313Patient-Reported Outcome Measures in Sjögren’s Syndrome
Patient-reported outcome measures (PROMs) are patient-self-completed question-
naires that assess different disease parameters including functional ability as well as
quality of life. Some questionnaires are generic, hence can be used widely for dif-
ferent diseases, whereas others are specifi c, hence applicable only to specifi c disor-
ders or patient groups. They have been used as an outcome measure tool in different
situations including research trials, standard clinical practice as well as economic
evaluations. The role of PROMs in chronic arthritic conditions has been endorsed
recently by the new trend of the “ patient-centered approach ” [ 18 ]. Its value has been
augmented in some chronic musculoskeletal conditions such as SS and fi bromyal-
gia, which relies mainly on the patients’ symptoms. In SS, PROMs has been used to
assess different aspects of the disease such as disease activity, health-related quality
of life (HRQOL), as well as fatigue.
SS has two main patterns (1) a slowly progressive pattern that affects mainly the
exocrine glands (epithelial regions) and characterized clinically by sicca symptoms
associated with systemic manifestations mainly in the form of fatigue and joint/
musculoskeletal pains and (2) progressive systemic disorder , affecting exocrine
glands, in addition to extraepithelial manifestations as well as serological markers
of autoimmune activation. This highlighted the need for tools to defi ne disease
activity addressing such subjective symptoms as well as systemic and laboratory
features. The EULAR SS Patient-Reported Index (ESSPRI) was developed to assess
the fi rst, and most common, disease pattern, including sicca complaints such as dry-
ness, fatigue, and pain from the patients’ perspective, which are the most important
items from the patients’ point of view. Another index, “EULAR SS Disease Activity
Index (ESSDAI),” was developed to assess global disease activity in relation to the
disease systemic features.
Disease Activity
The ESSPRI was developed as a questionnaire addressing the main primary SS
patients’ symptoms. Considering the patient global assessment as the gold standard
(dependent variable), a multiregression analysis model was implemented to select
the most relevant domains and their weights based on the patients’ perception. This
revealed three main features, namely dryness, pain, and fatigue (both mental and
somatic). The questionnaire adopted the numerical (0–10) scale for each domain to
assess for these features [ 15 , 19 ]. The questionnaire gives a composite total score
defi ned as the mean of the Likert scores (0–10) of dryness, fatigue and pain [ 15 ]
( Appendix 2 ). The EULAR Sjögren’s syndrome (SS) disease activity index
(ESSDAI) is a clinical index that measures disease activity in primary Sjögren’s
syndrome. It includes 12 domains, namely organ systems: cutaneous, respiratory,
renal, articular, muscular, peripheral nervous system (PNS), central nervous system
12 PROMs for Sjögren’s Syndrome