Background Beyond the moderate to strong familial aggregation of RA itself, family history of other inflammatory arthritis or lupus and connective tissue diseases (CTD) approximately doubles the risk of developing RA. Being a summary measure of genetic and non-genetic risk factors, it would not be unexpected if family history of these diseases also carried information on RA prognosis, but this has not been studied. A family history of non-RA disease could potentially help distinguish etiological subsets of RA with different disease progression and treatment response.
Objectives To assess if family history of several arthritis-related diseases predict response to TNFi in RA
Methods We performed a cohort study using prospectively recorded data from Swedish nationwide registers. The cohort included all Swedish RA patients starting TNFi as first biologic treatment 2000-2011, with first degree relatives identified through the Multi-Generation Register, and relatives' disease history assessed through the National Patient Register. The association of family history to treatment response (DAS28-based EULAR criteria), treatment switch, and change in disease activity at the evaluation visit at 5 (±3) months was estimated using linear and generalized logistic regression.
Results Among 9249 identified patients, 1014 (11%) had a family history of RA, 201 (2%) of other inflammatory arthritis, 69 (1%) SLE, and 101 (1%) other CTD. There were no significant differences in TNFi response, a lack of association that remained after adjustment for sex, age, birth year, and disease duration (Table), and also when further adjusting for baseline HAQ and CRP.
Conclusions Using a large population-based cohort, we found that despite being predictors of RA itself, family history of RA, inflammatory arthritis, SLE, and other CTD did not predict initial response to TNFi. Although we cannot reject the possibility of weak associations, information on family history of these diseases is not likely to be useful for clinical treatment decisions in this setting.
Disclosure of Interest None declared