Functional antimuscarinic receptor autoantibodies have recently been described in both primary and secondary Sjögren's syndrome (SS) in a mouse bladder contraction assay. Most patients with these antibodies complained of severe lower urinary tract disturbances, which are not a recognized feature of SS. We compared the severity of self-reported urological symptoms, daytime somnolence, and fatigue between a cohort of patients with primary SS and controls with osteoarthritis (OA).
Female patients were recruited from rheumatology outpatient clinics at 2 hospitals. The American Urological Symptom Index (AUA-7), Epworth Sleepiness Scale, and FACIT-F fatigue self-administered instruments were employed. Results were obtained for 76 patients with primary SS and 43 controls (response rates 85% and 67%, respectively). The patient groups were matched for parity, hormone replacement and diuretic therapy, and number of bladder operations and urinary tract infections, although OA patients were slightly older.
AUA-7 urological symptoms were more severe in patients with primary SS compared to OA controls (p = 0.039). Severe urological symptoms were reported by 61% of primary SS patients compared with 40% of OA controls. This difference was predominantly attributable to bladder irritability associated with urgency (p = 0.015) and not nocturia (p = 0.85). Epworth Sleepiness Scale scores were also more severe in primary SS patients compared to OA controls (p = 0.02), independent of nocturia. The FACIT-F fatigue severity scores were not significantly different between patient groups (p = 0.14).
Urological symptoms and daytime somnolence may be previously unrecognized symptoms of primary SS. These symptoms are consistent with functional disturbances of muscarinic receptors, possibly mediated by muscarinic receptor autoantibodies.