Quantitative assessment of disease activity and patient-reported outcomes are recognized as valuable in the management of rheumatoid arthritis (RA). Complexities of assessment of RA include challenges concerning measures themselves, as a gold standard measure for disease status does not exist. This article discusses the hurdles in the implementation of quantitative assessment of RA in usual clinical care and also provides an example to monitor patients with early RA.
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Objective rheumatoid arthritis (RA) disease activity assessment and target to treatment strategy are crucial to improve outcomes for patients with RA, with benefits particularly pronounced for patients with early RA.
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The purpose of RA assessment is to achieve a rapid and continuous remission in all patients with RA and to improve quality of life and long-term outcomes of these patients.
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Hurdles for the implementation of routine clinical assessment are many, and they must be recognized and overcome.
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Inexpensive, easy-to-use electronic devices have been developed to monitor RA disease activity as part of routine clinical care.
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Extensive clinical assessment including laboratory, doctor-performed, and patient self-reported measures should be the right of every patient with RA anywhere in the world.
Introduction
Objective assessment of disease activity is recommended in the current clinical practice guidelines and treatment recommendations for rheumatoid arthritis (RA). This is in contrast to common practice 30 years ago, which was described by Dr Wright as “clinicians may all too easily spend years writing ‘doing well’ in the notes of a patient who has become progressively crippled before their eyes ….”
Last 30 years have provided new insights to RA management. It was recognized that most patients with early RA had a progressive disease with joint damage, disability, and early death. Evidence from variety of clinical studies have shown that disease-modifying antirheumatic drugs (DMARDs) have to be used more early, aggressively, continuously, and often in combinations to improve outcomes. New potent biologic treatments came to market. A treatment target and routine clinical monitoring to reach that target were found to be crucial for better outcomes.
The evidence for the benefits of objective disease activity assessment and target to treatment strategy to improve functional and structural outcomes is particularly pronounced for patients with early RA. Moreover, good treatment response early in the disease predicts improved long-term outcomes. Disease activity at the baseline, and especially after 3 months, is significantly related to disease activity at 1 year. Achieving remission early in the disease provides sustained reduction in radiographic progression. Failure to achieve low disease activity 3 months after the diagnosis of early RA, as assessed by Disease Activity Score based on 28 joint assessment (DAS28), was found to be associated with high direct and indirect costs over the following 4 years.
Ingredients to reach good clinical outcomes of RA exist. However, data from real life settings indicate that most patients with RA have an active disease, especially in countries with low gross domestic product, and many still become work disabled during the first year of the disease. Traditions rather than data influence treatment decisions. Most of the usual clinical rheumatology care is based on the physicians’ impressions rather than quantitative measures.
Challenges of clinical measures of RA disease activity and patient-reported outcomes
No Single Gold Standard
Quantitative clinical monitoring of musculoskeletal conditions and inflammatory joint diseases is challenging compared with the quantitative monitoring of conditions, such as hypertension or hyperlipidemia, for which single measures can be used as an indicator of disease status and change. A single gold standard for patient assessment, which can be used to assess all individual patients in clinical trials, clinical research, and clinical care is not available for any rheumatic disease, and hence, different types of measures are used in assessment of patients with rheumatic diseases. Because no individual measure reflects RA activity in a valid and reliable fashion, composite indices, derived from multiple individual variables, have been developed for RA activity assessment. The commonly used indices for RA activity assessment are summarized in Table 1 , with each index described in greater details elsewhere. Traditional measures to assess RA, such as joint assessment, laboratory tests, imaging, and patient-reported outcomes (PROs) have limitations and provide only a reflection of the underlying inflammatory process.
| Index | Formula | Range | RA Activity State | |||
|---|---|---|---|---|---|---|
| Remission | Low | Moderate | High | |||
| DAS28 a | 0.56 × √(TJC28) + 0.28 × √(SJC28) + 0.70 × ln(ESR) + 0.014×GH | 0–9.4 | <2.6 | 2.6 to ≤3.2 | >3.2 to ≤5.1 | >5.1 |
| SDAI b , c | TJC28 + SJC28 + CRP + MDGL + PTGL | 0.1–86 | ≤3.3 | >3.3 to <11 | >11 to ≤26 | >26 |
| CDAI c | TJC28 + SJC28 + MDGL + PTGL | 0–76 | ≤2.8 | >2.8 to ≤10 | >10 to ≤22 | >22 |
| RAPID3 c | MDHAQ × 3.3 + Pain + PTGL | 0–30 | <3 | 3 to ≤6 | >6 to ≤12 | >12 |
| PASII c | (HAQII × 3.3 + Pain + PTGL)/10 | 0–10 | ≤1 | >1 to 1.9 | >1.9 and ≤5.3 | >5.3 |
| RADAI d | components and calculation e | 0–10 | – | <2.2 | ≥2.2 to ≤4.9 | >4.9 |
a GH rating is scored on a 0 to 100 scale.
c PTGL rating is scored on a 0 to 10 scale.
d No values of remission reported for RADAI.
e RADAI has 5 components: current disease activity with respect to joint tenderness and swelling; arthritis pain; global disease activity in the last 6 months; morning stiffness (scored as 0 = none, 1 = <30 minutes, 2 = 30 minutes to 1 hour, 3 = 1–2 hours, 4 = 2–4 hours, 5 = >4 hours, and 6 = all day); and joint list score (16 joint or joint groups scored from 0 indicating no pain to 3 indicating severe pain). All 5 components are calculated or transformed to a 0 to 10 scale, and sum of all component scores is divided by 5 to get the RADAI score.
Challenges of clinical measures of RA disease activity and patient-reported outcomes
No Single Gold Standard
Quantitative clinical monitoring of musculoskeletal conditions and inflammatory joint diseases is challenging compared with the quantitative monitoring of conditions, such as hypertension or hyperlipidemia, for which single measures can be used as an indicator of disease status and change. A single gold standard for patient assessment, which can be used to assess all individual patients in clinical trials, clinical research, and clinical care is not available for any rheumatic disease, and hence, different types of measures are used in assessment of patients with rheumatic diseases. Because no individual measure reflects RA activity in a valid and reliable fashion, composite indices, derived from multiple individual variables, have been developed for RA activity assessment. The commonly used indices for RA activity assessment are summarized in Table 1 , with each index described in greater details elsewhere. Traditional measures to assess RA, such as joint assessment, laboratory tests, imaging, and patient-reported outcomes (PROs) have limitations and provide only a reflection of the underlying inflammatory process.
| Index | Formula | Range | RA Activity State | |||
|---|---|---|---|---|---|---|
| Remission | Low | Moderate | High | |||
| DAS28 a | 0.56 × √(TJC28) + 0.28 × √(SJC28) + 0.70 × ln(ESR) + 0.014×GH | 0–9.4 | <2.6 | 2.6 to ≤3.2 | >3.2 to ≤5.1 | >5.1 |
| SDAI b , c | TJC28 + SJC28 + CRP + MDGL + PTGL | 0.1–86 | ≤3.3 | >3.3 to <11 | >11 to ≤26 | >26 |
| CDAI c | TJC28 + SJC28 + MDGL + PTGL | 0–76 | ≤2.8 | >2.8 to ≤10 | >10 to ≤22 | >22 |
| RAPID3 c | MDHAQ × 3.3 + Pain + PTGL | 0–30 | <3 | 3 to ≤6 | >6 to ≤12 | >12 |
| PASII c | (HAQII × 3.3 + Pain + PTGL)/10 | 0–10 | ≤1 | >1 to 1.9 | >1.9 and ≤5.3 | >5.3 |
| RADAI d | components and calculation e | 0–10 | – | <2.2 | ≥2.2 to ≤4.9 | >4.9 |
a GH rating is scored on a 0 to 100 scale.
c PTGL rating is scored on a 0 to 10 scale.
d No values of remission reported for RADAI.
e RADAI has 5 components: current disease activity with respect to joint tenderness and swelling; arthritis pain; global disease activity in the last 6 months; morning stiffness (scored as 0 = none, 1 = <30 minutes, 2 = 30 minutes to 1 hour, 3 = 1–2 hours, 4 = 2–4 hours, 5 = >4 hours, and 6 = all day); and joint list score (16 joint or joint groups scored from 0 indicating no pain to 3 indicating severe pain). All 5 components are calculated or transformed to a 0 to 10 scale, and sum of all component scores is divided by 5 to get the RADAI score.
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