These cohorts share several key characteristics that make them appropriate for criteria development: Inclusion criteria required that participants have signs and symptoms suggestive of SS, warranting a comprehensive work-up by a multi-disciplinary team of SS clinicians. In addition to symptom-related data, objective tests with respect to oral, ocular, and systemic/serological endpoints had been collected using similar procedures:
Oral tests: labial salivary gland (LSG) biopsy to identify focal lymphocytic sialadenitis (FLS) and focus score (FS)(26 (link)); UWS flow rates.(27 (link), 28 (link))
Ocular tests: OSS using lissamine green and fluorescein, and other ocular tests such as Schirmer test and tear break-up time. For the ocular staining test, the Paris-Sud cohort used the VBS,(29 (link)) while SICCA used the OSS,(30 (link)) and OMRF used both. The Paris-Sud cohort also used fluorescein and collected data on the individual OSS components, so it could be computed subsequently. Thus data from the Paris-Sud and OMRF cohorts could be analyzed to establish a conversion algorithm between both scores as follows: for lower scores, 1–3, the VBS was equal to the OSS, but VBS of 4, 5, or 6 were equivalent to OSS scores of 5, 6, or 7, respectively. For the clinical vignettes, the ocular staining test was expressed as the OSS ranging from 0 to 7 and above. A group of four ophthalmologists from France, the US, and the UK formed an ad-hoc working group that interpreted the analyses performed on the Paris-Sud data (ML and TML) and on the OMRF data (AR). Together, they derived the conversion algorithm between the OSS and the VBS described above. In addition, since the VBS of 4 (previously used in the AECG criteria) was equivalent to an OSS of 5, the group agreed to modify the OSS threshold to 5 in the new criteria set. This threshold has also been shown, as part of subsequent analyses of the SICCA data, to be more specific for diagnostic purposes than the previous score of 3 (data not shown).
Serological assays: including anti-SSA/B(Ro/La), ANA titers, RF, IgG, presence of complement C3 and C4.