CRP and rheumatoid arthritis: 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.