Connective tissue diseases in primary biliary cirrhosis: A population-based cohort study

AIM: To establish the frequency and clinical features of connective tissue diseases (CTDs) in a cohort of Chinese patients with primary biliary cirrhosis (PBC). METHODS: Three-hundred and twenty-two Chinese PBC patients were screened for the presence of CTD, and the systemic involvement was assessed. The differences in clinical features and laboratory findings between PBC patients with and without CTD were documented. The diversity of incidence of CTDs in PBC of different countries and areas was discussed. For the comparison of normally distributed data, Student' s t test was used, while non-parametric test (Wilcoxon test) for the non-normally distributed data and 2 x 2 chi(2) or Fisher's exact tests for the ratio. RESULTS: One-hundred and fifty (46.6%) PBC patients had one or more CTDs. The most common CTD was Sjogren's syndrome (SS, 121 cases, 36.2%). There were nine cases of systemic sclerosis (SSc, 2.8%), 12 of systemic lupus erythematosus (SLE, 3.7%), nine of rheumatoid arthritis (RA, 2.8%), and 10 of polymyositis (PM, 3.1%) in this cohort. Compared to patients with PBC only, the PBC + SS patients were more likely to have fever and elevated erythrocyte sedimentation rate (ESR), higher serum immunoglobulin G (IgG) levels and more frequent rheumatoid factor (RF) and interstitial lung disease (ILD) incidences; PBC + SSc patients had higher frequency of ILD; PBC + SLE patients had lower white blood cell (WBC) count, hemoglobin (Hb), platelet count,gamma-glutamyl transpeptidase and immunoglobulin M levels, but higher frequency of renal involvement; PBC + RA patients had lower Hb, higher serum IgG, alkaline phosphatase, faster ESR and a higher ratio of RF positivity; PBC + PM patients had higher WBC count and a tendency towards myocardial involvement. CONCLUSION: Besides the common liver manifestation of PBC, systemic involvement and overlaps with other CTDs are not infrequent in Chinese patients. When overlapping with other CTDs, PBC patients manifested some special clinical and laboratory features which may have effect on the prognosis.