Article Text
Abstract
Background The RA-FQ is a new tool to measure RA flares. We have previously provided evidence of construct validity and reliability.1
Objectives We evaluated sensitivity to change of the RA-FQ in clinical trials and observational studies of RA patients with low disease activity.
Methods RA patients in observational studies [CATCH-Canada (n=896) and STPR-France (n=138)], and an RCT (DRESS-Netherlands; n=178) completed 5 items asking whether they were in flare (yes/no), and if so, the severity and duration. We selected patients who said they were not in flare and had a DAS28 <3.2 at thefirst visit (V1). Flare at the next study visit (V2) was defined three ways: 1) patient report (yes/no); 2) patient report-stringent (Boolean: patient report yes AND severity ≥4/10 AND duration >7 days [to increase this reflected increased inflammatory disease activity]; and c) DAS definition often used in studies (DAS28<3.2 at V2 required increase of 1.2; DAS≥3.2 at V2 required increase of 0.6). We compared RA-FQ scores with other PROs and disease activity indicators between flaring and non-flaring patients at V2. Effect size was estimatedusing Cohen's SMD. We hypothesized that at V2, RA-FQ scores would be similar in patients not flaring at both visits, and would be significantly higher in those flaring at V2.
Results The mean difference in RA-FQ scores at V2 ranged from 7.3 (95% CI 1.4, 13.2) in STPR (DAS def) to 19.6 (95% CI 16.7, 22.6) in CATCH (patient report-stringent). The standardized mean difference effect sizes (SMDES) ranged from 0.82–1.95, and were largest for patient report-stringent in 2 studies. SMDE were strong (range 0.84–2.42) for patient global, MD global, HAQ, DAS28, and other clinical indicators except ESR.
The mean difference in RA-FQ scores at V2 ranged from 7.3 (95% CI 1.4, 13.2) in STPR (DAS def) to19.6 (95% CI 16.7, 22.6) in CATCH (patient report-stringent). The standardized mean difference effect sizes (SMDES) ranged from 0.82–1.95, and were largest for patient report-stringent in 2 studies. SMDE were strong (range 0.84–2.42) for patient global, MD global, HAQ, DAS28, and other clinical indicators except ESR.
Conclusions Data from clinical and observational studies support the responsiveness of the RA-FQ in detecting change over time. The robust psychometric properties of the RA-FQ suggest it reliably detects clinically relevant worsening of RA symptoms consistent with increased disease activity and support its use in research and clinical care.
References
Bykerk V et al. RMD Open 2016;2(1):e000225.
References
Disclosure of Interest None declared