|Year : 2017 | Volume
| Issue : 2 | Page : 72-75
Rheumatoid arthritis disease activity index-5: Utility in busy clinical settings
Harpreet Singh1, Vikram Singh Tanwar2, Gagandeep Sukhija1, Rekha Mathur1, Parminder Kaur1
1 Department of Medicine, PGIMS, Rohtak, Haryana, India
2 Department of Medicine, SHKM Government Medical College, Nalhar, Haryana, India
|Date of Web Publication||27-Jan-2017|
Vikram Singh Tanwar
Department of Medicine, SHKM Government Medical College, Nalhar - 122 107, Haryana
Source of Support: None, Conflict of Interest: None
Objective: To assess disease activity using Rheumatoid Arthritis Disease Activity Index-5 (RADAI-5) in patients with rheumatoid arthritis (RA) and its correlation with Disease Activity Score using 28 joint count (DAS28) and Clinical Disease Activity Index (CDAI).
Methods: One hundred patients with active RA (as per ACR 1987 criteria) were assessed for disease activity using DAS28, CDAI, and RADAI-5. Spearman's correlation coefficient (ρ) and Cronbach's alpha were measured to assess the correlation between different disease activity scores and internal consistency, respectively.
Results: In the study population, 81 patients were women and 19 patients were men. Mean age of the patients was 44.4 (±11.8) years. The median scores (interquartile range) for DAS28, CDAI, and RADAI-5 were 5.6 (2.0), 26.5 (22.0), and 5.8 (3.2), respectively. RADAI-5 was found to be significantly correlated with DAS28 and CDAI (allP < 0.001). Cronbach's alpha was highest for the RADAI-5.
Conclusion: RADAI-5 had a positive correlation to DAS28 and CDAI for the assessment of disease activity, and it may be a good alternative to DAS28 and CDAI in busy outdoor settings.
Keywords: Clinical Disease Activity Index, Disease Activity Score, disease activity
|How to cite this article:|
Singh H, Tanwar VS, Sukhija G, Mathur R, Kaur P. Rheumatoid arthritis disease activity index-5: Utility in busy clinical settings. Indian J Rheumatol 2017;12:72-5
| Introduction|| |
Rheumatoid arthritis (RA) is a chronic multisystem inflammatory disease of unknown etiology characterized by symmetric peripheral polyarthritis, resulting in pain and poor quality of life. As soon as a diagnosis of RA is confirmed, prompt initiation of aggressive therapy is recommended to achieve remission or low disease activity state (LDAS). Therapy for RA is titrated according to level of disease activity which is measured by various disease activity assessment scales. These scales guide physicians to make decisions regarding when to use, add, increase, or decrease the dose or even stop medications for RA.
The commonly used assessment tools for disease activity in RA are Disease Activity Score using 28 joint count (DAS28), Simplified Disease Activity Index, and Clinical Disease Activity Index (CDAI). These are mainly physician dependent, not patient-friendly (for self-assessment of disease), and more time-consuming (as all of these need joint counts) and hence, may not be suitable for use in busy clinics to assess disease activity rapidly. RA Disease Activity Index-5 (RADAI-5) is a newly developed tool which is physician as well as patient friendly and can be completed within a minute. To our knowledge, there is no published Indian experience available with RADAI-5 till date. Our objective in this prospective observational study was to assess the disease activity using RADAI-5 and to find its correlation with well-known disease assessment tools (DAS28 and CDAI).
| Methods|| |
Patients and data collection
The study was conducted at rheumatology outpatient clinic, PGIMS, Rohtak, Haryana. One hundred patients with RA, classified as per the ACR 1987 revised criteria, were enrolled in the study prospectively from July 2013 to April 2014. Those patients who were suffering from severe anemia, hypothyroidism, and renal, cardiac, liver or pulmonary disease were excluded from the study group. All subjects were assessed for DAS28 using erythrocyte sedimentation rate (ESR) and CDAI. The 28 joint counts used in the DAS28 ESR and CDAI included shoulders, elbows, wrists, metacarpophalangeal joints, proximal interphalangeal joints, knees but excluded the joints of the feet. All patients were also asked to complete the RADAI-5 questionnaire  simultaneously and to score from each question from 0 (best) to 10 (worst). Total RADAI-5 score was calculated as a mean of nonmissing items which ranges from 0 to 10.
Data collected were statistically analyzed using Statistical Package for Social Sciences (SPSS, Chicago, IL, USA), version 20. Correlations between indices were made by computing Spearman's correlation coefficients (ρ) which range from −1 to +1; All patients were distributed into four groups as per quantification of disease severity assessed by each indices [Table 1]. Disease severity categories defined for RADAI-5 (as per score) were remission (0.0–1.4), low activity (1.6–3.0), moderate activity (3.2–5.4), high activity (5.6–10.0). To assess the reliability of these three scores, Cronbach's alpha was measured.
|Table 1: Reference values of disease activity scores as per disease severity|
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The study was approved by the ethics committee of the institute. Informed written consent was obtained from all patients prior to their enrollment in this study.
| Results|| |
In the study participants, 81 (81%) were women and 19 (19%) were men, with female to male ratio of 4.3:1. Mean age of study population was 44.4 ± 11.8 years and median duration of disease was 48 months. 76 (76%) patients were found positive for rheumatoid factor.
The median values with interquartile ranges of various core set measures and disease activity indices (DAS28, CDAI, and RADAI-5) are shown in [Table 2].
|Table 2: Median values along with interquartile ranges of various parameters|
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The median values of all three indices (DAS28, CDAI, and RADAI-5) indicated high disease activity [Table 2]. When these patients were grouped into four categories as per disease activity (remission, mild, moderate, high) by assessing all three individual scales, the majority of the patients were found to be having moderate to high disease activity (maximum number of subjects in Group 4, i.e., high disease activity group, followed by Group 3, i.e., moderate disease activity group) [Table 3].
|Table 3: Numbers of subjects as per disease severity based on different indices|
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RADAI-5 was found to be correlated significantly with the DAS28 (ρ = 0.862, P < 0.001) and CDAI (ρ = 0.856, P < 0.001) as shown in [Table 4]. All core data set measures were found to be positively correlated to the RADAI-5 (Spearman's ρ = 0.746, P < 0.001 for TJC; Spearman's ρ = 0.512, P < 0.001 for SJC; Spearman's ρ = 0.928, P < 0.001 for PGA; Spearman's ρ = 0.925, P < 0.001 for EGA) [Table 4].
|Table 4: Correlation of rheumatoid arthritis disease activity index‑5 with various disease activity parameters|
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Internal consistency for all scales was performed by calculating Cronbach's alpha. Value of Cronbach's alpha for RADAI-5, DAS28, and CDAI was 0.966, 0.633, and 0.754, respectively.
| Discussion|| |
For the measurement of disease activity in RA, many assessment tools have been developed. These are largely based on patient clinical symptoms, laboratory values, and physician assessment. In the developed countries, the use of objective disease activity measures is also commonly employed in the clinical setting for the care of individual patients. However, in India, there is a lack of awareness about the objective assessment of disease activity scales in RA among general practitioners. Further, paucity of time in busy clinical settings may make clinician more reluctant to agree upon the routine use of an objective disease measure (based on either patient reported or physician measured outcomes). However, due to high variability of presentation and course of RA as well as the reflection of different disease characteristics, no single measure can reliably capture disease activity in all patients.
The DAS28 has been extensively validated and is increasingly used in RA clinical trials and to monitor patients who have RA. However, not surprisingly, some limitations have emerged, for example, lower specificity of DAS28 at remission or LDAS, need for more time to perform joint counts, complicated mathematical calculation of the composite score and the requirement, and ESR or C-reactive protein (CRP) on the day of examination. The result of these tests may not be immediately available to the physician during the patient encounter. DAS28 formula weighs tender joints more heavily than swollen joints, whereas physicians tend to give more importance to swollen joints when making treatment decisions. In addition, ESR has been shown to contribute 15% information in DAS28 which may result in underestimation of remission in high ESR state. Conversely, in low ESR state, it is possible to be in remission despite having a large numbers of swollen joints.
ESR can be influenced by confounding factors such as age, sex, fibrinogen levels, hypergammaglobulinemia, and anemia that can affect the DAS28 ESR value. ESR generally reflects disease activity of the past few weeks and therefore is less sensitive to short-term changes in disease activity. DAS28 CRP was found to be highly correlated with DAS28 ESR in a study done by Das et al. However, DAS28 CRP overestimated high and low disease activity in their study. It has been found that DAS28 overestimates the remission in comparison to other measures. Disagreement was more on the laboratory parameters such as ESR and CRP. It was also found that persisting active inflammation in substantial number of patients despite being categorized into remission by DAS28 (ESR or CRP). CDAI is a good instrument, but there could still be some real and perceived hurdles in its routine use (e.g., needs joint counts).
In a previous study patient reported that physical functions are the most significant predictors of work disability and premature mortality, somewhat greater than joint count measures, and far more significant than the laboratory and radiographic data. This study also concluded that an index of only self-reported measures (physical function, pain, and global estimate of status) may be more efficacious than DAS28 or CDAI which include joint counts. RADAI-5 is a self-administered tool which comprises only five patient-reported measures, thus supporting the suggestion of Pincus et al. The RADAI-5 does not require any physician's intervention, laboratory parameter, biochemical parameter, or radiological investigation for assessment of disease activity. This is the main essence of the RADAI-5 which makes it a suitable or appropriate tool in hospital-based care as well as home-based care settings. Further, the variables used in RADAI-5 are easily available at a point of care in the clinical setting assessed by patient himself, which in turn can produce more consistency in timing and completeness of disease measurement.
Another study found a significant correlation (Spearman's correlation coefficient ranging from 0.64 to 0.74, P < 0.001) when RADAI-5 was compared with DAS28 and CDAI. In another study done by Leeb et al., RADAI-5 was found to be correlated significantly with the complex indices (DAS28 and CDAI). In our study, we also observed a highly significant correlation between RADAI-5 and DAS28 and CDAI (ρ =0.862, 0.856, respectively, all P < 0.001) [Table 4]. Thus, our results were consistent with those of earlier studies [Table 5] and supported the validity of RADAI-5.
|Table 5: Comparative evaluation of studies on rheumatoid arthritis disease activity index‑5|
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RADAI-5 was found to be significantly correlated with core data set measures [all P < 0.001, [Table 4]. In a previous study  RADAI-5 significantly correlated with TJC, SJC, and EGA with Spearman's rho of 0.747, 0.598, and 0.603, respectively, P < 0.001 for all.
Internal consistency (i.e., Cronbach's α) was calculated to measure the reliability of these three indices. The Cronbach's α value for RADAI-5, CDAI, and DAS28 was 0.966, 0.754, and 0.633, respectively, that showed reliability of RADAI-5 was significantly higher than of the other tools (e.g., DAS28 and CDAI). Cronbach's alpha in the aforementioned study was highest for the RADAI-5 (0.917) and lowest for the DAS28 (0.553). Another study also showed that Cronbach's α was highest for the RADAI-5 (0.913) and lowest for DAS28 (0.343). Yet, another study by the same author showed that Cronbach's α for the RADAI-5, DAS28, and CDAI was 0.906, 0.165, and 0.210, respectively. Thus, we can infer that RADAI-5 is a reliable tool that assesses disease activity with similar efficacy to established disease activity scores such as DAS28 and CDAI.
The limitations of our study were that the study was performed in a single center within a relatively small region. In addition, fibromyalgia that coexists in 15%–20% of RA patients could have exerted an influence on RADAI-5. There is also need to assess the sensitivity of RADAI-5 to change over time corresponding to changes in disease activity.
The results of our study showed RADAI-5 to be a reasonable tool to assess disease activity in RA (in spite of not including joint counts) and had a strong positive correlation to DAS28 and CDAI. RADAI-5 had high reliability in terms of internal consistency. In the Indian context, where a large percentage of patients may not have available values of ESR or CRP due to multitude of reasons, RADAI-5 could be a good alternative to DAS28 and CDAI in busy clinics.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]