DISABILITY AND REHABILITATION, 1997; VOL. 19, NO. 1, 13-19

with women in Assessments of disability rheumatoid arthritis in relation to grip force and pain

ULLA NORDENSKIOLD and GUNNAR GRIMBY

Accepted for publication: September 1996

Keywords rheumatoid arthritis, assistive devices, grip force, pain.

Summary

The aim of this study was to assess disability with the Health Assessment Questionnaire (HAQ) and to evaluate the relation- ships between grip force, pain and difficulty in daily activities. Twenty women with rheumatoid arthritis were assessed with measurements of grip force and pain before and after grip test. Both the original HAQ version and an alternative rating model, not taking the use of assistive devices into account, were used. All patients reported pain which significantly increased after grip test and with a significant inverse correlation to grip force. All patients had assistive devices, on average 15 devices (range 1-27). Ninety-one per cent of the patient's devices were in continued use, most frequently in the categories; Eating, Grip and Hygiene. Disability was significantly correlated to pain, grip force and use of assistive devices. When using the alternative ratings of 20 questions in HAQ, 8 of the 20 questions showed significantly ( p = 0.000340339) lower scor- ing, and the number of questions with significant correlations between grip force and disability increasing from 9 ( r = 0.48474, p = 0~039-0~001) to 14 questions ( r = 0.474.74, p = 0.047-0.00 1). Difference between intrinsic disability (without assistive devices) and actual disability (with such assistance) is not reflected in original HAQ. The present study indicates that assessment of actual disability by the alternative rating model is more often correlated to impairment (grip force) than disability assessed by original HAQ and can be considered to give a better assessment of actual disability than the original HAQ model.

Introduction

In estimating the consequences of a disease, assess- ments are often made both on an organic (impairment) and a personal (disability) level' and may include analysis of the relationship between these levels. Disability is one of the most important consequences for the patients with rheumatoid arthritis.' Fries3 considered that disability is

Authors: Ulla Nordenskiold (author for correspondence) and Gunnar Grimby, Department of Rehabilitation Medicine, Sahlgrenska University Hospital, S-413 45 Goteborg, Sweden.

the most essential category of outcome in arthritis, since a goal in the management of patients with rheumatoid arthritis is preservation of function as well as ability to perform daily activities. Burkhardt ef called attention to the fact that clinical trials ought to focus on enhancing existing disability or preventing disability instead of focusing on disease activity. The Health Assessment Questionnaire (HAQ) Disability Index', has been widely used in its self-administered form, and modified It has been translated into several languages6, ' as an outcome index, and is considered to be a useful 'gold standard'.* Patients with rheumatoid arthritis (RA) often use assistive device^,^ or find other ways to perform tasks in everyday life, in order to reduce their disabilities." As the HAQ rates the use of assistive devices similar to 'much difficulty' it is not sensitive to change after such interventions. Thus, it could also be of value to use HAQ with an alternative analysis which does not have the effect of use of assistive devices on the rating model. In the disablement process, Verbrugge and Jette" dis- tinguish between intrinsic disability (without personal assistance or use of assistive device) and actual disability (with such assistance). They stress the scientific im- portance of measuring both levels of disability. This cannot be done with the original HAQ rating model.

Pain and reduced grip force are major symptoms in rheumatoid arthritis.l09 Patients with RA have problems conducting their daily lives because of painful inflamma- tion in joints, muscle weakness and hand deformities, which frequently causes difficulty in gripping objects. The progressive loss of function starts to develop early in the disease.13 Pincus et a1.12 noted that grip strength and poor functional status were among the predictors of increased mortality in RA patients, and Lansbury14 showed several decades ago that grip strength measures disease severity in RA. Thus, both pain and grip force measurements provide information on the status of a disease but it is not clarified in detail to what degree pain and reduced grip force influence the patients' ability to perform personal ADL, the capacity to care for

0963-8288/97 $12-00 0 1997 Taylor & Francis Ltd

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themselves, and instrumental ADL, activities such as household chore^.'^

In the present study, we analyse and compare the consequences of reduced grip force and pain in daily activities of women with rheumatoid arthritis. The intention was to assess disability with the HAQ disability index and also to use an alternative rating model for HAQ, not taking the use of assistive devices into consideration for ratings.

Methods

PATIENTS

Twenty right-handed women participated in the present study. They were recruited from a specific program at Satra rehabilitation centre, Uppsala Uni- versity, where patients stay for a 4-week rehabilitation period. The women were tested during the first 3 days of their stay. The inclusion criteria were; women with rheumatoid arthritis between 25-70 years, in functional classes 2-3 according to the Steinbrocker scale.16 Of the 24 women being diagnosed as having classical or definitive rheumatoid arthritis by the reference clinic, four women could not participate due to other on-going programs. The mean age of the 20 women in the study was 56 years (range 3 M 9 ) and the mean duration of their disease was 14 years (range 5-34). Eighteen of the 20 women had taken part in a patient education program in Joint Protection for Active Living" at Satra re- habilitation centre or at their local hospitals.

HEALTH ASSESSMENT QUESTIONNAIRE (HAQ) DISABILITY INDEX

The HAQ index, a self-administered questionnaire specifically designed for arthritic patients, was first described by Fries',3 and then translated to Swedish and tested6 as utilized in this study. The disability index consists of eight categories of daily activities, each of them including two or three questions (total 20 questions) representing Dressing/Grooming, Arising, Eating, Walking Hygiene, Reach, Grip and Other activities. The score for the original index ranges from 0 to 3, where 0 = without any difficulty, 1 = with some difficulty, 2 = with much difficulty, with the use of assistive devices or other person and 3 = unable to do. The item with the highest score within each category is selected, then the scores are added and divided by 8 in order to calculate the Disability index. The index of 1.3 or less indicates mild disability, 1-4-1.7 moderate disability and 1-8 or more severe disability.'

The HAQ also included a pain score where the intensity of the patient's pain during the past week was assessed. The score was also from 0 to 3. The HAQ took 5-10 minutes6,' for a patient to complete.

In this study, an alternative scoring of the HAQ disability index (8 categories and 20 questions) also has been utilized in order to assess the patient's actual disability" without allowing the use of assistive devices to influence the ratings (Table 1).

ASSISTIVE DEVICES

A self-report checklist of common devices was used.l0 The patients were asked to indicate which devices they had received, which ones they used and did not use, and why. The women also marked on a visual analogue scale (VAS) (&I 00) how much inconvenience they experienced being dependent on assistive devices, with the scale anchored with no trouble at all and maximal possible trouble.

STUDY PROCEDURE

Pain measurement

Pain was assessed using a 100 mm horizontal visual analogue scale (VAS), where 0 = no pain and 100 = maximum pain. The patients were asked to mark on the line the intensity of the pain in the hand they experienced immediately before and after the testing of their grip force in both the right and left hand. Testing was performed between 9 am and 3 pm.

Grip force measurement

Grip force was measured with the electronic in- strument GRIPPIT (Detektor AB)," which measured both the maximum force (peak) and the average force in Newtons over certain periods, such as 10 se~onds . '~ The grip device and an arm support were mounted on a transportable base. The same standardized grip and body positions together with verbal instructions as already described el~ewhere'~ were employed. Two grip handles were used by all the patients in this study. One was the standard roundbow grip, measuring 45 mm in length, 27 mm in width and 125 mm in circumference. The other grip was size, 50, 27 and 125 mm respectively, but had a pointed bow grip profile.

Grip force, both peak and average values (over 10 seconds), were tested with each grip three times with the right hand, followed by three times with the left hand. The highest peak value and the highest average value of

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1 -

the three force measurements was taken as the final value. There was an interval of one minute between each test and between each grip. The total grip force test period was 11 minutes.

STATISTICAL ANALYSES

Standard statistical methods were used to calculate means, median and correlation coefficients ( r ) . The Spearman non-parametric rank test correlation co- efficient was used to assess correlations of pain and HAQ, and grip force and HAQ, respectively. The non- parametric Mann-Whitney U-test was used to analyse the differences between the patient group and the healthy women group. Differences in pain rating between paired observations before and after the grip test and between the original and alternative HAQ ratings were evaluated by the Wilcoxon signed-rank test. The accepted level of significance was p < 0.05.

Results

The patients demonstrated a moderate disability HAQ score with a mean value of 1-61, and a variation from 0.62 to 2.62, using the original rating model, and 1-35 ranging from 0.50 to 2.38 using the alternative rating model (Table 1, Figures 1, 2). The category Hygiene (taking a tub/bath), being the most difficult question, had the majority of scores with ‘unable to do’ (Table 2). ‘Other activities’ (including vacuuming and shopping), Reach (get down objects from above the head) and Grip (opening jars) were also questions with ‘unable to do’ and ‘ much difficulty ’. Thirteen women avoided altogether 41 activities (‘unable to do’ or ‘done by other person’)

Table 1 ADL4isability in the FL4 women ~~

Variables Mean Median (range)

HAQ disability index, original rating 1.61 1.62 (0.62-2.62)

HAQ disability index, alternative 1.35 1.31 (0.5-2.38) #

HAQ 20 questions, original rating 1.25 1.20 (0.3-2.10)

HAQ 20 questions, alternative rating 0.96 0.85 (0.3-1.80) #

Pain during the past week (&3) 1.78 1.58 (0-3)

*see Methods HAQ disability index, **see Methods HAQ alternative rating. # denotes a significant difference (p < 00003); lower difficulty with the alternative HAQ rating compared to the original HAQ rating.

(0-3);

rating (0-3);;

W 3 ) *

(&3)**

0

0 0 20 40 60 80 100

PAIN BEFORE

0 HAQ original rating model - W HAQ alternative rating model

Figure 1 Correlations between pain values from 20 women with rheumatoid arthritis and HAQ, disability index (mean values), with the original ratings r = 0,570 (p < 0.013) and the alternative rating model r = 0.648 (p < 0.005). The alternative ratings demonstrated signifi- cantly (p < 0.0003) lower scores compared to the original ratings.

HAQ

31 u u q-..Q .o

m m\-

- I . I

0 20 40 60 80 100 120 GRIPFORCE AVERAGE N

0 HAQoriginal rating model -B HAQ alternative rating model

Figure 2 Correlation between grip force, (average values over 10 seconds) and HAQ, disability index, with the original ratings r = -0.533 (p < 0.020) and with the alternative rating model r = -0669 (p < 0.003). The mean values from the RA women demonstrated significantly (p < 0.0003) lower scores with the alternative ratings compared to the original ratings.

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Table 2 ratings, p-values for the differences between these two rating models are shown

Distribution of scores in 20 questions, HAQ ordinary ratings and HAQ alternative ratings, not including the use of assistive devices in the

H A P original ratings H A P altemutive ratirig.~

Diff culty Difficulty without with uith with other Unable without with with with other Unable any some much ass. dev. person to do any .some much ass. dev. person to do

20 questions 0 I 2 2 2 3 0 1 2 2 2 3 p-tlulue H A P

Dress yourself Shampoo Stand up chair In/out bed Cut meat A cup to mouth Prepare a meal Walk outdoors Climb 5 steps Wash your body Take a tub/bath On/off the toilet Reach object Pick up clothes Open car door Open jars Turn faucets Shopping In/out a car Vacuuming

6 I 4 10 6 1 I I 1

10 6 0 2 3 1 8 9 2 2 2 0

12 1 1 6 8 2 7 8 1 3 3 2 5 2 2 0 1 1 6 7 4 3 3 1 1 3 0 6 7 1 2 1 3 10 2 6 12 1 3 4 4

1 I 1 6 8 4 0 2 1 10 6 1 4 0 1 7 1 1 2 4 0 0 11 8 1

13 1 0 5 13 I I 0 0 9 9 2

16 0 0 11 9 0 6 0 0 13 5 2 3 1 0 6 1 1 2 2 2 0 I 10 1 1 0 11 3 5 1

11 0 0 8 10 2 0 0 3 0 1 1 6 6 0 0 I 10 3 0 2 1 3 1 1 3 3 2 2 0 8 8

16 0 0 I 1 1 2 0 4 I 3 10 2 0 1 0 6 12 I 5 1 3 3 9 4

1 1 2 1 0 0 0 0 I 0 0 0 0 0 0 0 1 0 2 0 0 1 1 0 0 0 3 0 0 2 I 2 2 0 0 4 1 1 0 1 3

~

~

00253

0.0008

00003 0.0339

~

-

-

- ~

0.002 1

0.0 143 -

- ~

0,0004 -

-

00253

Table 3 women’g

Grip force (Newtons) in the RA women and in healthy

R A n = 20 grip force grip force

Healthy n = 105

Measurements : mean (range) mean (range) p-value

Grip force right hand 61.0 (8-168) 274 (108404) 0.001

Average value for 10 sec 43.1 (5-105) 229 (94-356) 0.001 Grip force left hand 55.0 (8-132) 257 (104400) 0.001

Average value for 10 sec 36.4 (5-73) 213 (92-337) 0,001

peak value

peak value

most frequently the activities bathing, shopping, vacuuming and opening jars.

As seen in Table 2, most ratings (60%) for score 2 in the HAQ, referred to the use of assistive devices. The women had got on average 15 assistive devices (range 1-27). Ninety-one per cent of the devices were used. The majority of the devices was provided in the categories Eating (springy scissors, breadsaw, potato peeler, stovegrip), Grip (enlarged faucet) and Hygiene (raised toilet seat). Four women marked on the VAS-scale that it was not at all inconvenient to be dependent on assistive devices, the median value being 11 (range CL84).

When using the alternative raring model (not including the use of assistive devices in the rating), scale step 0 (‘without any difficulty’) was used for 21 YO of the ratings, scale step 1 (‘with some difficulty’) for 71 YO, and scale step 2 (‘much difficulty’) was still used for 3 % of

the ratings (Table 2). Differences between the distribution of scores using the two scaling models were most markedly found in the categories Eating (cut meat and prepare a meal), Hygiene (get on and off the toilet), Reach (pick up clothes from floor) and Grip (turn faucets). The mean value is high in Eating, using the original rating model which is mainly due to the high use of assistive devices. Thus, when using the alternative ratings, the 16 ratings in prepare a meal, with score 2, due to the use of devices, have reduced to score 1 (9 patients) and to score 0 (1 1 patients) since the devices no longer influence the choice of score.

Eight of the 20 questions demonstrated significantly lower (p < 0.0003-0.0339) scoring with the alternative ratings, as well as between the original disability index and the alternative index (p < 0.0002).

All the patients noticedpain both before and after grip testing but with large variation. The median pain score was 38 (range 3 to 97) before the grip force test period and increased to a median value of 52 (range 8 to 99) after the test, being a significant difference (JI < 0.001).

The patients showed large variations in their grip force (greater in the peak value than in the average value over 10 seconds) (Table 3). They had significantly (p < 0.001) lower grip force both for the peak and the average value over 10 seconds for the right hand (61 N and 43 N respectively) and for the left hand (55 N and 3 6 N respectively) than the control group’g (274 N and 229 N)

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Table 4 Spearman's correlation coefficients (r) ofpain (before the grip test) and HAQ disability index and the eight categories. (The original and an alternative rating model are demonstrated as pain during past week)

HAQ original HAQ alternative model model

Variables r P < r P <

HAQ disability index 0.57 0.013 0.65 0.005 Dressing/ 0.57 0.013 0.56 0.0 15

Arising 0.45 0050 0.52 0.024 Eating 0.17 n s . 0.66 0.004 Walking 0.5 1 0.027 0.65 0.004 Hygiene 0.37 n.s. 0.38 n.s. Reach 0.48 0.037 0.43 n s . Grip 0.40 n s . 0.43 n s . Other activities 0 3 4 n.s. 0.42 n s .

Grooming

Pain in the past week 0.57 0.013

n.s. = non-significant

for the right hand and for the left hand (257 N and 213 N) (Table 3). The mean peak grip force value and mean average value over 10 seconds in the RA patients were only 22%) and 19% respectively of the control values. The average value over 10 seconds, expressed as a percentage of the peak value, showed a significant difference ( p < 0.001) between the patient group (71 YO) and the control group (83 "/O). There were no significant differences between the results in grip force with the two grip handles with different profiles.

CORRELATIONS OF PAIN, GRIP FORCE AND DISABILITY

Significant correlations were shown between pain before and after grip force test and the HAQ disability index ( p < 0.013), and the four categories Dressing/ Grooming, Arising, Walking and Reach (Table 4). When using the alternative rating model significant correlations were found to the index ( p < 0.005) and to the categories Dressing/Grooming. Arising, Eating and Walking ( p < 0.004-0.015). Pain both before and after grip test was significantly correlated ( p < 0 4 4 . 0 5 ) to pain during the past week. There was also a significant correlation ( p < 0.01) between pain (before and after grip test) and grip force (peak and mean value over 10 seconds) (Table 5). As seen in Figure 1, the pain was significantly correlated r = 0.57 ( p < 0.013) to original HAQ disability index and to the alternative rating model r = 0.65 ( p < 0.005). Figure 1 also demonstrated significantly higher scores ( p < 0.0003) in the women with the original ratings, compared to the alternative ratings.

The women also demonstrated a significant correlation ( p < 0.020) between grip force as an average value over

10 s, the HAQ disability index, and the three categories Dressing, Reach and Grip ( p < 0.0094.034) (Table 5). Almost the same correlations for the grip force peak value were shown. When using the alternative rating model the grip force was correlated to the disability index ( p < 0.004) and all categories ( p < 0.002-0.048) except Arising. In the analysis of the relationship between grip force and the scoring of the 20 questions separately the number of significant correlations with the alternative rating model increased from 9 to 14. As seen in Figure 2, the grip force was significantly correlated r = 0.53 ( p < 0.020) to ratings from HAQ disability index and to HAQ using the alternative rating model r = 0.70 ( p < 0.004). The original HAQ scores demonstrated significantly higher ( p < 0.0003) scores in the women compared to the ratings with the alternative model.

Discussion

The present study demonstrates that there will be significantly lower scores of disability in patients with RA if the assessment is made with the alternative self- administered HAQ rating model compared to the original HAQ model. In the alternative rating model the use of assistive devices as such does not influence the ratings whereas the original model gives an increased score with the use of assistive devices. Also when comparing HAQ with the modified Barthel Index, Bakheit et aL20 showed that HAQ overestimates the degree of disability in patients with rheumatoid arthritis.

All women in the study reported pain with a large range of variation, and pain increased significantly after the grip force test. This indicates that pain in RA patients, as in the small joints of the hand and wrist, partly depends on circumstances. Grip force may be limited by pain in patients with rheumatoid arthritis and cannot easily be interpreted only in terms of capacity of muscle force production.

The HAQ disability index mean score had a significant correlation to both grip force, pain and the use of assistive devices in the women in the present study. However, the category Eating, which includes use of a large number of assistive devices, (22% of all the used devices) is neither correlated to grip force nor to pain using the original HAQ ratings, but when using the alter- native rating model, there are significant correlations. Difficulties in the three categories Dressing, Reach and Grip, (original ratings), which include hand activities with less number of devices as dressing including tying shoelaces, buttoning and shampooing the hair, opening car doors and opening jars, were found to have significant correlations to reduction in grip force in the patients

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Table 5 Correlation coefficients between grip force (average value over 10 seconds) and age, pain before and after griptest, HAQ disability index, eight categories and 20 questions with the original and alternative models in women with rheumatoid arthritis

HAQ original H A P alternative model model

Variables r P < r P <

Age Disease duration Pain before grip test Pain after grip test HAQ disability index

Dressing Arising Eating Walking Hygiene Reach Grip Other activities

0.560 0.015 0.120 n.s. 0.638 0,005 0.621 0005 0.533 0.020 0.593 0.009 0162 n s . 0102 n.s. 0.269 n.s. 0.430 n.s. 0.485 0.034 0533 0.020 0364 n s .

HAQ 20 original model

0669 0004 0.635 0.006 0.147 n.s. 0.452 0.048 0469 0.040 0536 0019 0.498 0029 0.709 0.002 0.494 0.031

H A P 20 alternative model

Variables r P < r P <

HAQ disability index 0.618 0,007 0.727 0002 1 Dress yourself 0.551 0.016 0.601 0.009 2 Shampoo 0.742 0.001 0.742 0.001 3 Stand up chair 0.162 n.s. 0,147 n.s. 4 In/out of bed 0.428 n.s. 0,514 0.025 5 Cut meat 0.135 n.s. 0.455 0.047 6 A cup to mouth 0.214 n.s. 0,313 n.s. 7 Prepare a meal 0136 n.s. 0.532 0.021 8 Walk outdoors 0214 n.s. 0.385 n.s. 9 Climb up 5 steps 0.425 n.s. 0,469 0.041

10 Wash your body 0.611 0,008 0.614 0.008 1 1 Take a tub/bath 0.493 0.032 0,494 0.031 I2 On/olT the toilet 0299 n.s. 0.325 n.s. 13 Reach object 0.530 0,021 0.530 0.021 14 Pick up clothes 0268 n.s. 0.087 n.s. 15 Open car doors 0.488 0.033 0.488 0.033 16 Open jars 0670 0004 0716 0002 17 Turn faucets 0.138 n.s. 0.180 n.s. 18 Shopping 0.475 0039 0,475 0.039 19 In/OUt Of Cdr 0.575 0.012 0.575 0.012 20 Vacuuming 0.444 n s . 0.643 0.005

p-value = Spearman's correlation non-parametric test. n.s. = non-significant.

(Table 5) . Ekdahl et a1.6 and Eberhardt et aI.l3 showed, also in accordance with the present results, a correlation between HAQ and reduction in grip strength, indicating the effect of low grip strength on disability in daily activities in these patients. However, when using the alternative rating model, grip force was in the present study correlated to as much as seven of the eight categories compared to three with the original ratings, demonstrating the expected better correlation between grip force and the actual disability.

The exact threshold levels of grip force for limitation of daily activities have been poorly studied. As a first

attempt, differences in the need of grip force between three various activities were noted." The 22 women with RA in that study were able to perform the tasks setting the table and filling glasses, but only 16 of the 22 women were able to vacuumclean. The average grip force of these women was about the same as in the present study, i.e. 22% of the grip force in healthy women. In the present study, 65.%, (13 of 20 women) avoided some daily activities, the median values were two activities with a range of 1-9. Take a tub bath, vacuuming and shopping include gross body movements and also an activity which demands high grip force, as opening jars was among the most difficult activities, reflecting dis- ability mostly in instrumental daily activities.

The aim of providing assistive devices for individuals with rheumatoid arthritis at an early stage of the disease is to maintain or increase the possibility of performing daily activities and to keep their habits and roles in home and in the community. The actual disability of the patients may be reduced even if they are not performing the activities in a normal way. These aspects should be taken into consideration in a complete disability as- sessment. Consequently there is an increasing demand to develop outcome instruments for people with arthritis, which can take into account the degree of difficulty in a large number of activities without assistive devices as well as after interventions with such technology devices. In clinical practice when measuring disability the outcome instrument must approach realistically to the problems experienced by the individual patient.

With patient education and judiciously selected assistive devices, our purpose is to reduce the con- sequences of the disease both on the impairment and on the disability levels. The original HAQ, used over a longer time-period, is demonstrated to reflect changes in the disease process, but the index fails, however, to detect effects of treatment with devices. The results of the present study demonstrate the differences in rating between the original HAQ rating model and an alterna- tive rating model without allowing the use of assistive devices to influence the ratings. Using this model, correlations to impairment (grip force) are also seen for a larger number of questions. The alternative rating model describes the actual disability and can be useful for evaluation of the effect of assistive devices. Thus, this rating model would be of special interest for intervention studies and clinical use for following effects of treatment in daily activities in patients with rheumatoid arthritis.

Acknowledgements

The authors wish to warmly thank Marita Hedberg for her valuable help in data treatment. This work was supported by grants from the

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20 Bakheit A, Harries S, Hull R. Validity of a self-administered version of the Barthel Index in patients with rheumatoid arthritis. Clinical Rehabilitation 1995; 9 : 234237.

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