Development and Evaluation of a Single Value Score to Assess Global Range of Motion in Juvenile Idiopathic Arthritis

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1 Arthritis & Rheumatism (Arthritis Care & Research) Vol. 47, No. 4, August 15, 2002, pp DOI /art , American College of Rheumatology ORIGINAL ARTICLE Development and Evaluation of a Single Value Score to Assess Global Range of Motion in Juvenile Idiopathic Arthritis HEATHER EPPS, 1 MIKE HURLEY, 2 AND MARTIN UTLEY 1 Objectives. To develop a global range of motion score (GROMS) and to investigate the association between this newly developed measure of joint range of motion and physical function in children with active juvenile idiopathic arthritis (JIA). Methods. Two scales were calculated, 1 measuring 56 selected joints and 1 measuring 10 joints assessed as important to function by experts from the British Paediatric Rheumatology Group. These were in 50 patients with JIA whose disability was assessed using the Child Health Assessment Questionnaire (CHAQ). Results. The GROMS measuring all joints and the GROMS measuring 10 joints closely agreed with each other, and both GROMS correlated significantly with the CHAQ (r 0.52 and 0.62, respectively). Conclusion. The 10-joint GROMS is a simple, easy-to-use tool that measures overall change in joint range of motion that affects physical function in JIA. KEY WORDS. Juvenile idiopathic arthritis; Range of motion; Function; Outcome. INTRODUCTION Approximately 10 in every 100,000 children and adolescents in the UK have juvenile idiopathic arthritis (JIA); approximately 30% of patients have active disease after 10 years, and many have disability continuing into adulthood (1 4). Anatomic, physiologic, and emotional abnormalities occur as a direct result of disease (5,6), leading to a loss of joint range of motion (ROM) and restricted functional performance (7). In 1997, a core set of outcome variables for the assessment of JIA was identified. A definition of clinically important improvement was then developed that could be used as a single measure of efficacy in JIA clinical trials (8,9). One of these variables was the number of joints with Ms Epps work was supported by the Arthritis Research Campaign UK. 1 Heather Epps, MSc, MCSP, SRP, Grad Dip Phys, Martin Utley, BSc, PhD: University College London, United Kingdom; 2 Mike Hurley, PhD, MCSP, SRP: Kings College London, United Kingdom. Address correspondence to Heather Epps, MSc, MCSP, SRP, Grad Dip Phys, Centre for Rheumatology, University College London, Arthur Stanley House, Tottenham Street, London W1P 9PG, UK. heather@hepps. fsnet.co.uk. Submitted for publication August 19, 2001; accepted in revised form December 29, loss of ROM, whereby joint motion is defined as limited or not limited. Therefore a loss or gain in motion, which is important to function, could be overlooked when using these criteria. Furthermore, an improvement in this variable was defined as a reduction by more than 30% in the number of joints with limited ROM, which actually means an improvement in 2 (50%), 2 (33%), or 3 (43%) joints if a patient has 4, 6, or 7 joints affected, respectively. We believe there is a need for a more meaningful and robust measure of ROM that is associated with function (10,11) and is used in the evaluation of drug efficacy, physical therapy, and occupational therapy (12 14). However, without a method to assess overall joint ROM that is related to function or disease activity and is sensitive to important clinical change, these measurements are of little practical use. Several measures of function are available for this population (15); however, measuring joint ROM is time consuming if multiple joints are involved. A single, reliable, valid, and responsive measure of overall joint ROM would be useful in the assessment of clinical change and the evaluation of treatments, and should recognize that certain key joints are more important to functionality than others. Two evaluation techniques are available to measure overall ROM in adult and pediatric rheumatology populations. The Joint Alignment and Motion (JAM) scale was developed for use in adults (16), and although it correlates with the Child Health Assessment Questionnaire (CHAQ) 398

2 Development and Evaluation of a Global ROM Score in JIA 399 Table 1. Calculating a GROMS using all joint movements except the lumbar and thoracic spine* Joint movement A Measured B Normative C A B D Mode E C D Cx spine extension Cx spine rotation Shoulder flexion Shoulder abduction Shoulder ER Shoulder IR Elbow extension Elbow flexion R/U supination R/U pronation Wrist flexion Wrist extension MCP (2 5) PIP (2 5) DIP (2 5) Thumb flexion Thumb abduction Thumb DIP Hip flexion Hip extension Hip abduction Hip IR Hip ER Knee flexion Knee extension Ankle dorsiflexion Ankle plantarflexion Sum of E * GROMS GROMS global range of motion scale; Cx cervical; ER external rotation; IR internal Sum of D 110 rotation; MCP metacarpophalangeal; PIP proximal interphalangeal; DIP distal interphalangeal. (17) in polyarticular JIA, it is insensitive to important clinical change (6). The Escola Paulista de Medicina (EPM- ROM) scale measures ROM in 10 specific joints, and correlates with the CHAQ and number of joints with loss of ROM in JIA (18). However, the EPM-ROM has not been validated against a scale that incorporates all joint movements, so it is unknown if information is lost when using this measure. Furthermore, responsiveness to change over time of the EPM-ROM has not been assessed. Both the JAM and EPM-ROM scales use predetermined minimum and maximum degrees of motion to score joint range into different categories of limitation of movement. This could lead to reduced sensitivity due to ceiling and floor affects, and inter- and intra-rater variability. In addition, a gain or loss of only a few degrees of motion could change the category of a joint movement, affecting the overall score. This article describes the development of a global joint range of motion score (GROMS) in which scores are weighted to reflect the importance of individual movements to function in JIA. To ensure that this instrument measures overall ROM and reflects its association with function, several tests were undertaken to determine its validity. We describe how content validity (that the joint movements are a well-balanced sample of overall joint ROM affecting function in JIA) and concurrent validity (that the GROMS correlates with other well-validated measures of function, i.e., the CHAQ) (19) were evaluated, and we show that the GROMS has high collinearity with other ROM measures. PATIENTS AND METHODS Development of the GROMS. Two GROMS were developed; one used measurements weighted for function and included 56 key joint movements, the second used movements identified as essential to function. All members of the British Paediatric Rheumatology Group were sent a questionnaire asking them to rank order 56 individual joint movements on a scale of 0 to 5; 0 not at all important, 5 essential for key functional activities in children with JIA. Of these experts, 76% responded: 21 physicians, 22 physiotherapists, 6 occupational therapists, and 3 specialist nurses. Each individual joint movement was then assigned a weight from 0 to 5, which reflected its functional importance determined by using the most frequently reported score (mode) from the experts responses (Table 1). The 10 joint movements most frequently ranked as essential to function were elbow flexion, wrist extension, metacarpophalangeal (MCP) movement, proximal interphalangeal (PIP) movement, thumb flexion, thumb abduction, hip flexion, hip extension, knee flexion, and knee extension (Table 2).

3 400 Epps et al Table 2. Calculating the reduced-item GROMS using the 10 movements ranked most frequently as essential to function by the experts (mode 5)* Joint movement A Measured movement B Normative movement C A B D Mode (weight) E C D Elbow flexion Wrist extension MCP (average) PIP (average) Thumb flexion Thumb abduction Hip flexion Hip extension 150 (15) 155 (20) Knee flexion Knee extension 145 (0) 145 (0) Sum of E * GROMS Loss of hip and knee extension are by taking loss of motion from normative range Sum of D 10 of motion (full flexion to extension) to prevent negative results. All weights are the same and therefore 1. GROMS global range of motion scale; MCP metacarpophalangeal; PIP proximal interphalangeal. Patients. Fifty patients were recruited from 3 pediatric rheumatology centers; their clinical characteristics are presented in Table 3. All subjects were diagnosed with JIA of more than 6 months duration, had at least 1 active joint (20), and had loss of motion in more than 1 joint. Subjects with previous or ongoing medical interventions, surgery, or other conditions that might affect joint ROM or function were excluded. Informed consent was obtained from each subject s parents and informed assent from each adolescent. Procedure. The principal investigator (HE) the active-assisted ROM of all patients joints using a goniometer (Whitehall Manufacturing, UK). Standardized goniometer and subject positions were used (21). Parents completed a CHAQ (17) during the initial visit. Statistical analysis. The GROMS were calculated as follows (see Tables 1 and 2): Table 3. Subject characteristics* Female (n 28) Male (n 22) Age, years 12 (4 18) 12 (8 18) Disease duration, years 5 ( ) 5 ( ) Systemic course 1 3 Polyarticular 17 6 Oligoarticular 4 1 Ext oligoarticular 4 2 Enthesitis-related arthritis 2 9 Psoariatic 0 1 * Values are mean (range). Disease course after 6 months is presented as opposed to disease onset. Ext extended. 1) The ROM at an individual joint was, and the mean of the right and left movements was calculated (column A). 2) The normative ROM at an individual joint for the subject s age was recorded from Norkin and White (column B) (21). 3) The ratio of the score and expected normative score was calculated (column A column B column C). 4) To obtain a joint movement score weighted for function, the ratio obtained in column C was multiplied by the experts evaluation of the importance of a movement (column C column D column E). 5) To obtain a total score out of 100, the individual weighted joint scores were summed, multiplied by 100, and divided by the sum of the weights used. Table 1 demonstrates an example of calculating the GROMS when all joints are (thoracic and lumbar spine movements were excluded because there is no accepted standardized form of measurement). Table 2 demonstrates an example of calculating the GROMS when only the 10 movements with a modal value of 5 (e.g., essential for function) are used. Spearman s rank order correlation coefficients were used to calculate any relationship between the CHAQ, number of joints with loss of motion, and GROMS (22). A Student s two-tailed t-test was used to detect any difference between the 2 GROMS scores, to determine if information was lost when only the movements essential to function were. RESULTS From the survey of expert opinion, 10 movements were identified as essential to function (e.g., modal value 5): elbow flexion, wrist extension, MCP movement, PIP movement, thumb flexion, thumb abduction, hip flexion, hip extension, knee flexion, and knee extension. The measures of all joint ROM (r 0.52) and of the 10 movements rated essential to function (r 0.62) were inversely related to the CHAQ, which scores 8 areas of subjective function to give a disability index of 0 no disability to

4 Development and Evaluation of a Global ROM Score in JIA 401 Table 4. Spearman s rank order correlation coefficients* 3 maximum disability (P 0.01; Table 4). The numbers of joints with loss of ROM were inversely related to both GROMS, (r 0.73 and 0.74, P 0.01; Table 4). The GROMS measuring all joint ROM and only the 10 movements rated essential to function were in agreement, as there was no statistical difference between these 2 measures (t 0.017, P 0.2). DISCUSSION CHAQ GROMS 10 joints Number of joints with loss of range of motion GROMS all joints CHAQ GROMS 10 joints * Correlation coefficients between the GROMS measuring all movements; the GROMS measuring 10 movements essential to function in JIA; the number of joints with loss of range of motion, and function (CHAQ). GROMS global range of motion scale; CHAQ Child Health Assessment Questionnaire. P This article describes the development of a single score GROMS to assess change in joint ROM in JIA. It is simple and easy to apply in the clinical setting, it is related to function, and it does not lose important information if only 10 movements rated as essential to function are. The GROMS calculated by measuring the 10 joint movements rated by the experts as essential to function (the 10-joint GROMS) and the GROMS calculated by measuring all joint ROM were moderately correlated with function, and there was no statistical difference between the scores. Measuring 10 movements, and yet still retaining the same information as all joints being, has important clinical implications: it reduces the time needed to assess ROM and simplifies the calculation of a single outcome score. Calculating the GROMS measuring all joint ROM is time consuming and has a greater potential for errors than when only 10 joint movements are. Calculating the 10-joint GROMS takes only a few minutes to complete. Although the reliability of any ROM score may be compromised by inter- and intrarater inconsistencies in goniometric measurements, individual errors have less impact when using a continuous scale such as the GROMS. To determine the content validity of the 10-joint GROMS, it was necessary to establish that the 10 movements selected presented a well-balanced sample of all joint movements, when related to function (19). Seven of the movements selected for the 10-joint GROMS (wrist extension, thumb flexion and abduction [circumduction], MCP flexion, PIP flexion, hip flexion, and knee flexion) were the same as those identified by Bradley et al (10) as related to function in adults with arthritis (P 0.01). However, only wrist and knee extension were selected by Len et al (18) as related to function in JIA. This may be explained by the methods employed by Len et al: they the joints most frequently affected by disease, as opposed to those that may specifically affect function. Furthermore, they did not validate the movements selected against a scale incorporating all joint movements. A number of studies have demonstrated an association between ROM and function (10,11,16,18). The significant relationship between GROMS and CHAQ reported in this study corroborates the association between ROM and function, and thus supports the concurrent validity of the GROMS. This validity is further demonstrated by the high correlation of the GROMS with the number of joints with loss of ROM. The correlation between the CHAQ and both GROMS is moderate, which is not unexpected because many patients report a single physical problem that is clinically important to them (e.g., dressing), but may not result in a high score on a broad-based disability index such as the CHAQ (3). The population studied was restricted to those patients with active disease. Patients in remission or those with long-standing changes in ROM may have a low disability index because they have learned compensatory movements. Although considered the gold standard, there may be confounding variables affecting function that are not detected using the CHAQ (which measures the parent s or child s perceptions of difficulty, and can be influenced by emotional and social factors), leading to discordance with other measures that affect function (23). In addition, function is also affected by variables other than ROM, e.g., motivation, pain, and muscle strength. The correlations reported in the present study are comparable to those previously reported between the CHAQ and number of joints with limited ROM, which is a validated measure of movement (24). The relationship between the 10- joint GROMS and function supports the use of this instrument to measure joint ROM that affects function. The GROMS has limitations and may be inappropriate for some patients with JIA. It is insensitive to change in ROM when disease does not affect any of the 10 joints by the 10-joint GROMS, or if the patient s problems are predominantly axial, e.g., spondylarthropathies. In addition, the results of this study relate to subjects who were recruited from specialist centers, skewing data towards normative ROM with few patients having gross losses of ROM. However, this is representative of these patient populations because of improvements in drug management. It is not known if patients with uncontrolled disease or severe loss of joint movement demonstrate an association between the GROMS and CHAQ. Generalizing these results to the entire population should therefore be viewed with caution. The present study used the self-report CHAQ as a measure of function. However, quantitative measures, such as the Juvenile Arthritis Functional Assessment Scale (25), an objective measure of function, may reflect an association between the GROMS and function more accurately. Reliability and sensitivity of the 10-joint GROMS have not been tested. It is not known if it will measure small, clinically important changes over time. Future studies are planned to assess the reproducibility of the relationship

5 402 Epps et al between the 10-joint GROMS and CHAQ, and the responsiveness of the 10-joint GROMS to change in function and disease activity over time in JIA. It may also be possible to ascertain the predictive validity of this measure, i.e., how well it forecasts changes in functional performance and level of impairment. These studies are necessary before the 10-joint GROMS can be used prospectively. In summary, the 10-joint GROMS is a practical, easy-touse assessment of overall joint ROM that reflects selfreported functional ability. This provides useful information that can complement other measures when assessing the degree of impairment, the effectiveness of treatment regimes, and disease progression in JIA. ACKNOWLEDGMENTS We are grateful to the members of the British Paediatric Rheumatology Group and the patients from the Middlesex Adolescent Unit, University College London Hospitals, Great Ormond Street and Birmingham Children s Hospitals whose collaboration made this research possible. We also wish to thank the 2 anonymous reviewers of this manuscript for their useful suggestions. REFERENCES 1. David J, Cooper C, Hickey L, Lloyd J, Dore C, McCullough C, et al. The functional and psychological outcomes of juvenile chronic arthritis in young adulthood. Br J Rheumatol 1994; 33: Zak M, Pedersen FK. Juvenile chronic arthritis into adulthood: a long-term follow-up study. Rheumatology 2000; 39: Miller M, Kress AM, Berry CA. Decreased physical function in juvenile rheumatoid arthritis. Arthritis Care Res 1999;12: Ruperto N, Levinson JE, Ravelli A, Shear ES, Tague BL, Murray K, et al. 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