Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Unaffected First-Degree Relatives of RA Patients Exhibit a High Prevalence of Joint Symptoms That Is Not Explained by the Presence of RA Autoantibodies: Studies in a Predisposed North American Native Population.

Smolik3,  Irene, Tan3,  Qier, Wang3,  Xikui, Hart3,  Donna, Newkirk1,  Marianna, Bernstein3,  Charles N., Robinson3,  David B.

McGill University
University of Manitoba, Winnipeg, MB, Canada
University of Manitoba

Purpose:

We have previously shown that in a North American Native (NAN) population in Central Canada, the prevalence of RA is 2–3 times higher than that seen in most other populations, with a particularly high frequency of familial disease. We have also demonstrated a high prevalence of anti-citrullinated protein antibodies (ACPA), rheumatoid factor (RF), and of RA-like joint symptoms in the first-degree relatives (FDR) of RA probands from this population. We sought to get a better understanding of the relationship between joint symptoms and RA autoantibodies in disease-free NAN individuals who may be at risk for developing future RA.

Methods:

The prevalence of joint symptoms was compared in three distinct groups: 1) FDR of NAN RA patients (n=306), 2) NAN controls (NC, n=330), and 3) Caucasian controls (CC, n=293). The two control groups had no family history of RA or related autoimmune diseases, and NC were from the same geographic areas as FDR. All study subjects completed a questionnaire which included demographic data, health related habits, family health history, and six questions probing into whether they experience pain, swelling, or stiffness of the hands or of other joints. Anti-CCP2 antibodies were tested by ELISA and RF by nephelometry in FDR (n=287), NC (n=198), CC (n=100).

Results:

The mean age of FDR= 35±13, NC= 33±11, CC= 42±13, p<0.0001. The percentage of females was FDR=69%, NC=63%, and CC=63%, p=ns. In all groups, females reported more joint pain, swelling, and stiffness, and overall had an OR=1.6, p<0.01 for having any joint symptom. Compared to both control groups, FDR were more likely to report joint symptoms in the hands: pain (54%, 35%, 18%); swelling (36%, 16%, 7%); stiffness (40%, 23%, 14%); and in other joints: pain (57%, 34%, 32%); swelling (30%, 17%, 11%); stiffness (39%, 24%, 25%) for FDR, NC, CC, respectively; all comparisons p<0.0001. The high prevalence of joint symptoms in FDR was confirmed after matching FDR to NC by age and sex. Compared to CC, NC had more joint symptoms (p<0.01 for all hand joint symptoms). There was a higher prevalence of joint symptoms in FDR living in urban vs. rural locations (79% vs. 60%, P<0.0001). The prevalence of anti-CCP2 was: FDR = 8.3%, NC = 1%, and CC = 1%, p<0.0001, and RF was: FDR = 4.5%, NC = 1%, and CC= 1%, p<0.05. Logistic regression modeling demonstrated that age and FDR status were strong independent predictors of having any joint symptoms (p<0.0001 for both), while gender, RF, and ACPA status were not significant predictors in the model. Similar results were obtained when modeling the individual joint symptoms, although gender was found to be a predictor of hand symptoms.

Conclusion:

RA-like joint symptoms are more common in FDR of NAN RA patients than in either NAN or Caucasian individuals having no family history of RA, a finding that is not explained by the higher prevalence of ACPA and RF in FDR. This finding, combined with the overall higher frequency of joint symptoms seen in NAN compared to Caucasian controls, and in urban compared to rural FDR raises the possibility that pre-clinical joint symptoms based on biological and psychosocial factors may be part of the risk profile for developing future disease in high risk individuals and populations.

To cite this abstract, please use the following information:
Smolik, Irene, Tan, Qier, Wang, Xikui, Hart, Donna, Newkirk, Marianna, Bernstein, Charles N., et al; Unaffected First-Degree Relatives of RA Patients Exhibit a High Prevalence of Joint Symptoms That Is Not Explained by the Presence of RA Autoantibodies: Studies in a Predisposed North American Native Population. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1068
DOI: 10.1002/art.28835

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