Content validity and cultural relevance.
All members of the expert panel agreed that 3 of the 12 subscales (mobility level, self-care tasks, and arthritis pain) were highly relevant components of health status of people with arthritis. Six other subscales (walking and bending, hand and finger function, arm function, household tasks, work, and mood) were rated as relevant. Three subscales (social activities, support from family and friends, and level of tension) were rated as poorly relevant by 1 panel member, but 3 members regarded them as highly relevant in the assessment of health status of arthritis patients. Ratings on the relevance of all 12 subscales of the CAIMS2 are shown in Table 1.
Table 1. Ratings by the expert panel on the relevance of the 12 subscales used in CAIMS2*
| ||Very good %||Good %||Fair %||Poor %||Very poor %|
|Walking and bending||33||50||17||0||0|
|Hand and finger function||33||50||17||0||0|
|Support from family and friends||17||33||33||17||0|
|Level of tension||17||33||33||17||0|
The expert panel rated 53 of the 56 items of the CAIMS2 as culturally relevant for Chinese arthritis patients. Among them, 36 items were rated as very good or good in cultural relevance by all members of the expert panel. Fifteen items were rated as very good or good in cultural relevance by more than 4 of the 8 members of the panel. Four items were rated as fair by more than 4 of the 8 panel members. Items 15, 45, and 55 were rated as poor by 2 of 8 panel members. The panel suggested modification of these questions so that they were more suitable for Hong Kong Chinese culture (Table 2). More than 4 of the 8 members of the expert panel commented that items 25, 30, and 31 in the questionnaire were only fairly relevant to Hong Kong culture. Items 2 and 3 were regarded as redundant in assessing mobility level (Table 3). Although most of the panel members rated the above 3 items as poorly relevant to Hong Kong and that items 2 and 3 were redundant, the investigators decided to keep these 5 items in the questionnaire for field testing. Subsequent analysis took these items into account and assessed whether the content validity could be improved by adding or removing some or all of them from the original questionnaire.
Table 2. Three items rated as poorly relevant by the panel that were modified
|Item no.||Original question||Changed to|
|15||Could you easily open a new jar of food?||Could you easily open a jar of food?|
|45||On the days that you did work, how often did you have to work a shorter day?||How often did you have to have sick leave?|
|55||How often did you feel that others would be better off if you were dead?||How often did you feel that you would be a burden on others due to arthritis?|
Table 3. Items rated as poorly relevant and redundant by the expert panel
|Item no.||Original question||Rationale|
|25||If you had the necessary transportation, could you go shopping for groceries without help?||A lot of people in Hong Kong do not require transportation to go shopping|
|30||How often did you have friends or relatives over to your home?||People in Hong Kong seldom invite their friends or relatives to their home|
|31||How often did you visit friends or relatives at their homes?||People in Hong Kong seldom visit their friends and relatives in their homes|
In addition to the questions altered, the expert panel suggested inclusion of 2 items relevant to the Chinese culture. Eating and the use of chopsticks are abilities highly valued by Chinese people. Thus, the following items were added: “Could you easily use chopsticks?” in the hand and finger function and “Did you need help in feeding?” in the self-care tasks.
The final version of CAIMS2 consisted of 59 items. All of the answering scales were rated as either good or very good by the expert panel. Due to the length of the questionnaire, sections on current level of function, problem areas, and areas patients wanted to have improvement were not included in CAIMS2.
Subjects (240 total; RA n = 81, OA n = 77, healthy subjects n = 82) were recruited for field testing. There were 71 men (29.6%) and 169 women (70.4%). The age of the RA subjects ranged from 22 to 72 (mean 48) years; OA subjects 46 to 83 (mean 65) years; and healthy subjects 19 to 82 (mean 36) years. The majority of the healthy subjects had completed 9 years or more formal education but only 69% of the RA subjects and 24% of the OA subjects had achieved such educational level.
Most of the RA and healthy subjects (RA 83%, healthy subjects 94%) could complete the CAIMS2 and the Hong Kong version of the WHOQOL–BREF without assistance. However, only 27% of all OA subjects were able to complete the questionnaire by themselves. The majority of the subjects who needed assistance to complete the questionnaire were illiterate. Of subjects older than 65 years, 72% needed assistance in completing CAIMS2, whereas 22% of the subjects younger than that age needed assistance. The majority of subjects older than 65 years had achieved less than 9 years of education. All the subjects who needed assistance in completing CAIMS2 had achieved less than 11 years of education. Of subjects having achieved 9 or fewer years of education, 66% needed assistance in completing CAIMS2. All the subjects who had achieved more than 11 years of education could complete the questionnaire independently.
The administration time for patients who were able to complete the questionnaire without assistance was 22.85 (SD = 7.96) minutes. This is comparable to the findings of Meenan et al (14).
Convergent and divergent validity.
There were significant correlations between the CAIMS2 arthritis pain subscale score and the pain VAS (r = 0.566, P = 0.001), total tender joint count (r = 0.311, P = 0.001), and total swollen joint count (r = 0.243, P = 0.001). No significant correlation was found between the CAIMS2 arthritis pain score and disease activity indicators, such as ESR and CRP. However, ESR and serum CRP levels correlated highly with each other (r = 0.527, P = 0.01). Laboratory findings also correlated significantly with total swollen joint count (ESR r = 0.325, P = 0.018; CRP r = 0.346, P = 0.012) and pain VAS score (ESR r = 0.335, P = 0.016). These results supported the validity of using the CAIMS2 to measure pain and severity but not the activity of arthritis.
Comparison of the CAIMS2 score and the functional scores showed significant negative correlations and supported that higher arthritis impact was associated with decreased function. Scores on the Barthel Index correlated highly with the self-care subscale (r = −0.552, P = 0.0001), work subscale (r = −0.399, P = 0.001), and mobility subscale (r = −0.361, P = 0.002) of the CAIMS2. There were also significant negative correlations between the Barthel Index score and mood (r = −0.250, P = 0.035), and grip strength (right hand) and support from family and friends (r = −0.299, P = 0.028). Significant negative correlations were also found between grip strength (right hand) and the CAIMS2 work (r = −0.334, P = 0.025), mobility (r = −0.345, P = 0.011), and hand and finger function (r = −0.276, P = 0.044) subscales; and grip strength (left hand) with work (r = −0.364, P = 0.014) and mobility (r = −0.309, P = 0.023) subscales. These results suggested a significant association between functional status and psychological well being.
Significant correlations were observed between WHOQOL–BREF physical domain scores and all of the CAIMS2 subscale scores, except support from family and friends. WHOQOL–BREF physical health had the highest correlation with the CAIMS2 arthritis pain score (r = −0.667, P = 0.000) and lowest correlation with self-care ability score (r = −0.137, P = 0.46). The WHOQOL–BREF psychological domain score correlated negatively with the CAIMS2 mobility, walking and bending, arm function, social activities, support from family and friends, arthritis pain, work tension, and mood subscale scores. The highest correlation was found between WHOQOL–BREF psychological domain score with tension (r = −0.245, P = 0.000) and mood subscale scores (r = −0.264, P = 0.000). The lowest correlation was found between WHOQOL–BREF psychological domain score with support from family and friends subscale scores (r = −0.159, P = 0.021). The WHOQOL social domain score correlated negatively with the CAIMS2 social activities (r = −0.291, P = 0.000), mood (r = −0.291, P = 0.000), tension (r = −0.263, P = 0.0001), support from family and friends (r = 0.246, P = 0.0001), and arthritis pain (r = −0.223, P = 0.001) subscale scores. Correlations between the CAIMS2 subscales and other disease activity assessment, functional assessment, and quality of life scores are summarized in Table 5.
Table 5. Correlations (r) between CAIMS2 scores and other disease assessments*
| ||Pain (VAS)||Total tender joints||Total swollen joints||Barthel Index||Grip (R)||Grip (L)||WHOQOL physical||WHOQOL psychological||WHOQOL social|
|Walking and bending||0.466†||0.393†||0.192||−0.182||−0.163||−0.208||−0.624†||−0.189†||−0.148‡|
|Hand and finger function||0.253‡||0.094||0.072||−0.112||−0.276‡||−0.205||−0.313†||−0.122||−0.170‡|
|Support from family and friends||0.094||0.105||0.179||0.084||−0.299‡||−0.232||−0.104||−0.159‡||0.246†|
The above results supported the hypothesis that a higher correlation between the instrument score and other assessments that measure the same concepts is expected and that indicators of different health concepts or domains yield a lower correlation.