Use of a screening questionnaire for systemic lupus erythematosus among pregnant women in a Mexican population

OBJECTIVE: To conduct a diagnostic assessment of pregnant women using a screening questionnaire for SLE. MATERIALS AND METHODS: This was an analytical cross-sectional study carried out at the National Institute of Perinatology between 1 November 2019 and 28 February 2020, using a screening questionnaire for SLE. Antinuclear antibody and anti-double stranded DNA antibody tests and a clinical assessment by a rheumatologist were conducted for participants who obtained ≥4 positive responses on the questionnaire. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the screening questionnaire for SLE were calculated. RESULTS: The questionnaire survey was conducted with 540 pregnant patients, 22 of whom (4.1%) had ≥4 positive responses. An antinuclear antibody test was conducted in all aforementioned 22 patients; 17 (77.3%) showed titres of ≥1:80. Of the 22 patients, 19 (86.4%) underwent clinical assessment by a rheumatologist. The patients were classified according to the SLE classification criteria: 7/19 (36.9%) met the revised 1997 American College Rheumatology (ACR) criteria, 8/19 (42.1%) met the Systemic Lupus International Collaborating Clinics criteria and 7/19 (36.9%) met the 2019 ACR/EULAR criteria (sensitivity=0.86, specificity=0.97, PPV=0.77 and NPV=1 for antinuclear antibody titre of ≥1:80; sensitivity=0.88, specificity=0.98, PPV=0.37 and NPV=1 for SLE according to the 2019 ACR/EULAR criteria). CONCLUSIONS: The questionnaire showed high sensitivity and specificity in the diagnosis of SLE. Given its usability and cost:benefit ratio, this strategy should be used for all patients coming in for their first visit to determine who requires antinuclear antibody testing and who needs to be referred to a rheumatologist.