Hand Function Test

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ORIGINAL ARTICLES Reliability and Validity of the Arthritis Hand Function Test in Adults with Systemic Sclerosis (Scleroderma) Janet L. Poole, Melody Gallegos, and Sandra O’Linc Objective. To determine the interrater and test– retest reliability and validity of the Arthritis Hand Function Test (AHFT) in persons with systemic sclerosis. Methods. Interrater reliability of the AHFT was established by two raters independently scoring the performances of 20 women with systemic sclerosis. The same group of subjects was tested again 7–10 days later to determine test–retest reliability. Concurrent validity was established by the subjects’ selfreports of their abilities to perform activities of daily living as measured by the Health Assessment Questionnaire and the Arthritis Impact Measurement Scales 2 (AIMS2). Results. All of the items had excellent interrater intraclass correlation coefficients (ICC ⫽ 0.99 –1.00). The ICCs for test–retest reliability were in the excellent (ICC ⫽ 0.80 – 0.97) range for most of the items and moderate (ICC ⫽ 0.57– 0.73) for the others. Most of the items were moderately correlated with items on the AIMS2 (r ⫽ 0.45– 0.69). Janet L. Poole, PhD, OTR/L, Assistant Professor, Occupational Therapy Program, Department of Orthopaedics, University of New Mexico, Albuquerque; Melody Gallegos, OTR/L, Occupational Therapist, Albuquerque Public Schools, Albuquerque, New Mexico; and Sandra O’Linc, OTR/L, Fredonia, Pennsylvania. Address correspondence to Janet L. Poole, PhD, OTR/L, Occupational Therapy Program, University of New Mexico, Health Sciences and Services Building, Room 215, Albuquerque, NM 87131-5641. Submitted for publication July 13, 1999; accepted in revised form January 13, 2000. © 2000 by the American College of Rheumatology. 0893-7524/00/$5.00 Conclusion. The results from this study suggest that the AHFT is a reliable and valid test to measure hand function in persons with systemic sclerosis. Key words. Hand function; Systemic sclerosis; Activities of daily living. INTRODUCTION Systemic sclerosis (scleroderma) is a multisystem disease characterized by thickening of the skin, vascular insufficiency, and fibrotic changes in the muscles, joints, and internal organs. In the hand, the thickening of the skin can lead to contractures in the fingers in which there is a loss of flexion at the metacarpophalangeal joints, loss of extension at the proximal interphalangeal joints, and loss of abduction of the thumb (1,2). Poole and colleagues have shown that hand involvement in systemic sclerosis leads to functional disability (3–5). However, measures of hand involvement used in the above studies consisted of strength and range of motion rather than tasks used in daily living. In addition, during the time in which data were collected for these studies, there was no assessment of hand function in which the hands were used bilaterally. Several assessments have been developed since the studies mentioned above, such as the Grip Ability Test (6), the Observed Hand Function Test (7), the Sequential Occupational Dexterity Assessment (8), and the Arthritis Hand Function Test (AHFT) (9,10). Of these, the AHFT has the strongest published evidence of reliability and validity. The AHFT is an 69 70 Poole et al 11-item standardized test that assesses people’s abilities to use their hands for daily tasks. The hand strength items measure grip using an adapted sphygmomanometer and pinch strength with a pinch meter. The mean of 3 trials is recorded as the score for each item. The dexterity section consists of a pegboard test. The score is the time required to place and remove 9 pegs from a pegboard. The applied dexterity section consists of 5 timed functional items yielding separate scores: fasten and unfasten 4 buttons, lace a shoe and tie a bow, pin and unpin 2 safety pins in a cloth, pick up and manipulate 4 coins into a slot, and cut a piece of putty with a knife and fork into 4 pieces. The applied strength section consists of 2 items: lift a tray filled with cans of soup and pour a glass of water from a pitcher with a measured volume of water. The AHFT demonstrated high interrater reliability (r ⫽ 0.89 –1.00) and moderate test–retest reliability (r ⫽ 0.53– 0.95) in a sample of 20 subjects with rheumatoid arthritis (RA) (10) and in a sample of 26 subjects with osteoarthritis (OA) (11). The validity of the applied dexterity sections for subjects with RA was established by correlating the scores with the dexterity scores from the Arthritis Impact Measurement Scales (r ⫽ 0.71) and the Jebsen Hand Function Test (r ⫽ 0.63) (10). Validity of the AHFT for subjects with OA was established by correlating the scores with scores of physical activities of daily living (r ⫽ 0.40 – 0.69) and instrumental activities of daily living (r ⫽ 0.46 – 0.75) (11). Interrater reliability of selftrained raters ranged from 0.45 to 0.90 (12). Because the AHFT has been shown to be reliable and valid with two other rheumatic diseases, it may be appropriate for use in measurement of hand function in persons with systemic sclerosis. Thus, the purpose of this study was 2-fold: 1) to investigate the interrater reliability and test–test reliability of the AHFT in persons with systemic sclerosis, and 2) to examine the concurrent validity of AHFT in persons with systemic sclerosis. PATIENTS AND METHODS Subjects. Twenty women with systemic sclerosis (SSc) who fulfilled the American College of Rheumatology criteria for SSc (13) were recruited for the study. The sample was one of convenience. Eleven subjects were classified as having limited SSc, 6 as diffuse SSc, and 3 were unclassified. The ages of the subjects ranged from 31 to 75 years (mean 50.35 years, SD 12.05). Disease duration ranged from 3 months to 32 years (mean 7.5 years, SD 7.73). All Vol. 13, No. 2, April 2000 subjects except for one were right dominant. Once a subject agreed to be in the study, she was contacted by telephone, and two testing times were scheduled. Subjects were tested in their own homes at their convenience. The mean pain score as measured by the Health Assessment Questionnaire (HAQ) visual analog scale (14) was 1.12, and the mean pain score as measured by the Arthritis Impact Measurement Scales 2 (AIMS2) pain questions (15) was 4.87, indicating mild to moderate pain. All subjects gave informed consent. Procedure. Interrater reliability of the AHFT was assessed by having two independent raters score each subjects’ performance during the initial test session. To assess test–retest reliability, subjects were tested again 7–10 days after the AHFT was first administered. To assess concurrent validity of the AHFT, subjects completed self-report instruments regarding their abilities to perform activities of daily living. The instruments used were the disability scale on the HAQ and the physical component of the AIMS2. The disability scale on the HAQ (14) was designed to measure functional ability and patient outcome in rheumatic disease patients. It consists of 8 categories of daily living (dressing and grooming, arising, eating, walking, hygiene, reach, grip, and outside activity). Each question is scored as: without difficulty ⫽ 0, with difficulty ⫽ 1, with help from another person or with a device ⫽ 2, and unable to do ⫽ 3. The highest score for any individual question in each category determines the score for that category. A disability scale index is calculated by adding the scores for each of the categories and dividing by the number of categories answered. Test– retest reliability for the disability scale index was reported to be 0.98 (14). The AIMS2 was designed to measure health status (15). It consists of 57 questions spread over 12 scales. Six of these scales are combined to form the AIMS2 physical component: mobility, walking and bending, hand and finger function, arm function, self-care, and household tasks. Each question on the AIMS2 is scored from 1 (always or all days) to 5 (never or no days); however, the response arrangements are mixed so that the last response will not always indicate poor health status. Internal consistency alphas exceed 0.70 in subjects with both RA and OA. Test–retest reliability intraclass correlation coefficients were equal to or greater than 0.80 for all scales except work, and were greater than 0.90 for 6 of the 12 scales (15). Arthritis Hand Function Test in SSc 71 Arthritis Care and Research Table 1. Descriptive statistics for the performance of 20 subjects with systemic sclerosis on the Arthritis Hand Function Test (AHFT) Range AHFT item* Mean Standard deviation Minimum Maximum Grip strength, RH (mm Hg) Grip strength, LH (mm Hg) Two point pinch, RH (lb) Two point pinch, LH (lb) Three point pinch, RH (lb) Three point pinch, LH (lb) Peg dexterity, RH (sec) Peg dexterity, LH (sec) Shoe lacing (sec) Buttons (sec) Safety pins (sec) Cutting with knife and fork (sec) Manipulating coins (sec) Lifting cans (no. of cans) Pouring water (ml) 194.50 191.60 9.43 9.09 11.09 10.96 24.37 25.93 48.15 30.92 25.38 44.20 15.13 10.50 1870.0 73.50 72.70 2.98 2.50 4.27 3.96 7.87 9.09 23.02 14.36 9.35 33.77 10.10 2.43 292.2 44.00 53.00 3.50 3.83 4.83 4.83 18.00 19.00 31.00 16.00 17.00 13.00 7.00 4.00 1200.0 297.33 296.33 16.50 16.67 17.33 20.83 46.00 46.00 120.00 60.00 41.00 114.00 59.00 12.00 2000.0 * RH ⫽ right hand; LH ⫽ left hand. RESULTS Descriptive statistics for the 20 subjects’ performances on the AHFT are reported in Table 1. These mean scores suggest mild to moderate impairment of hand function, especially applied dexterity, when the scores are compared with scores obtained from adults who are nondisabled, as reported in the AHFT manual (9). Intraclass correlation coefficients (ICCs) type 2.1 and 3.1 were calculated to estimate interrater and test–retest reliability (Table 2). Fleiss (16) states that values greater than 0.75 represent excellent agreement, values below 0.40 represent poor agreement, and values between 0.40 and 0.75 represent moderate agreement. All of the AHFT items had excellent interrater ICCs (ICC ⫽ 0.99 –1.00). The ICCs for test– retest reliability were excellent for most of the items (ICCs ⫽ 0.80 – 0.97) and moderate for the others (ICCs ⫽ 0.57– 0.73). Pearson’s r correlation coefficients were calculated to estimate the concurrent validity of the AHFT with both the HAQ and the AIMS2. Table 3 shows that grip and pinch strength correlations were not significantly correlated with either of the self-report measures. All of the dexterity, applied dexterity, and applied strength items were significantly correlated with scores on the HAQ, but only right hand peg dexterity, cutting with the knife and fork, manipulating coins, and the two applied strength items correlated with scores on the AIMS2. Because both the HAQ and the AIMS2 are widely used measures of health status, we expected similar results for the items. When this did not occur, we used Spearman’s correlations to examine the relation between the HAQ and AIMS2 (r ⫽ 0.697, P ⬍ 0.001). The pain scales were also highly correlated (r ⫽ 0.896, P ⬍ 0.0001). DISCUSSION The results obtained from this study support the use of the AHFT with persons who have SSc. The Table 2. Interrater and test–retest reliability for the Arthritis Hand Function Test (AHFT), intraclass correlation coefficients (ICCs) AHFT item* Interrater ICC Test–retest ICC Grip strength, RH Grip strength, LH Two point pinch, RH Two point pinch, LH Three point pinch, RH Three point pinch, LH Peg dexterity, RH Peg dexterity, LH Shoe lacing Buttons Safety pins Cutting with knife and fork Manipulating coins Lifting cans Pouring water 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 1.00 1.00 0.95 0.97 0.57 0.84 0.85 0.90 0.92 0.68 0.94 0.95 0.72 0.73 0.80 0.93 0.67 * RH ⫽ right hand; LH ⫽ left hand. 72 Poole et al Vol. 13, No. 2, April 2000 Table 3. Relationships between Arthritis Hand Function Test (AHFT) and self-reports of activities of daily living* AHFT item HAQ P AIMS2 P Grip strength, RH Grip strength, LH Two point pinch, RH Two point pinch, LH Three point pinch, RH Three point pinch, LH Peg dexterity, RH Peg dexterity, LH Shoe lacing Buttons Safety pins Cutting with knife and fork Manipulating coins Lifting cans Pouring water ⫺0.35 ⫺0.34 ⫺0.32 ⫺0.32 ⫺0.40 ⫺0.36 0.54 0.46 0.50 0.59 0.53 0.61 0.73 ⫺0.62 ⫺0.66 NS NS NS NS NS NS 0.013 0.040 0.023 0.007 0.017 0.004 0.000 0.003 0.001 ⫺0.29 ⫺0.24 ⫺0.19 ⫺0.31 ⫺0.24 ⫺0.28 0.45 0.21 0.24 0.40 0.31 0.49 0.46 ⫺0.66 ⫺0.69 NS NS NS NS NS NS 0.048 NS NS NS NS 0.030 0.041 0.002 0.001 * Pearson’s r. HAQ ⫽ Health Assessment Questionnaire; AIMS2 ⫽ Arthritis Impact Measurement Scales 2; RH ⫽ right hand; LH ⫽ left hand; NS ⫽ not significant. excellent ICCs for interrater reliability reported in this study were to be expected, as the items lend themselves to consistency by reading a meter or stopwatch and by counting the number of cans or milliliters of water. Excellent ICCs were also reported in studies involving subjects with RA (10) and OA (11). These two studies also reported perfect correlations for lifting cans and pouring water. Moderate test–retest reliability was obtained. It is unclear why pouring water and left hand peg dexterity had lower ICCs. Backman et al (10) also reported a lower ICC for left hand peg dexterity with subjects with RA. Overall, scores did tend to be lower at time 2. The raters reported that subjects seemed to not try as hard. It is also interesting that the right hand correlations for grip and pinch were not as high as those for the left hand, since all subjects except one were right handed. Scores on the AHFT also correlated with scores on the disability scale index on the HAQ and the physical component on the AIMS2 to determine relationships between hand function and performance of activities of daily living. None of the strength items except the applied items correlated significantly with HAQ and AIMS2 scores. However, in subjects with RA (10) and OA (11), these strength measures were significantly correlated with self-report of ability to perform self-care activities of daily living and instrumental activities of daily living. This discrepancy may be due to the findings that the subjects with SSc were stronger compared with the subjects who had RA and OA. In healthy subjects with nor- mal strength, grip and pinch strength did not predict ability to open household containers (17). It is interesting that more items on the AHFT correlated significantly with the HAQ than the AIMS2. The HAQ disability scale and the physical component of the AIMS2 have similar questions, although the HAQ asks about difficulty performing tasks while the AIMS2 asks about the frequency of ability. In this study, the moderate and significant correlations between the applied dexterity and strength items suggest a relationship between hand function as measured by the AHFT and performance of activities of daily living in persons with SSc. Compared with the AHFT descriptive statistics for subjects with RA (12) and OA (11), subjects with SSc have stronger hand strength but are slower with dexterity items. Thus, hand function, especially applied dexterity, seems affected by SSc. In conclusion, the AHFT appears to be a reliable and valid test of hand function in persons with SSc. 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