Mouth opening in systemic sclerosis: A longitudinal analysis from the French national cohort study

BackgroundFew studies have evaluated mouth opening (MO) in systemic sclerosis (SSc). None have studied MO trajectories. ObjectiveTo study MO trajectories in SSc. MethodsThis multicentre study included patients enrolled in the French national SSc cohort with at least one MO assessment, described patients based on MO baseline measure, modelled MO trajectories and associated MO measures with SSc prognosis. ResultsWe included 1101 patients. Baseline MO was associated with disease severity. On Kaplan-Meier analysis, MO <30 mm was associated with worse 30-year-survival (p < 0.01) and risk of pulmonary arterial hypertension (p < 0.05). Individual MO trajectories were heterogenous among patients. The best model of MO trajectories according to latent-process mixed modelling showed that 88.8% patients had a stable MO trajectory and clustered patients into three groups that predicted SSc survival (p < 0.05) and interstitial lung disease (ILD) occurrence (p < 0.05). The model highlighted a cluster of 9.5% patients with diffuse cutaneous SSc (dcSSc) (p < 0.05) and high but decreasing MO over 1 year (p < 0.0001) who were at increased risk of poor survival and ILD. ConclusionMO, which is a simple and reliable measure, could be used to predict disease severity and survival in SSc. Although MO remained stable in most SSc patients, dcSSc patients with high but decreasing MO were at risk of poor survival and ILD.