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Can Hand Assessments Designed for Persons with Scleroderma Be Valid for Persons with Rheumatoid Arthritis?

To the Editor:

Two recently developed assessments have been designed for persons with scleroderma. One, the UK Scleroderma Functional Score (UKFS) or Scleroderma Functional Assessment Questionnaire (Table 1), is a self-report of functional ability¹ and has been shown to be reliable and valid for persons with scleroderma^1-3. The other assessment is the Hand Mobility in Scleroderma Test (HAMIS)^4,5. The HAMIS is a performance test of joint motion (Table 1) and has also been shown to be reliable and valid for persons with scleroderma. Since rheumatoid arthritis (RA) results in deformities of the hand, as does scleroderma, we wondered if the SFAQ and the HAMIS were valid assessments to measure hand function and joint motion in persons with RA. We compared SFAQ and HAMIS scores to other self-reports and performance based tests of hand function and range of motion in persons with RA.

Table 1. Description and descriptive statistics for the performance of 40 subjects on the UKFS, HAMIS, DHI, HAQ, AHFT, and KFT.

A convenience sample of 40 subjects who had been diagnosed with RA according to the American College of Rheumatology criteria⁶ participated in this study. The mean age of subjects was 49.5 years (range 22-76 yrs), with a mean disease duration of 13.1 years (range 1-42 yrs). Subjects consisted of 34 women and 6 men. Thirty-eight subjects were right-handed, one was left handed, and one reported being ambidextrous.

Subjects were administered the following assessments: the UKFS¹, the HAMIS^4,5, the Duruöz Hand Index (DHI; also referred to as the Cochin Scale)⁷, the Health Assessment Questionnaire (HAQ)⁸, the Arthritis Hand Function Test (AHFT)⁹, and the Keital Functional Test (KFT)¹⁰. The concepts measured, question structure, and possible range of scores for each assessment are shown in Table 1. The UKFS, DHI, and HAQ are all self-reports, while the HAMIS, AHFT, and KFT are performance based tests.

Table 1 also shows the means and standard deviations for the 40 subjects on the UKFS, HAMIS, DHI, HAQ, AHFT, and KFT. Spearman rho correlation coefficients were calculated to examine the concurrent validity of the UKFS and HAMIS with the DHI, HAQ, and KFT. Table 2 shows good to excellent correlations of the UKFS with the DHI and the HAQ¹¹. Fair to moderate correlations were ascertained between UKFS and the HAMIS, AHFT, and KFT¹¹. For the HAMIS, only the correlation with the KFT was in the good to excellent range; correlations with the other tests were in the fair to moderate range.

Table 2. Spearman rho correlation coefficients for the SFAQ and HAMIS (n = 40).

One way to determine validity of instruments is to correlate scores with variables known to have a converging relationship and with variables considered to have a moderate to minimal or divergent relationship. Thus, the UKFS would be expected to have higher relationships with the DHI and HAQ and less strong relationships with the measures of joint motion (HAMIS, KFT), hand strength, and dexterity (AHFT). Indeed, the strongest correlations for the UKFS were with the other self-reports, the DHI and HAQ, which have similar questions. However, the correlations with the sections on the AHFT are good, suggesting that perceptions of ability do reflect actual hand skills. The lower correlations between the UKFS scores and the HAMIS and KFT suggest a divergent relationship, and are not surprising as these 2 tests correlated highly with each other and assess joint motion rather than hand function. Thus, the findings support the convergent validity of the HAMIS. On the other hand, the HAMIS only moderately correlated with the 3 self-reports of function. The slightly stronger correlations between the HAMIS and scores from the AHFT suggest that range of motion is related to hand strength and dexterity. However, from the moderate correlations, it seems that measures of joint motion, strength, and dexterity are not synonymous with hand function. These findings are similar to other studies with persons with RA, which found that self-reports of hand function had convergent relationships with other self-reports of functional ability, but divergent relationships with variables such as pain, stiffness, tenderness and swelling, and joint motion^7,12,13. The divergent relationships suggest that measures of impairment such as joint motion, hand strength, and dexterity do not adequately address hand function, and impairment measures should be accompanied by assessments of hand function. Thus, the UKFS and HAMIS complement each other and are simple and easy to administer. They are valid for use with persons with RA and may be useful as outcome measures of hand function and joint motion.

JANET L. POOLE, PhD, OTR/L, Occupational Therapy Graduate Program, e-mail: jpoole@salud.unm.edu; KENNETH J. CORDOVA, OTS, Department of Pediatrics, MSC09 5240, University of New Mexico, Albuquerque, New Mexico 87131-001, USA.

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