DOI: 10.25934/00004330
title: Domains of health important for Rheumatoid Arthritis patients can be assessed separately: Reliability and Responsiveness of the Rheumatoid Arthritis Impact of Disease Score - 7 items (RAID.7i) 

description: The ultimate aim of treatment in Rheumatoid Arthritis (RA) is to consistently increase and maintain the patient’s health-related quality of life.[1]

This aim is strongly supported by effective and persistent control of the disease process, as recommended by the current paradigm of treatment, epitomised by the treat-to-target strategy. [1-3] However, an important proportion of patients who are otherwise in remission still describe a substantial impact of disease,.[4] In fact, Patient Global Assessment (PGA) accounts for 60 to 80% of all RA patients who do not satisfy the European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) Boolean criteria for remission due a single criterion.[5-9]. This condition, PGA >1 with Tender Joint Count (TJC), Swollen Joint Count (SJC) and C-Reactive Protein (CRP) ≤1, has been designated as “PGA-near remission”, and represents as many as 14-38% of all patients with RA at a given moment in time, in different clinical settings.[5-11]

Having reached a status of PGA-near remission, these patients cannot be expected to improve further through reinforcement of immunosuppressive therapy, given that inflammation is already remitted. We suggest that these patients would however need adjunctive interventions designed to diminish impact of disease, beyond disease control. [12]

To provide this support, it is essential that the health professionals in charge of the patient understand the reasons behind that high PGA, and this requires the use of validated instruments that are discriminative enough to support the choice of adjuvant interventions. Several validated tools are available and have been used to assess the impact of RA in different domains. [13, 14] However, most of them are either generic and non-specific for RA, or too complex and time-consuming to be feasible in clinical practice.

Cooperative work developed with patients under the auspices of EULAR lead to the development of Rheumatoid Arthritis Impact of Disease (RAID), which addresses the 7 principal domains of disease impact identified by patients. These include pain, function, fatigue, considered as core domains[15, 16], and also sleep, emotional and physical well-being and coping.[17-19].

Each domain is evaluated using a single 0 to 10 numeric rating scale (NRS) and has a specific weight used to derive a single integrated RAID score. [20, 21] RAID was initially designed for use in clinical trials and proved to be feasible, reliable and sensitive to change, in different sets of patients. [21-24]

However, used as a single composite score, the RAID would not allow the physician to understand the domains driving the high combined score and design an appropriate treatment strategy. We hypothesised that considering the 7 items of RAID separately (RAID.7i), would provide a valuable tool to select the most appropriate adjuvant interventions to reduce the impact and increase the quality in RA patients, beyond control of inflammation.

The RAID as a single score showed good psychometric properties, with NRS performed as well as when longer combinations of questionnaires were used.[21] Despite, moderate to strong correlations were reported between RAID Sleep/ Mos Sleep disturbance and RAID Function/ Health Assessment Questionnaire (HAQ) [21] and responsiveness and reliability for Sleep and Coping was evaluated previously, [25] evaluation of psychometric properties of each RAID NRS, was not systematically evaluated until now.

The aim of this study is to validate each NRS included in RAID, according the OMERACT filter 2.0 [26]