Tendon friction rubs in early diffuse systemic sclerosis: prevalence, characteristics and longitudinal changes in a randomized controlled trial

Abstract

To characterize the baseline tendon friction rubs (TFRs) in early dcSSc and to evaluate the association of change in TFR over 6 and 12 months with changes in modified Rodnan skin score (MRSS) and HAQ-Disability Index (HAQ-DI) over 12 and 24 months, respectively. We analysed data from the d-Pen study, a 2-year study in early dcSSc (< or =18 months from first non-Raynaud's symptom). TFR was scored as present/absent at seven anatomical sites at baseline and every 6 months thereafter. Multivariable linear regression models assessed associations between TFR and change in MRSS, and change in the HAQ-DI, over 12 and 24 months, respectively. Covariates included baseline TFR, change in the TFR over 6 and 12 months, age, sex, duration of SSc, MRSS, and tender joint count and swollen joint count (SJC). Forty-nine (37%) of 134 patients had TFR at baseline, 50% had resolution of their TFR, whereas 21% developed new TFRs. Patients with baseline TFRs were likely to be Caucasian (86 vs 58%) and had a higher HAQ-DI score (P = 0.008). In regression analyses, change in TFR (P = 0.04) and baseline MRSS (P = 0.03) predicted change in MRSS over a 12-month period (Model R(2 )= 0.14). For the HAQ-DI model, independent predictors were change in TFR at 6 months (P = 0.008) and baseline SJC (P = 0.04, Model R(2 )= 0.19). Results were similar for 24-month models. We document the presence of TFR very early in the course of dcSSc. Changes in TFR over 6 and 12 months predict changes in MRSS and HAQ-DI over 12 and 24 months, respectively.