[Family history of rheumatic diseases in patients with rheumatoid arthritis: a large scale cross-sectional study].

OBJECTIVE:To determine the associations between the family history of rheumatic diseases and clinical features in patients with rheumatoid arthritis (RA). METHODS:In total, eight hundred and ninety patients with RA were enrolled. The demographic and clinical data were collected, including gender, age, height, body weight, age of disease onset, history of smoking and drinking, family history of rheumatic diseases, clinical and laboratory features, pain and global visual analogue scale (VAS), and multi-dimensional health assessment questionnaire (MDHAQ). Finally, 803 patients were completed the dataset and were included in the study. RESULTS:In this cohort, the male/female ratio was 1:3.5, and the age of onset was (45.09±14.50) years. A total of 123 (15.32%) patients were accompanied with family history of rheumatic diseases, including RA, spondyloarthritis, Sjögren's syndrome, systemic lupus erythematosus and systemic sclerosis. The percentages of first degree, second degree and both first and second degree relatives were 91 (73.98%), 22 (17.89%), and 10 (8.13%) respectively. The most common disease was RA (70.73%), followed by other rheumatic diseases (21.95%), and RA combined with other rheumatic diseases (7.32%). The clinical and laboratory characteristics were compared between the patients with and without family history. The onset-age of the subjects was significantly different between those with and without family history of rheumatic diseases (39.97 ±13.68 vs. 46.01±14.46; P<0.01), which meant that the onset-age in patients with family history was 6.04 years earlier than that in patients without family history. The patients with family history had higher positive rate of rheumatoid factor (RF) compared with those without family history (78.48% vs. 66.67%, P<0.05). By adjusting with gender, body mass index (BMI), smoking and alcohol drinking, anti-cyclic citrullinated peptide (CCP) antibody and RF level, the age at disease onset in the patients with family history was 4.54 years earlier than that in the patients without family history (β=-4.54; 95%CI:-8.70, -0.38; P<0.05). Further hierarchical regression analysis showed that, the age at onset of the RA patients with family history was 10.02 years earlier than that without family history among the smoking patients (β= -10.02; 95%CI:-17.60, -2.43; P=0.01), while the age at onset of the RA patients with family history was 3.27 years earlier than that without family history among the never smoking patients (β=-3.27; 95%CI:-8.37, 1.82; P=0.21). CONCLUSION:The family history of rheumatic diseases is a risk factor for early onset of RA, and may interact with smoking.