Increased severity of lower urinary tract symptoms and daytime somnolence in primary Sjögren's syndrome

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.