Comparative evaluation of disease activity measures for adult-onset Still's disease: a multicentre, retrospective, cohort study.

OBJECTIVE

To comparatively evaluate recent adult-onset Still's disease (AOSD) activity measures-Development and Validation of Disease Activity in AOSD (DAVID), Still's Disease Activity Score (SDAS), Still Activity Score (SAS) with Pouchot's Systemic Score (PSS) in an independent multicentre cohort.

METHODS

DAVID and SDAS were modified (m) by omitting global assessments due to availability and to circumvent incorporation bias. Criterion validity was assessed by receiver operating characteristic (ROC) analysis against the treating physician's determination of disease activity (active vs inactive). Responsiveness was evaluated by comparing mean change in scores between remission and active disease, and Cohen's d. Longitudinal sensitivity to change was assessed using linear mixed-effects models with z-standardised scores and marginal R². Primary analysis uses imputed data, with complete-case sensitivity analysis.

RESULTS

The cohort comprised 86 patients with initially active AOSD (64% female; mean age 39.4±15.0 years). In ROC analyses, mSDAS, mDAVID and SAS showed comparable area under the curves (0.69, 0.68 and 0.68, respectively), whereas PSS had a lower AUC (0.60). Responsiveness was greatest for mDAVID (Cohen's d 0.76 (95% CI 0.30 to 1.20)), followed by mSDAS (0.61 (0.13 to 1.1)), SAS (0.46 (-0.01 to 0.90)) and PSS (0.22 (-0.30 to 0.68)). Longitudinal sensitivity to change, quantified by marginal R², was highest for mDAVID (0.65 (95% CI 0.59 to 0.70)), followed by mSDAS (0.61 (0.55 to 0.67)), PSS (0.61 (0.54 to 0.67)) and SAS (0.55 (0.45 to 0.64)). Sensitivity analyses using complete cases yielded similar results.

CONCLUSION

mDAVID and mSDAS demonstrated the most favourable and largely comparable performance profiles across the evaluated metrics, with mDAVID showing greater responsiveness and mSDAS demonstrating a stronger correlation with the articular disease domain.

TRIAL REGISTRATION NUMBER: ISRCTN86135778.