The depression items from the SSAGA telephone interview were prepared for ordinal regression and IRT analyses. The former used an ordinal scale of clinical depression (ClinDep) with four levels, the latter analyzed two gateway and seven symptom items (all yes/no): the details of both are presented in Table I. Prevalence rates for lifetime MD were 15% and 20% in males and females, respectively, as detailed in the Supplementary Information Table I supp. For all analyses, we then excluded participants whose onsets of ClinDep occurred before SLE reporting, removing 62% of the participants with subclinical depression (see Table I) or greater. This only left participants with onsets (which represented an increase from zero symptoms) that occurred only during or after SLE reporting.
