ABSTRACT Rheumatoid arthritis (RA) is a chronic debilitating autoimmune disease modifying anti-rheumatic drugs (DMARD

Joewono Soeroso

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Folia Medica Indonesiana Vol. 42 No. 3 July – September 2006 : 176 - 180 
 176 
VALIDITY AND RELIABILITY OF RADAR QUESTIONNAIRE FOR PATIENTS  
WITH RHEUMATOID ARTHRITIS  
 
Joewono Soeroso 
Sub-Department of Rheumatology, Department of Internal Medicine,  
Airlangga University School of Medicine 
Dr Soetomo Teaching Hospital 
Surabaya, Indonesia 
 
 
ABSTRACT 
 
Rheumatoid arthritis (RA) is a chronic debilitating autoimmune disease modifying anti-rheumatic drugs (DMARDs) 
are needed to modify the progression of RA. Therefore, a practical tool to monitor disease activities of RA is needed. 
The objectives of this study were to determine physician-patient agreement, and patient-patient reliability of RADAR 
questionnaire translated to Bahasa Indonesia. Twenty two patients who fulfilled The ACR Revised Criteria 1987 for 
RA, not illiterate, and understand Bahasa Indonesia were included in this study. To determine the agreement, 
questionnaire A is firstly completed by the physician, on only for questions 6, then compared to question no 6 of 
questionnaire B which is completed by the patient. To determine the reliability, all questions of questionnaire B is 
blindly compared to all questions of questionnaire C. Without knowing by the patients, questionnaire C is completed 2 
hours afterwards. ICCs were used o measure agreement and reliability. The results showed that more than 60% of the 
ICC values of physician-patient agreement were > 0.65 and more than 90% of the ICC values of patient-patient 
reliability were > 0.65. In conclusion, RADAR questionnaire translated to Bahasa Indonesia showed substantial 
validity and reliability. 
  
Keywords: agreement, reliability, RADAR questionnaire, Rheumatoid Arthritis 
 
Correspondence: Joewono Soeroso, Sub-Department of Rheumatology, Department of Internal Medicine,  
Airlangga University School of Medicine, Dr Soetomo Teaching Hospital, Jl Mayjen Mustopo 6-8, Surabaya,  
Phone: 62-31-5501617 
 
 
INTRODUCTION 
 
Rheumatoid arthritis (RA) is a chronic debilitating 
autoimmune disease with a high psycho-socio-economic 
burden (Wolfe et al 1994). High intensity pain and 
progressive destruction of cartilage, bones and joint 
structures in RA may cause disability and premature 
mortality. The prevalence of RA is between 0.5-2.0 % 
(WHO 1992; Lawrence et al 1994). Among 3700 
patient’s visits at the Dr. Soetomo Hospital 
Rheumatology Outpatient Unit, AR ranked second after 
osteoarthritis (Kusmartatmo et al. 1992). Disease 
modifying anti rheumatic drugs (DMARDs) is a group 
of drugs which are able to modify the progression of 
AR and other autoimmune diseases. This includes 
chloroquine, hydroxychlorouqine, methotrexate, 
sulfasalazine, leflunomide, cyclosporine, gold 
compounds etc (Wijnands et al. 1992; Platt et al. 1993). 
In order to improve the health status of AR patients, 
there must be an instrument for disease activity 
monitoring in RA patients receiving DMARDs (Taal et 
al. 1989). The instrument (e.g. a questionnaire) is 
supposed to be practical and concise. This concept is 
preferable for Indonesian patients, since they may have 
lower education attainment. Measuring signs and 
symptoms of AR which mostly consist of subjective 
components such as pain, stiffness, tenderness through 
traditional collecting method may be costly. Whilst the 
use of a questionnaire can be time and cost saving, 
particularly for laboratory tests (Mason et al. 1992). 
However, we have to be sure regarding the validity and 
reliability of a questionnaire applied in the different 
settings (Fuch et al. 1989; Stewart et al. 1990). 
Therefore, we were trying to determine the agreement 
(can a surrogate for validity) and reliability of the Rapid 
Assessment of Disease Activity in Rheumatology 
(RADAR) questionnaire for AR patients translated to 
Bahasa Indonesia. RADAR questionnaire is a short, 
concise, and self assessing which has been validated for 
RA patients at Boston University, USA (Mason et al. 
1992). 
 
 
Validity and Reliability of Radar Questionnaire for Patients with Rheumatoid Arthritis (Joewono Soeroso) 
 177 
MATERIALS AND METHODS 
 
The study which was done between 1 May 1995 up to 
31 December 1995 included 22 RA patients fulfilled 
The 1987 ACR Revised Criteria for classification of 
AR. The location of study was at The Rheumatology 
Out-patient Unit, Dr. Soetomo Hospital, Surabaya, 
Indonesia. The patient must not be illiterate and 
understand Bahasa Indonesia. A physician specialized 
in internal medicine (dr. JS) who has been working at 
The Rheumatology Outpatient Unit for 3 years, 
undertook history taking and physical examination on 
every single RA patient to establish the diagnosis of 
AR. 
 
 
Table 1. 1987 American College of Rheumatology (ACR) revised criteria for the classification of RA (Arnett et al. 
1988) 
 
Criteria Definition 
1. Morning stiffness 
 
2.Arthritis of three or  
   more joint areas 
 
3. Arthritis of hand joints  
4. Symmetric arthritis 
 
 
5. Rheumatoid nodules 
 
6. Serum rheumatoid  
    factor 
7. Radiographic  
    changes 
Morning stiffness in/around the joints, lasting at least 1 hour before maximal 
improvement 
At least three joint areas simultaneously with soft tissue swelling or joint fluid 
observed by a physician; the 14 possible areas are (right or left): PIP, MCP, wrist, 
elbow, knee, ankle, and MTP joints  
At least one area swollen in a wrist MCP, or PIP joint 
Simultaneous involvement of the same joint areas on both sides of the body (bilateral 
involvement of PIP, MCP, or MTP acceptable without perfect symmetry) 
Subcutaneous nodules over bony prominences or extensor surfaces, or in 
juxtaarticular regions, observed by a physician 
Abnormal amount of serum rheumatoid factor by any method for which the result 
has been positive in < 5% of control subjects 
Erosions or unequivocal bony decalcification localized in or most marked adjacent to 
the involved joints (osteoarthritis changes excluded), typical of rheumatoid arthritis 
on posteroanterior hand and wrist radiographs  
 
 
For classification purposes, a patient is said to 
have rheumatoid arthritis if four of seven criteria 
are satisfied. Criteria 1-4 must have been present 
for at least 6 weeks. Patients with two clinical 
diagnoses are not excluded. MCP, 
metacarpophalangeal; MTP, metatarsophalangeal; 
PIP, proximal inter-phalangeal. 
 
The Instrument 
 
To determine the agreement and reliability of the 
RADAR questionnaire for RA patients in Indonesian 
setting, this was firstly translated from the original 
RADAR questionnaire (Figure 1) to Bahasa Indonesia 
by Dr. JS. To assess the language appropriateness, The 
RADAR Bahasa Indonesia (Figure 2) was blindly 
retranslated to English by another physician (Dr. CE). 
The RADAR questionnaire consists of 6 questions. 
Among them, there are 3 quantitative scaled questions 
with 3 anchored 10 cm visual analog scales (VAS) 
where the patients put, such as their response to disease 
activity levels over the previous 6 months, disease 
activity on the day the patient completed the form, and 
arthritic pain on the day the form is completed.  
 
The other questions are in ordinal manners, such as 
duration of morning stiffness, patient’s functional 
capacity according to Steinbrocker Criteria, the 
presence of pain and tenderness in respective joint 
represented joint counts on 9 joints. There are 3 
versions of one page questionnaire, namely 
questionnaire A, questionnaire B and questionnaire C. 
To determine the agreement, questionnaire A is firstly 
completed by the physician, on only for questions 6, 
then compared to question no 6 of questionnaire B 
which is completed by patients. To determine the 
reliability, completed questionnaire B is compared to 
questionnaire C which is blindly completed by the same 
patient 2 hours afterwards, without knowing that she/he 
will complete the second questionnaire (questionnaire 
C). The blinding completion is applied to minimize 
recall bias. The 2 hour interval was chosen to avoid 
changes in signs and symptoms of RA (Figure 3). 
 
 
 
 
 
 
 
 
 
 
 
Figure 3.The protocol of the study. 
Questionnaire A
Questionnaire B
Questionnaire C
physician-patient 
patient-patient
(blinded)
(blinded)
Folia Medica Indonesiana Vol. 42 No. 3 July – September 2006 : 176 - 180 
 178 
 
 
Analysis 
 
To determine the reliability, questions number 1,2,3 (in 
continuous scale) were assessed through ICCs 
(intraclass correlations coefficient) with mixed model-
agreement type available in SPPS version 9.0. While for 
variables with dichotomous and ordinal scales of 
questions no 4,5,6 were assessed through ICCs with 
parallel model-reliability type. The values of agreement 
of 0.0 – 0.20 is considered as slight agreement, 0.20-
0.40 is considered as fair agreement, 0.40-0.60 is 
considered as moderate agreement, 0.60-0.80 is 
considered as substantial agreement, and 0.80-1.0 is 
considered as almost perfect agreement (Sacket et al. 
1991). The 95% level of confidence was used. 
 
 
RESULTS 
 
Patients’ Characteristics 
 
The number of patients fulfilled the 1987 ACR criteria 
for classification of RA were 26. Four patients were 
excluded from the study, since 1 patient did not 
understand the questions of the questionnaire, 1 patient 
did not understand Bahasa Indonesia, and 2 patients did 
not fill the second questionnaire (questionnaire C). The 
patients included in this study were 20 females and 2 
males. The mean of age was 38.14 years (±11.44). The 
mean of education attainment was 9.73 years (± 5.32). 
All 22 patients (100%) presented morning stiffness >1 
hour, arthritis of three or more joint areas, arthritis of 
hand joints, and symmetric arthritis. No patients 
presented rheumatoid nodule. Nine patients (40.9%) 
showed positive serum rheumatoid factor, and 20 
patients (90.9%) showed radiographic specific changes, 
such as osteoporotic bones around the joints, and joint 
erosion (Table 2). The results of agreements and 
consistencies are shown in Table 2 and Table 3. 
 
 
Table 2. Clinical characteristics of RA patients. 
 
 
Criteria (N=22) 
Patient’s 
presentations 
 
% 
Morning stiffness > 1 hour 22 100 
Arthritis of three or more joint 
areas 
22 100 
Arthritis of hand joints 22 100 
Symmetric arthritis 22 100 
Rheumatoid nodule 0 0 
Positive rheumatoid factor 9 40.9 
Radiographic changes 20 90.9 
 
 
 
 
Table 3. The Physician-patient agreement for question 
no 6. 
 
 
Joints 
ICC 
value 
 
95% CI 
 
p-value 
Shoulders    
 Right 0.67 0.38 - 0.85 0.000 
 Left 0.72 0.44 - 0.87 0.000 
Elbows    
 Right  0.67 0.35 – 0.85 0.000 
 Left 0.55 0.18 – 0.78 0.003 
Wrists    
 Right 0.77 0.60 – 0.85 0.000 
 Left 0.76 0.50 - 0.89 0.000 
Hand 
knuckles 
   
 Right 0.72 0.57 – 0.93 0.000 
 Left 0.62 0.28 – 0.82 0.000 
Finger 
knuckles 
   
 Right 0.48 0.11 – 0.74 0.008 
 Left 0.50 0.10 – 0.75 0.009 
Knees    
 Right 0.84 0.67 – 0.93 0.000 
 Left 0.74 0.50 – 0.81 0.000 
Ankles    
 Right 0.48 0.10 – 0.84 0.009 
 Left 0.63 0.31 – 0.83 0.003 
Ball of foot    
 Right 0.73 0.45 – 0.88 0.000 
 Left 0.83 0.64 – 0.92 0.000 
Toe 
knuckles 
   
 Right 0.83 0.64 - 0.95 0.000 
 Left 0.70 0.40 – 0.86 0.000 
 
 
DISCUSSION 
 
RADAR questionnaire is another alternative for 
physician to measures disease activity in RA. This one 
page questionnaire is understandable, only 5 to 10 
minutes to fill up, requires no special instructions and 
self-assessing. The “agreement” between physician and 
patient was quite substantial, showed by around 60% of 
the ICC values was more than 0.65. The percentages of 
physician-patient agreement were lower compared to 
the results of a study done by Mason et al (1992). 
Mason et al. (1992), in the same study using RADAR 
questionnaire, found that 75% of the questions had Ices 
more than 0.65. Lower education attainment of the 
patients (9.73 ± 5.32 years) was probably related the 
lower percentage of physician patient-agreement in this 
study. In this study, the Ices of patient-patient reliability 
was found to be substantial as well. This was showed by 
> 90% of the Ices of all questions were more than 0.65. 
Some clinicians also developed simplified 
questionnaires to assess disease activities in RA. Egger 
et al. (1985). 
Validity and Reliability of Radar Questionnaire for Patients with Rheumatoid Arthritis (Joewono Soeroso) 
 179 
 
 
Table 4. The Patient-patient reliability for all questions 
 
 
Variables 
ICC 
value 
95% CI p-value 
Disease activity  
 during 6 months 
 
0.82 
 
0.62 – 0.92 
 
0.000 
Disease Activity 
today 
0. 88 0.74 – 0.95 0.000 
Tenderness today 0.67 0.35 – 0.85 0.000 
Functional status 0.89 0.67 – 093 0.000 
Shoulders    
 Right 0.81 0.59 – 0.91 0.000 
 Left 0.67 0.37 – 0.85 0.000 
Elbows    
 Right  0.84 0.65 – 0.93 0.000 
 Left 0.74 0.47 – 0.88 0.000 
Wrists    
 Right 0.79 0.56 – 0.90 0.000 
 Left 0.78 0.54 – 0.93 0.000 
Hand knuckles    
 Right 0.92 0.82 – 0.97 0.000 
 Left 0.73 0.45 – 0.88 0.000 
Finger knuckles    
 Right 0.80 0.57 – 0.91 0.000 
 Left 0.86 0.68 – 0.84 0.000 
Knees    
 Right 0.82 0.76 – 0.96 0.000 
 Left 0.78 0.54 – 0.90 0.000 
Ankles    
 Right 0.68 0.68 – 0.85 0.000 
 Left 0.74 0.47 – 0.88 0.000 
Ball of foot    
 Right 0.85 0.6 5– 0.94 0.000 
 Left 0.85 0.67 – 0.93 0.000 
Toe knuckles    
 Right 0.71 0.40 – 0.81 0.000 
 Left 0.76 0.50 – 0.91 0.000 
 
 
proposed a joint count index by which the clinician 
evaluates 36 joints. Fuchs et al (1989), also developed a 
simplified joint index on 28 joints. Proponents of both 
questionnaires are easier to use and provide information 
similar with previous indices used for the evaluation of 
disease activity. Stewart et al (1990), proposed a self-
report particular index that depicts body diagram of 36 
joints that presently tender and inflamed. A separated 
score must then assign weights, ranging from 3 to 95. 
However, their initial testing did not indicate how such 
designations would affect their weighing8. Those 
questionnaires would be good for evaluating disease 
activity in rheumatic diseases. However, those may not 
reduce the cost and time burden, both for the clinicians 
and the patients, since the number of joints to be 
evaluated is quite numerous. The RADAR 
questionnaire tends to evaluate joints which are 
involved most in RA. Therefore, less number of joint is 
examined. 
 
A questionnaire such as the RADAR, when applied 
alone or in conjunction with a functional status 
measure, may also provide the information gathered by 
the clinician in a clinical trial. RADAR can also be 
frequently administered at minimum burden to the 
patient. For example, RADAR does not need to evaluate 
laboratory parameters, which may cost more. The 
RADAR can also be used as a take home questionnaire 
to self-observe the disease activities of RA for specific 
periods. This study showed that Translated RADAR 
questionnaire is able to represents what the patients’ 
feel about the disease suffered. However, there are some 
weakness and limitations committed in this study. The 
interval of filling the questionnaire B and C was only 
about 2 hours. We have some reasons of this problem 
such as if the patients fill up the question more than 2 
hours, the signs and symptoms may have already been 
changed. We believe that the blinded strategy of filling 
the questionnaire C can reduce recall bias. Besides 
showed substantial physician-patient agreement 
(validity) and patient-patient reliability, this translated 
RADAR questionnaire to Bahasa Indonesia is practical, 
concise in gathering disease activity data in patients 
with RA. We hope this translated questionnaire can be 
applied for evaluation and monitoring of disease 
activities particularly among RA patients in Indonesian 
setting. This study did not evaluate the sensitivity to 
change of the questionnaire. Therefore, we would 
integrate translated RADAR questionnaire to Bahasa 
Indonesia in any clinical trial in RA to determine the 
sensitivity to change.  
 
 
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VALIDITY AND RELIABILITY OF RADAR QUESTIONNAIRE FOR PATIENTS WITH RHEUMATOID ARTHRITIS

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VALIDITY AND RELIABILITY OF RADAR QUESTIONNAIRE FOR PATIENTS WITH RHEUMATOID ARTHRITIS

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