Reliability and sensitivity to change of various measures of hand function in relation to treatment of synovitis of the metacarpophalangeal joint in rheumatoid arthritis

P. H. Goossens, B. Heemskerk, J. van Tongeren, A. H. Zwinderman1, T. P. M. Vliet Vlieland and T. W. J. Huizinga

Department of Rheumatology and
1 Medical Statistics, Leiden University Medical Centre, The Netherlands


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Objectives. The reliability and discriminative capacity of hand function tests were studied in order to obtain tests suitable for the evaluation of local treatment of an arthritic metacarpophalangeal (MCP) joint.

Methods. To assess reliability, hand function tests were measured twice without local treatment of the MCP in 25 patients with rheumatoid arthritis (RA). The discriminative capacity of the hand function tests with respect to the results of intra-articular corticosteroid injection was assessed in 28 RA patients with synovitis of an MCP joint. Thereafter, a randomized, observer-blind treatment study was performed in 21 RA patients with synovitis of an MCP joint; 10 of the patients were treated.

Results/Conclusions. This study showed that the efficacy of treatment of an MCP joint can be measured by several reliable and discriminative parameters: passive flexion, the Ritchie pain score, swelling, the Arthritis Impact Measurements Scales question about buttoning clothes, and visual analogue scale questions about the activity of the disease and swelling of the joint.

KEY WORDS: Rheumatoid arthritis, MCP joint, Hand function, Corticosteroids, Impairment, Disability.


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Approximately 65% of rheumatoid arthritis (RA) patients suffer from synovitis of a metacarpophalangeal (MCP) joint. Local treatment of an inflamed joint may be considered, although there are very few data on the short- and long-term effects of these treatments. The progression of bone erosions and absence of joint swelling are measures of the long-term efficacy of local therapy of an arthritic MCP joint. The aim of this study was to investigate which clinical parameters are best suited to the evaluation of the short-term efficacy of local therapy. The reproducibility of a number of hand function tests was assessed in 25 patients with RA. The discriminative capacity of the hand function tests was assessed after treatment of synovitis of an MCP joint with intra-articular corticosteroids.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Patients
Patients with RA [1] visiting the out-patient department or hospitalized at the Department of Rheumatology of the Leiden University Medical Centre were invited to participate. Patients who had undergone a surgical procedure on the hand or had received local treatment of the MCP joint within 3 months before the start of the study were excluded.

Reliability
To assess the reliability of the tests, MCP joints 2 and 3 of the right hand of 25 hospitalized patients were examined on two occasions within 2 weeks at approximately the same time of day. The MCP joints were not treated locally during this period.

Discriminative capacity
Open treatment study.
To assess the discriminative capacity of the tests with respect to treatment, 28 patients visiting the out-patient department with synovitis of MCP joint 2 or 3 were treated with intra-articular corticosteroids. Their hand function was assessed immediately before and 4–10 days after the injection.

Randomized observer blind treatment study.
Twenty-one patients visiting the out-patient department with synovitis of MCP joint 2 or 3 were divided into two groups by random stratification. Ten patients received an intra-articular injection with corticosteroids in their MCP joint immediately after stratification. Eleven patients were injected after the second examination and served as negative controls. Hand function was assessed at days 0 and 7 after stratification by a blinded observer. Patients were instructed not to tell the observer the date of the injection.

Method of injection
The MCP joint was injected with a mixture of 0.5 ml of triamcinolone hexacetonide (Lederspan 20 mg/ml; AHP Pharma Hoofddorp, Hoofdorpp, The Netherlands) and 0.5 ml of lidocaine (5 mg/ml, LUMC, Leiden, The Netherlands) using the superolateral approach.

Assessment methods
Sociodemographic data and disease characteristics were obtained from history and medical records.

Assessment of impairment of the hands.
Grip strength and thumb-to-finger pinch strength were measured with the Martin vigorimeter in kilopascals (kPa) [2]. The best of three attempts was recorded. Maximal passive range of motion of the MCP joint was assessed in degrees with a goniometer according to standard orthopaedic measurements [3]. The Ritchie pain score [4] (range 0–3; 0 = no pain, 1 = painful, 2 = pulls faces, 3 = pulls back) and swelling (range 0–1, 0 = no swelling, 1 = swelling) of the joint on palpation were recorded. Disease activity was determined by the patient's assessment of pain, swelling, disease activity and morning stiffness of the MCP joint on a horizontal visual analogue scale (VAS; range 0–100 mm). On the second visit patients were asked if the MCP joint had improved (score = 1), remained stable (0) or worsened (- 1) since the last examination (the transition question).

Hand function assessment.
The use of the hands in the activities of daily life was measured by the Dutch Arthritis Impact Measurements Scales (AIMS) items for manual dexterity, which included questions about writing, buttoning clothes, tying shoes and opening a jar of food [5]. In the observer-blind treatment study, three of the Jebsen hand function tasks were measured, including turning over five cards, picking up small and large objects and placing them in a container, and stacking four draughts [6]. The Jebsen tasks were carried out with the injected hand and were recorded as time in seconds for each item, with a maximal score of 90 s.

Statistical analysis
MCP joints 2 and 3 were analysed together. All statistical analyses were performed using the SPSS statistical program, with P < 0.05 as the level of statistical significance.

The hypothesis that the mean was the same at the two time points was tested by the paired Student's t-test. The average intraclass correlation was calculated for the parameters in the reliability study. An unpaired t-test was used to determine differences between the parameters of non-treated and treated patients in the observer-blind treatment study. For the non-normally distributed parameters (AIMS questions, Ritchie pain score and swelling), the Mann–Whitney test was used to determine differences between the parameters of non-treated and treated patients in the observer-blind treatment study.

To evaluate the size of the effects as distinct from their statistical significance, the magnitude of changes was described in terms of effect size (ES) [7], where ES = (pretreatment mean – post-treatment mean)/pretreatment standard deviation.


    Results
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
The characteristics of the 74 patients in this study are shown in Table 1Go.


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TABLE 1. Demographic data and disease characteristics of the patient groups

 
Reliability of measurements
In the reliability study the hand function of 25 RA patients was measured on two occasions within 2 weeks of each other. The first and second measurements of the parameters had an intraclass correlation between 0.45 and 0.97. A significant difference between the two time-points was observed for the parameters passive flexion, the VAS question about activity and the Ritchie pain score (Table 2Go).


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TABLE 2. Parameters in the reliability and open treatment studies

 

Open treatment study
The hand function of 28 patients was measured before and 4–10 days after local treatment of synovitis of MCP joint 2 or 3 by intra-articular injection of corticosteroids. A significant difference between the first and second measurements was observed for all parameters (Table 2Go).

Randomized observer-blind treatment study
Twenty-one patients were randomized into two groups. Ten patients received a corticosteroid injection directly after the first examination. Eleven patients were injected after the second examination on day 7. The hypothesis that the measurements of day 0 and day 7 remained stable was tested for each parameter in the treated and non-treated patient groups separately. In the non-treated group of patients, the Ritchie pain score and the result of the Jebsen card-turning task appeared to change spontaneously over time. In the group of patients treated with corticosteroids at day 0, a significant difference between the second and the first measurement was observed for flexion of the joint, the VAS item about swelling, the Jebsen card-turning and draught-stacking tasks, the percentage of swollen joints on palpation, the Ritchie pain scores, the transition question and the AIMS question about buttoning clothes (Table 3Go). The effect size exceeded 0.5 for passive joint flexion, all VAS questions, the Ritchie pain score and the AIMS question about buttoning clothes. The non-treated and treated patients differed significantly in passive joint motion, the VAS questions about activity and swelling, the assessment of swelling on palpation, the Ritchie pain score, the transition question and the AIMS question about buttoning clothes (Table 3Go).


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TABLE 3. Parameters in the observer-blind treatment study

 


    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
This study demonstrates that it is feasible to measure the short-term efficacy of local treatment of MCP joints 2 or 3 with reliable and discriminative tests. Such tests are important in the evaluation of the new local therapies that are currently under development.

In the reliability study the patients were scored at an interval of approximately 1 week to minimize the effect of the observer's memory on the reliability of the measurements. During the hospitalization of the patients in the reliability study, the treatment for rheumatoid arthritis was optimized and hand function was trained daily. Therefore, a possible disadvantage of our experimental setting was the possibility that the disease state improved. Despite this, the study shows that most parameters can be measured reliably, including passive extension of the hand, grip strength and pinch strength, the VAS questions about pain, morning stiffness and swelling, the assessment of swelling on palpation, the transition question, and the Dutch AIMS questions. However, an effect of hospitalization is possible for flexion of the MCP joint, the VAS activity item and the Ritchie pain score. In the non-treated group of the observer-blind treatment study, in which patients were not trained daily, flexion of the MCP joint and the VAS activity item remained stable while the Ritchie pain score deteriorated. Therefore, flexion of the MCP joint and the VAS activity were considered reliable, but it seems sensible to judge the changes in the subjective Ritchie pain score carefully.

The reliability of measurements was studied in patients hospitalized in a rheumatology clinic, whereas the treatment studies were performed in patients visiting the out-patient department. The hospitalized patients tended to have more long-standing and destructive disease with worse hand function at first measurement than the patients visiting the out-patient department. Patients in the treatment studies were selected because they had synovitis of MCP joint 2 or 3, whereas this was not an inclusion criterion for patients in the reliability study. This is probably the cause of the poorer scores of the patients in the treatment studies on the visual analogue scales (Table 1Go).

In the treatment studies, it was hypothesized that intra-articular injection of corticosteroids is an effective local treatment for arthritic MCP joints [7]. Since each injection carries with it a small risk of infection, patients in the non-treated group did not receive a placebo injection. Thus, the patients in the randomized observer-blind treatment study were aware of their treatment. This implies that not only the effect of the corticosteroid injection but also the placebo effect was measured. Since the goal of this methodological study was the development of a test that is capable of detecting differences before and after treatment, this shortcoming of the design of the study seems acceptable.

In the open treatment study, 96% of the patients reported a general improvement after treatment. In the observer-blind treatment study, 60% of the patients injected with corticosteroids at day 0 reported a general improvement of the injected MCP joint, compared with 9% in the non-treated group. These differences can be explained partly by the open character of the first treatment study compared with the follow-up treatment study, which had a blinded observer [8]. Therefore, our conclusions are based on the observer-blind treatment study.

In this study, the effect size was calculated in order to compare the different measures of hand function after corticosteroid injection. The effect size depends on both the size of the difference caused by an intervention and the standard deviation of the outcome parameter. Thus the effect size can give useful information even if a small effect is to be expected. In this study, an effect size of >0.5 was considered relevant.

Impairment was studied by measurements of passive joint motion by goniometer, grip strength and pinch strength and by VAS questions, and swelling and Ritchie pain score were evaluated by palpation. In the corticosteroid-treated patients, flexion and the VAS questions about disease activity and the swelling of the joint improved significantly compared with non-treated patients with an effect size of >0.5, indicating that these parameters are discriminative. The assessments of swelling on palpation and the general opinion of the patient (transition question) were also found to be reliable and discriminative. In non-treated patients the Ritchie pain score had a tendency to change spontaneously. However, the fact that the Ritchie pain score differed significantly between treated and non-treated patients in the observer-blind treatment study argues for the inclusion of this parameter when the efficacy of local therapy of an MCP joint is studied. In our study, grip strength remained stable in both non-treated and treated patients while pinch strength had a tendency to improve in treated patients. It is possible that the treatment of one finger makes some difference to finger-to-thumb strength, but not to grip strength. The measurements of passive extension and the VAS items about morning stiffness and pain did not change significantly after treatment. Therefore, these parameters were considered non-discriminative.

The effects of local therapy of the MCP joint on disability was assessed in the Jebsen tasks of stacking draughts, turning cards and picking up objects and in the AIMS questions about writing, buttoning clothes, tying shoes and opening a jar. On the second occasion, the Jebsen card-turning task was performed faster in both the non-treated and the treated group, suggesting a learning effect rather than improvement due to therapy. The tasks of draught-stacking and picking up objects did not improve after treatment with corticosteroid therapy compared with non-treated patients. The Jebsen tasks of turning cards, picking up objects and stacking draughts are therefore not considered to be useful in the detection of improvement in hand function after successful treatment of an arthritic MCP joint. The AIMS questions about writing, tying shoes, buttoning clothes and opening a jar could be measured reliably, but the questions about writing, tying shoes and opening the lid of a jar did not respond to treatment, having an effect size between 0.07 and 0.27. Therefore, these questions were considered non-discriminative. Only with the AIMS question about buttoning clothes was an improvement with respect to disability observed. It has been reported that pinch grip and grip strength are more related to hand function than pain and swelling of individual joints [9]. In our study no clear improvement in these parameters was found. This indicates that treatment of one MCP joint does not have a major effect on hand function, or that changes in disability are difficult to measure.

When new therapies for the MCP joint are evaluated, it is important to have validated outcome measures. Besides, time is saved when irrelevant outcome measures can be omitted. Unreliable or non-sensitive measures include passive extension, grip strength and pinch strength, the VAS questions concerning pain and morning stiffness, the Jebsen tasks of picking up objects, stacking draughts and turning cards, and the AIMS questions about writing, tying shoes and opening a jar. Therefore, these parameters can be omitted when the short-term efficacy of local treatment of an MCP joint is studied.

This study shows that the short-term efficacy of treatment of synovitis of an MCP joint can be evaluated with reliable and discriminative tests such as the measurement of passive flexion with a goniometer, the evaluation of swelling and Ritchie pain score on palpation, the AIMS question about buttoning clothes, and the VAS question about disease activity. These tests can be used in any short-term clinical evaluation of the efficacy of treatment of synovitis of an MCP joint.


    Acknowledgments
 
We would like to thank Arash Khazen for his help in collecting data.


    Notes
 
Correspondence to: T. W. J. Huizinga, Leiden University Medical Centre, Department of Rheumatology, C4-R, PO Box 9600, 2300 RC Leiden, The Netherlands. Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 

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Submitted 8 November 1999; revised version accepted 15 February 2000.



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