Renal involvement in primary Sjögren's syndrome: A retrospective study of 103 biopsy-proven cases from a single center in China

Aim: To retrospectively investigate the features of renal involvements in patients with primary Sjögren's syndrome (pSS) with biopsy results. Methods: A total of 2096 pSS inpatients at Peking Union Medical College Hospital in China from 2005 to 2015 were identified. Patients with biopsy-proven renal involvement (SS-renal) and matched controls (SS-only) were recruited. The clinical and pathologic features as well as treatments and outcomes were systematically analyzed. Results: One hundred and three pSS nephritis (inpatients had biopsy-proven renal involvement. Tubulointerstitial 53, 51.5%) was the prominent pathologic pattern with glomerulonephritis (GN) present in 50 (48.5%) of the renal lesions. The patterns of GN lesions included membranous nephropathy (37, 35.9%), mesangial proliferative glomerulonephritis (six, 5.8%) or immunoglobulin A nephropathy (three, 2.9%), minimal change disease (four, 3.9%) and focal segmental glomerulosclerosis (three, 2.9%). Compared to SS-only patients, SS-renal patients had fewer dry eyes and positive objective xerostomia (P < 0.05). They presented with a significantly lower incidence of interstitial lung disease (ILD), leukocytopenia and elevated immunoglobulin G levels (P < 0.05). They received a larger initial dosage of corticosteroid and had a higher mortality rate (P < 0.05). Conclusion: This Chinese SS-renal population with biopsy results has diverse pathologic patterns and distinct clinical features. They are characterized with prominent renal-associated and mild SS-associated features. They received more vigorous treatment but had poorer prognosis.