BACKGROUND: To assess the prevalence of self-reported SLE-related symptoms associated with demographic and biochemical data and connective tissue disease (CTD)-related autoantibodies in a large population-based cohort.
METHODS: Participants of the Dutch Lifelines population cohort filled out the Connective Tissue Disease Screening Questionnaire (CSQ), including 11 questions focusing on SLE-related symptoms (SLE-CSQ) based on the American College of Rheumatology classification criteria. CTD autoantibody screen was performed in 25% of participants.
RESULTS: Of 85 295 participants with complete SLE-CSQ data, after excluding patients with SLE and other CTDs (n=126), 41 781 (49.1%) had no positively answered questions and 2210 (2.6% of total) had ≥4 positive answers. Participants with ≥4 answers on the SLE-CSQ were significantly younger, more frequently female, had lower body mass index (BMI) and were more often smokers than those with negative scores. Furthermore, counts of leucocytes, neutrophils and monocytes were significantly higher in these participants, while the levels of haemoglobin and creatinine were lower. CTD autoantibodies were present in 2.2% of participants with SLE-CSQ score of 0, compared with 3.5% with SLE-CSQ score ≥4 (p=0.001). Multivariate analysis showed, after adjusting for age, gender, BMI and smoking, that haemoglobin levels remained significantly lower in participants with SLE-CSQ score ≥4.
CONCLUSIONS: In this large population-based cohort, 2.6% of participants without diagnosed CTD reported ≥4 positive answers on the SLE-CSQ, indicating high suspicion for SLE. These individuals had demographic and haematological characteristics that differed from the remaining population. Potentially, this questionnaire, in combination with autoantibody determination, can be used as a starting point of a screening cascade in order to detect SLE at an early stage.