RT Journal Article
SR Electronic
T1 Association of childhood infections and perinatal factors with ankylosing spondylitis: a Swedish nationwide case–control and sibling study
JF RMD Open
JO RMD Open
FD EULAR
SP e003438
DO 10.1136/rmdopen-2023-003438
VO 9
IS 3
A1 Morin, Matilda
A1 Hellgren, Karin
A1 Lindström, Ulf
A1 Frisell, Thomas
YR 2023
UL http://rmdopen.bmj.com/content/9/3/e003438.abstract
AB Objectives To identify perinatal and early-life risk factors for ankylosing spondylitis (AS), controlling for family-shared confounding with a sibling comparison design.Methods In this nationwide, register-based case–control study, we identified 5612 AS cases from the Swedish National Patient Register, and matched them with 22 042 individuals without inflammatory arthritis from the general population. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of AS in relation to childhood infections and a broad range of perinatal factors including fetal growth. Significant associations were further tested in a sibling comparison analysis, including 3965 patients with AS and their 6070 siblings without a diagnosis of spondyloarthritis.Results We found no statistically significant associations between any studied fetal growth-related factor or other perinatal factors and the risk of developing AS. In contrast, having older siblings (adjusted OR 1.12; 95% CI 1.04 to 1.22 for one vs no older sibling) and history of a childhood tonsillectomy (adjusted OR 1.30; 95% CI 1.13 to 1.49) were associated with AS in the case–control analysis, results that also held in the sibling comparison. Serious childhood infection and multiple birth were significantly associated with AS in the case–control sample, but estimates were attenuated in the sibling comparison.Conclusions Having older siblings and a history of tonsillectomy in childhood were independently associated with development of AS, even after adjustment for family-shared factors in a sibling comparison analysis. This strengthens the hypothesis that childhood infections play a role in the aetiology of AS.Data may be obtained from a third party and are not publicly available.