Attainment of the Patient-acceptable Symptom State in 548 patients with rheumatoid arthritis: Influence of demographic factors

Patient Experienced Symptom State in rheumatoid arthritis: sensitivity to change in disease activity and impact

OBJECTIVES

The Patient Experienced Symptom State (PESS) is a single-question, patient-reported outcome that is validated to assess global disease impact in RA. This study addresses its sensitivity to change, and reliability.

METHODS

Disease activity, disease impact in the seven domains of RA Impact of Disease (RAID) and PESS were assessed in patients with RA from the NOR-DMARD registry, at two visits, 6 months apart. The PESS over the last week was scored at five levels, from 'very bad' to 'very good'. Disease impact and disease activity were compared between patients who improved, maintained or worsened PESS over time, through one-way analysis of variance, with post hoc Bonferroni correction. Correlations between changes in these parameters were assessed through Spearman's correlation coefficient. Sensitivity to change was assessed by standardized response mean (SRM) between the two visits. Reliability was analysed through intraclass correlation coefficient (ICC) between the two visits in patients with stable disease activity and impact.

RESULTS

In 353 patients [76.8% females, mean (s.d.) 9.9 (9.6) years disease duration], improvement in PESS level was associated with substantial improvements in mean impact in all domains as well as disease activity (P <0.02). PESS change was moderately to strongly correlated with RAID domains and disease activity (rho: 0.4-0.7). PESS was responsive to change (SRM: 0.65, 95% CI: 0.54, 0.76), particularly among RAID responders (SRM: 1.79, 95% CI: 1.54, 1.99). PESS was moderately reliable in patients with stable condition (ICC: 0.72, 95% CI: 0.52, 0.83).

CONCLUSION

PESS is valid, feasible, reliable and responsive, representing an opportunity to improve the assessment of disease impact with minimal questionnaire burden.

Fatigue is associated with disease activity in some, but not all, patients living with rheumatoid arthritis: disentangling "between-person" and "within-person" associations

Background

Previous research has shown an unclear and inconsistent association between fatigue and disease activity in patients with rheumatoid arthritis (RA). The aim of this study was to explore differences in “between-person” and “within-person” associations between disease activity parameters and fatigue severity in patients with established RA.

Methods

Baseline and 3-monthly follow-up data up to one-year were used from 531 patients with established RA randomized to stopping (versus continuing) tumor necrosis factor inhibitor treatment enrolled in a large pragmatic trial. Between- and within-patient associations between different indicators of disease activity (C-reactive protein [CRP], erythrocyte sedimentation rate [ESR], swollen and tender joint count [ SJC and TJC], visual analog scale general health [VAS-GH]) and patient-reported fatigue severity (Bristol RA Fatigue Numerical Rating Scale) were disaggregated and estimated using person-mean centering in combination with repeated measures linear mixed modelling.

Results

Overall, different indices of disease activity were weakly to moderately associated with fatigue severity over time (β’s from 0.121 for SJC to 0.352 for VAS-GH, all p’s < 0.0001). Objective markers of inflammation (CRP, ESR and SJC) were associated weakly with fatigue within patients over time (β’s: 0.104–0.142, p’s < 0.0001), but not between patients. The subjective TJC and VAS-GH were significantly associated with fatigue both within and between patients, but with substantially stronger associations at the between-patient level (β’s: 0.217–0.515, p’s < 0.0001). Within-person associations varied widely for individual patients for all components of disease activity.

Conclusion

Associations between fatigue and disease activity vary largely for different patients and the pattern of between-person versus within-person associations appears different for objective versus subjective components of disease activity. The current findings explain the inconsistent results of previous research, illustrates the relevance of statistically distinguishing between different types of association in research on the relation between disease activity and fatigue and additionally suggest a need for a more personalized approach to fatigue in RA patients.

Trial registration Netherlands trial register, Number NTR3112.