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Background: Rheumatoid Arthritis (RA) is a chronic, autoimmune rheumatic disease, frequently affecting women. Evidence suggests that a family history of autoimmune diseases (ADs) increases the risk of RA. Overall, family aggregation studies can bring valuable information regarding the genetic background of this autoimmune disease.
Objectives: To determine the frequency and disease-related characteristics of familial autoimmune diseases co-aggregation in patients with rheumatoid arthritis.
Methods: In this cross-sectional study, we registered 160 consecutive patients diagnosed with RA, according to the 2010 ACR/EULAR Classification Criteria, from a Rheumatology Department in Bucharest, between June 2022 and September 2023. The data regarding the presence of ADs among first to third degree relatives, as well as RA features were collected at hospital admissions, using surveys. For the comparative analysis, the cohort was divided into two subgroups: the patients with at least one relative with an AD and the patients without affected family (Group A and Group B, respectively).
Results: The mean(SD) age of the cohort was 54.8 (14.7) years old, female sex being predominant (88.1%). The disease’s duration had a mean of 14.0 (10.9) years. The frequency of familial co-aggregations was 33.8% as follows: 26.3% had first degree relatives with ADs, 10% had second degree relatives and 3.1% had third degree relatives affected. The most common AD diagnosed among relatives was rheumatoid arthritis, followed by autoimmune hypothyroidism. Moreover, the frequency of patients with relatives diagnosed with RA was 10.0% for first degree relatives, 5.6% for second degree relatives and 1.3% for third degree relatives. First degree relatives were most often identified, with a total of 10 pairs of parent-child and 6 pairs of sibling-sibling diagnosed with RA.
The patients from Groups A had more frequent poliautoimmunity, RA seropositivity and were more frequently treated with biological therapy than Group B (Table 1). Moreover, patients with at least one relative with AD were significantly younger at disease onset, mean (SD) of 35.8 (15.1) years old, compared with 43.3 (15.9) years old (p=0.007).
Conclusion: One third of RA patients appear to have a familial aggregation of ADs, with first degree relatives, particularly parent-child relationships, being more significant. Furthermore, patients with familial aggregation are predisposed to develop the disease at a younger age.
REFERENCES: [1] Kuo CF et al; Familial aggregation of rheumatoid arthritis and co-aggregation of autoimmune diseases in affected families: a nationwide population-based study. Rheumatology (Oxford). 2017 Jun 1;56(6):928-933.
Comparison of the two subgroups:
| Characteristics | Group A
| Group B
| p-value |
|---|---|---|---|
| Age mean(SD) years old | 50.9(14.8) | 57.0(13.9) | 0.035 |
| Disease duration mean (SD) years | 15.09(12.1) | 13.5(10.3) | 0.502 |
| Female sex n, % | 51, 94.4% | 90, 84.9% | 0.078 |
| Age at disease onset mean(SD) years old | 35.8(15.1) | 43.3(15.9) | 0.007 |
| Seropositivity n, % | 49, 90.7% | 91, 85.8% | 0.376 |
| Extra-articular manifestation n, % | 19, 35.2% | 25, 23.6% | 0.120 |
| Necessity of biological therapy n, % | 39, 72.2% | 62, 58.5% | 0.089 |
| Poliautoimmunity n, % | 21, 38.9% | 28, 26.4% | 0.106 |
Acknowledgements: NIL.
Disclosure of Interests: None declared.