Results showed that these cases had a higher prevalence of AMI than the controls, with 89 of the appendectomies and 47 of the tonsillectomies experiencing an AMI within the follow-up period. When compared with controls, the added risk was calculated as a hazard ratio of 1.33 (95% confidence interval 1.05 1.70) for appendectomy and 1.44 (95% CI 1.04 2.01) for tonsillectomy.
Dr Janszky, the study's first author, emphasises that the absolute numbers of AMI cases in the study are small, with only slightly more than 400 and 200 total cases of AMI in more than 7.5 million and nearly 4 million person-years of follow-up. "As expected from the young age of the population," he says, "the observed moderate increases in relative risk actually corresponded to very small risk increases in absolute terms." The investigators also note that the study population, despite its size, was restricted to childhood exposure, with participants still relatively young at the end of follow-up. "Consequently," they write, "we cannot directly extrapolate our findings to cases of AMI that occur among older men or women, in whom risk is highest."
In explaining the results the authors also implicate some "complex" long-term effect of the immune system, noting that the appendix and tonsils are secondary lymphoid organs whose removal can affect several aspects of immune activity, including decreased production of immunoglobulins. They also note that atherosclerosis, the underlying pathophysiology of AMI, is widely considered to be an inflammatory process.
"In the light of our current knowledge on the complex relatio
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European Society of Cardiology