Having older siblings, childhood tonsillectomy linked to increased risk for AS in case-control analysis
Factors associated with ankylosing spondylitis (AS) have been identified and include having older siblings and childhood tonsillectomy, according to a study published online Oct. 16 in RMD Open.
Matilda Morin, from the Karolinska Institutet in Stockholm, and colleagues conducted a nationwide, register-based, case-control study involving 5,612 AS cases from the Swedish National Patient Register and 22,042 matched individuals without inflammatory arthritis from the general population. The odds ratios of AS in association with childhood infections and perinatal factors, including fetal growth, were examined. In a sibling comparison analysis, including 3,965 patients with AS and their 6,070 siblings without a diagnosis, significant associations were further explored.
The researchers did not identify any significant associations between any studied fetal growth-related factor or other perinatal factors and the risk for developing AS. In the case-control analysis, having older siblings and a history of childhood tonsillectomy were associated with AS (adjusted odds ratios, 1.12 [for one versus no older sibling] and 1.30, respectively); these results persisted in the sibling analysis. In the case-control analysis, serious childhood infection and multiple birth were significantly associated with AS, but in the sibling analysis, these results were attenuated.
“Despite that the association with hospitalized infection was attenuated in the sibling comparison, our findings strengthen the hypothesis that childhood infections play a role in the etiology of AS,” the authors write.