A Systematic Review of Clinical Trial Designs and Outcome Measures in Sjögren Disease Randomized Controlled Trials

To systematically review all existing Sjögren disease (SjD)-related instruments reported in clinical trials for SjD.

We systematically searched Medline (PubMed) and EMBASE between January 2002 and March 2023 to identify all randomized controlled trials (RCTs) using both a manual approach and artificial intelligence software (Bibliography BOT). We extracted all the instruments used as primary or secondary outcomes and assessed whether the study succeeded in improving the outcome. We also classified the instruments according to the recently defined preliminary outcome domains.

Among 5420 references, 60 RCTs were included, focusing either on overall disease manifestations (53%) or on a single organ/symptom (eg, dry eyes [17%], xerostomia [15%], fatigue [12%], or pulmonary function [3%]). Primary outcomes included measures of oral or ocular dryness, patient-reported outcomes (PROs), systemic activity, and other outcomes. Common instruments used were European Alliance of Associations for Rheumatology (EULAR) Sjögren Syndrome Disease Activity Index (ESSDAI), EULAR Sjögren Syndrome Patient-Reported Index, Schirmer-I test for unstimulated salivary flow, and IgG levels. ESSDAI was a primary outcome in 11 studies, with 45% of studies reaching significance, whereas none of the 16 studies with ESSDAI as a secondary outcome reached significance. PROs were the primary outcome in 34 studies. Glandular function measurements varied, with unstimulated salivary flow as the most commonly measured outcome. Life impact was assessed more frequently as a secondary outcome. Only 2 studies focused on biological activity.

Our review highlighted the heterogeneity of SjD RCTs in both the study designs and outcomes. The use of PROs and composite outcomes has increased in recent years, highlighting a shift from objective dryness measures to more holistic patient-centered outcomes.