BACKGROUNDPrimary Sjögren's syndrome (pSS) is one of the autoimmune diseases with high incidence. There were several clinical investigations in Caucasian but seldom in Chinese. The aim of this study was to compare the difference of clinical manifestations, immunological features and prognosis of pSS between Caucasian and Chinese pSS patients.

METHODSFive hundred and seventy-three patients who fulfilled the 2002 international classification (criteria) for pSS from Peking Union Medical College Hospital between 1985 and 2006 were screened retrospectively and compared with other populations.

RESULTS(1) The study consisted of 524 (91%) female and 49 (9%) male patients (female: male = 10.7:1). Mean age at the onset of the disease was (39.0 ± 13.7) years and in 169 (29.5%) patients the disease onset occurred before the age of 30 years. The average duration from disease onset to pSS diagnosis was 48 months (range, 1 - 552 months). It had been shortened during the recent five years. (2) Dry mouth (84.5%) and dry eyes (70.0%) were the most common symptoms, significantly lower than foreign patients (P = 0.000). Two hundred and seventy-two (47.5%) patients presented with rampant caries, 160 (27.9%) with parotidomegaly. The positivity of xerostomia, xerophthalmia and salivary gland biopsy were 91.9%, 94.8% and 90.7%, respectively. (3) Systemic involvement occurred in 91.4% patients. Compared with studies done outside China, higher prevalence of fever 41.0%, myositis 4.9%, pericardial effusion 14.8%, pulmonary involvement 42.3%, renal involvement 33.5%, thyroid involvement 32.7%, pancrease involvement 5.6% (P < 0.01) and lower prevalence of fatigue, lymphadenectasis and Raynaud's phenomenon (P < 0.01) were seen. (4) Risk factors of death include pulmonary artery hypertension, liver damage and interstitial lung disease.

CONCLUSIONSChinese pSS differs significantly from the non-Chinese cases in terms of the age of onset, systemic involvement, autoantibodies and proportional mortality rate. Lung and liver damage were found to be the highest risk factors of the disease prognosis.