Assessment of disease severity in Sjögren's syndrome using semiquantitative parameters on salivary gland scintigraphy

Sjögren's syndrome is a chronic autoimmune disease characterized by lymphocytic infiltration and destruction of exocrine glands. Sjögren's syndrome characteristically involves salivary glands with the presence of xerostomia in the majority (>93%) of patients. The severity of xerostomia can vary from mild to severe and debilitating. Labial histopathology and antinuclear antibodies (ANA) are commonly used in the diagnosis of Sjögren's syndrome but do not correlate well with disease severity. Tests available for objective assessment of disease severity include sialometry and salivary gland scintigraphy (SGS). This study aims to correlate the severity of xerostomia with semiquantitative parameters on SGS.

On the basis of clinical symptoms, the severity of xerostomia was graded into mild, moderate, and severe. Semiquantitative parameters (maximum uptake and excretion fractions) for all salivary glands were calculated on SGS. Spearman's correlation coefficients were calculated to assess correlation with clinical disease severity.

One-hundred thirteen patients (94 females and 19 males) with a median age of 39 years (range: 4-85 years) were included. Of these, 74 had mild, 28 had moderate, while only 11 had severe disease. There was a statistically significant difference between the mean values of maximum uptake and excretion fractions across the three severity groups ( P < 0.05).

Semiquantitative parameters on SGS show a reduction with an increase in the severity of xerostomia. In addition, maximum uptake and excretion fractions correlated well with the severity of xerostomia of Sjögren's syndrome, whereas ANA levels showed no significant correlation with disease severity. SGS can serve as an objective parameter of clinical severity of xerostomia, which is otherwise difficult to determine clinically.