFNE

Scores of SP

Scores of SE

Mean

SD

95%CI

Mean

SD

95%CI

Mean

SD

95%CI

1. Self-reported general health status

Good/very good

268

34.8

8.80

33.5–35.8

27.9

6.85

27.3–29.0

27.5

7.59

26.5–28.5

Neither poor nor good

263

45.3

9.82

44.4–46.9

36.6

6.60

35.9–37.6

32.6

7.68

31.5–33.5

Poor/very poor

78

51.2

11.77

49.1–54.6

44.4

6.78

42.9–45.9

36.5

8.09

34.8–38.6

Missing value

2

-

-

-

-

-

-

-

-

-

2. Self-reported health status change

Better

102

38.0

11.15

35.4–40.3

27.0

8.46

25.6–29.4

28.9

8.35

27.2–30.9

No change

283

39.4

11.07

38.3–41.1

32.9

7.87

32.1–34.0

29.8

8.03

28.8–30.8

Worse

226

45.5

10.90

44.2–47.3

37.8

7.79

36.8–39.0

33.0

8.26

31.8–34.1

Missing value

0

-

-

-

-

-

-

-

-

-

3. Degree of medical needs

Not at all/a little

331

37.8

9.61

36.3–38.6

30.8

8.04

30.0–31.7

29.0

7.87

27.8–29.6

A moderate amount

189

46.0

11.25

44.8–48.0

37.2

7.60

36.3–38.6

32.7

7.94

31.6–33.9

A great amount

88

45.7

13.30

43.6–49.6

37.4

9.56

36.1–40.3

34.1

8.95

32.6–36.6

Missing value

3

-

-

-

-

-

-

-

-

-

Self-reported general health status is item 21 of the HSTCM; self-reported health status change is item 22 of the HSTCM; degree of medical needs is item 4 of the WHOQOL-BREF.

PFNE: physical function under natural environment domain

SP: spirit domain

SE: social and environment domain

ROC curves showed the discriminate validation of the instrument (Figure 2). The AUC for the HSTCM and its domains were high and all the lower levels of 95%CI were greater than 0.5 (Table 6), suggesting that the instrument discriminated the participants in terms of self-reported health status.
Table 6

Areas under the ROC curves for the HSTCM and its domains in discriminate performance between participants with and without good self-reported general health status

Variable

Area under ROC curve

SE

Significant level

95%CI

    

Lower

Upper

PFNE

0.81

0.02

< 0.01

0.78

0.85

SP

0.85

0.02

< 0.01

0.82

0.88

SE

0.71

0.02

< 0.01

0.67

0.76

HSTCM

0.85

0.02

< 0.01

0.82

0.88

Null hypothesis: true area = 0.5 (Smaller test result indicates more positive test.)

Nonparametric distribution (95%CI)

https://static-content.springer.com/image/art%3A10.1186%2F1749-8546-4-8/MediaObjects/13020_2008_Article_42_Fig2_HTML.jpg
Figure 2

ROC curves for the HSTCM and its domains in discriminating performance between participants with good self-reported general health status and those without. HSTCM: Health Scale of Traditional Chinese Medicine; SE: social and environment domain; SP: spirit domain; PFNE: physical function under natural environment domain.

Construct validation

Exploratory factor analysis
The previous version of the HSTCM [21] did not include appetite and sleep. As appetite and sleep are often used in diagnosis and outcome assessment, the HSTCM focus group decided to include them as additional items of the HSTCM, bringing the total number of items to 47. However, these two items were not included in the validation analysis. By exploratory factor analysis, 45 items were summed up to nine factors (Table 7).
Table 7

Exploratory factor analysis of the nine facets of the HSTCM

 

1

2

3

4

5

6

7

8

9

1. PF

         

   Palpitation (T14)

0.753

        

   Chest distress (T15)

0.752

        

   Disorder of the taste (T18)

0.709

        

   Tinnitus (T20)

0.677

        

   Thirst (T17)

0.666

        

   Dizziness (T_13)

0.652

        

   Pain (T_16)

0.652

        

   Disorder of perspiration (T12)

0.638

        

   Gastrointestinal disorder (T19)

0.618

        

2. SDSC, CC

         

   Satisfaction of appearance (T31)

 

0.781

       

   Satisfaction of body figure (T30)

 

0.774

       

   Concerning the future (T29)

 

0.749

       

   Meaning of life (T32)

 

0.736

       

   Contented sensation of work (T28)

 

0.703

       

   Vivid (T26)

 

0.689

       

   Joy (T25)

 

0.678

       

   Confidence (T27)

 

0.674

       

3. ADBS

         

   Great concern (T39)

  

0.732

      

   Upset (T41)

  

0.721

      

   Afraid (T38)

  

0.696

      

   Tension and tired (T42)

  

0.683

      

   Scare (T40)

  

0.669

      

   Worry (T36)

  

0.599

      

   Hesitate (T43)

  

0.595

      

   Insomnia (T37)

  

0.579

      

   Annoyance (T35)

  

0.531

      

4. EG

         

   Self-reported health change (T22)

   

0.749

     

   Energy (T23)

   

0.748

     

   Self-reported general health(T21)

   

0.680

     

   Physical strength (T24)

   

0.675

     

5. ANE

         

   Cold weather (T2)

    

0.697

    

   Weather change (T1)

    

0.639

    

   Hot weather (T3)

    

0.615

    

   Season change (T4)

    

0.612

    

   Circumstance of temperature difference (T5)

    

0.586

    

6. VOC, SU

         

   Urine (T10)

     

0.677

   

   Stool (T11)

     

0.596

   

   Voice (T7)

     

0.630

   

   Voice change (T6)

     

0.452

   

7. ACP

         

   Nervous (T44)

      

0.773

  

   Adjustment disorders (T45)

      

0.753

  

8. BAT

         

   Activities of daily life (T33)

       

0.686

 

   Focus attentions (T34)

       

0.562

 

9. ANC

         

   Anti-disturbance capability (T46)

        

0.726

   Noisy environment (T47)

        

0.466

Extraction method: principal component analysis. Equamax rotation with Kaiser Normalization, sorted by size, factor loading < 0.4 suppressed

Result of the Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy test was 0.93, suggesting that the data were suitable for factor analysis [33]. The nine facets explained about 60.8% of the total variance of the data. The constructs of facet were very similar to those of the previous version. Only SC and CC, belonging to two facets, emerged in the same factor; so did VOC and SU. SC and CC were the facets of the SP domain, while VOC and SU belonged to the PFNE domain. These results showed that the constructs of facets were coherent with structures of the HSTCM domains.

We performed further exploratory factor analysis using scores of the nine facets resulting in three factors, which explains the total variance of 64.1% (Table 8).
Table 8

Exploratory factor analysis of the three domains of the HSTCM

 

1

2

3

PF

0.764

  

ANE

0.776

  

VOC, SU

0.632

  

SC, CC

 

0.814

 

EG

 

0.618

 

BAT

 

0.771

 

ACP

  

0.771

ANC

  

0.755

ADBS

  

0.518

Extraction method: principal component analysis Equamax rotation with Kaiser Normalization, sorted by size, factor loading < 0.4 suppressed

Confirmatory factor analysis
We constructed a model to carry out the confirmatory factor analysis (Figure 3). CFI of the model was above 0.90, while the RMSEA was less than 0.08. The goodness of fit was acceptable.
https://static-content.springer.com/image/art%3A10.1186%2F1749-8546-4-8/MediaObjects/13020_2008_Article_42_Fig3_HTML.jpg
Figure 3

Model of the confirmatory factor analysis between the HSTCM domains and facets.

Discussion

The properties of the HSTCM were tested in a group of participants in the Liwan community in Guangzhou, China. Measurement properties, internal reliability and inter-interviewer reliability of the HSTCM and its domains were satisfactory. The HSTCM had mild convergence with the WHOQOL-BREF (with a moderate correlation). The overall HSTCM scores and most of the domain scores discriminated groups of participants with known differences in health status. Confirmatory factor analysis showed a good structure fitness of the domains and overall structure.

In the reliability test, Cronbach's α was low in subscale ANC (0.32). As the items in the ANC facet met the selection criteria and Cronbach's α was considered to be acceptable on the whole scale and three domains' level; we may need further evidence before removing ANC from the scale.

In this study, we used the ROC analysis to evaluate the discriminate ability of the HSTCM. The AUC indicates that the HSTCM discriminate better than chance between groups with and without good self-reported health status. Therefore, the results of ROC analysis support the clinical validity of the HSTCM. However, this discriminate ability should not be confused with that of diagnostic instruments. Health status measures are not intended to be used at an individual patient level [34].

Construct validation is an ongoing process. The more frequently an instrument is used, the greater our confidence is in its validation [35]. Comparing the previous study [21] with the present one, we found that the construct validities of two independent samples were similar. Similar constructs in two independent studies strengthen the construct validation for the HSTCM. We may find some similar constructs in other health related QOL instruments based on Chinese medicine theory [16].

Items from SC and CC had similar meanings in terms of the HSTCM developmental theory, as did VOC and SU, which may be explained by the exterior-interior relations [36] between the large intestine meridian and lung meridian. The exterior-interior relations of the two meridians not only strengthen the connection between this specific pair of meridians, but also promote the large intestine/lung pair to coordinate with each other physiologically and influence each other pathologically. Items of the VOC facet are key indicators of the status of lung, while the SU facet contains an important predictor of the large intestine.

No test-retest reliability was conducted in the present study; however, results from the previous study suggest good test-retest reliability [22].

The attribute of 'responsiveness' is also considered as a component of a scale validation [37]. Based on the discriminative validation and measures of ROC, we think that the responsiveness of the scale is acceptable [38]. However, we did not estimate the parameter to compare the before-after changes caused by a given intervention, which means the inference may be limited.

In this study, participants were selected from a community by convenience sampling which is widely used in psychometric property testing, especially those of health scales [3943]. However, a convenience sample is less representative than a random sample and may limit the generalizability of this study.

We did not use item response theory (IRT) in developing and evaluating the HSTCM because the advantage of the IRT methods over traditional methods was not clear to us [44]. However, we think that IRT methods can be used to refine the scale. Generalizability theory (GT) is another powerful tool in analyzing scale reliability with complicated sources of measurement biases. Further studies with IRT to analyze item characteristic of the instrument and with GT to evaluate the validation of the HSTCM are warranted.

Conclusion

The HSTCM meets the basic requirements for a generic health scale and complements the existing health measurement scales for Chinese medicine health care.

Abbreviations

HSTCM: 

Health Scale of Traditional Chinese Medicine

WHOQOL-BREF: 

World Health Organization Quality of Life Measure-Abbreviated Version

SF-36: 

MOS 36-Item Short Form

PRO: 

patient reported outcomes

SOP: 

standard operating procedure

iHSTCM: 

initial Health Scale of Traditional Chinese Medicine

ICC: 

intraclass correlation coefficient

PFNE: 

physical function under natural environment domain

SP: 

spirit domain

SE: 

social and environment domain

PF: 

physical functioning facet

VOC: 

voice facet

SU: 

stool and urine facet

ANE: 

adaptability of natural environment facet

CC: 

confidence and content facet

SC: 

self-confidence facet

EG: 

energy facet

BAT: 

basic ability of thinking facet

ACP: 

ability of communicating with people facet

ANC: 

adaptability of noisy condition facet

ADBS: 

ability of dealing with bad stimulations facet

ROC: 

receiver operating characteristic

AUC: 

area under curve

CFI: 

comparative fit index

RMSEA: 

root mean square error of approximation

IRT: 

item response theory

GT: 

generalizability theory.

Declarations

Acknowledgements

This work was supported by the State Administration of Traditional Chinese Medicine of the People's Republic of China (No.04-05JP50), the Finance Department of Guangdong Province (No. 2 [2006]143) and the Guangzhou University of Chinese Medicine (No. 84). We are grateful to Drs Zhigang Zhong, Nuo Su and others from the Health Service Centre of Fengyuan Road, Liwan community, Guangzhou, China for their kind assistance in the investigation. We also thank all the interviewers and participants who took part in this study.

Authors’ Affiliations

(1)
Second Affiliated Hospital of the Guangzhou University of Chinese Medicine
(2)
Guangzhou University of Chinese Medicine
(3)
Xiyuan Hospital, China Academy of Chinese Medical Sciences

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© Wu et al; licensee BioMed Central Ltd. 2009

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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