Appendicitis during childhood linked to debilitating rheumatic disease, says study
In a study presented at the European League Against Rheumatism Annual Congress (EULAR 2016), is was shown that appendicitis during childhood almost halved the risk of developing Ankylosing Spondylitis (AS) later in life. However, in contrast, admission to hospital with a childhood respiratory tract infection (RTI) increased the risk. These findings suggest the way the immune system responds during childhood, either by influencing the risk of a severe childhood infection, or by being changed by such an infection, may explain how AS develops.
“Appendicitis has previously and repeatedly been shown to decrease the risk of developing ulcerative colitis,2 but up until now had not been investigated for AS,” says Ulf Lindström, lead author from the Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden. “Despite decades of effort to understand its aetiology, the causes of AS remain poorly characterised, so this is a significant development in helping us better understand this debilitating disease.”
Exposure to microbes, both in the form of infection and in the gut flora, has been implicated in several AS-related conditions, such as reactive arthritis and inflammatory bowel disease (IBD). However, up until now, data supporting the role of any specific environmental exposure in the development of AS have been scarce.
“One potential explanation is that inflammatory responses elicited during the course of childhood appendicitis somehow induce long-lasting immunological changes in the colonic mucosa, which in turn protect these individuals from developing AS,” Lindström concludes.
AS is a painful, progressive and disabling form of arthritis caused by chronic inflammation of the joints in the spine. Prevalence of AS varies globally, and is estimated at 23.8 per 10,000 in Europe and 31.9 per 10,000 in North America.4 Although AS is strongly associated with the genotype HLA-B27, not everyone testing positive for the marker goes on to develop the disease.5
Based on 2,643 cases with AS and 11,064 matched controls, childhood appendicitis was shown to reduce the odds for a later diagnosis of AS by 40%; hospitalisation with a RTI increased the odds by 20%. Hospitalisation for urogenital or gastrointestinal tract infections did not predict an AS diagnosis. Similar (and statistically significant) results were obtained when excluding all cases/controls with a diagnosis of IBD up until two years after the first AS-diagnosis of the index case. The trend was stronger for men than women.
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