A new study of over 1 million Danes reports increased risks of infection and allergy in a group of over 60,000 children who had tonsils or adenoids removed.

Byars, S. G., Stearns, S. C., & Boomsma, J. J. (2018). Association of long-term risk of respiratory, allergic, and infectious diseases with removal of adenoids and tonsils in childhood. JAMA Otolaryngology–Head & Neck Surgery. https://doi.org/10.1001/jamaoto.2018.0614 (open access)

The authors, all leaders in evolutionary medicine, conclude that “tonsillectomy was associated with a nearly tripled risk of upper respiratory tract diseases, and that adenoidectomy was associated with doubled risk of COPD and upper respiratory tract diseases and nearly doubled risk of conjunctivitis. Large increases in absolute risk for upper respiratory tract diseases also occurred. Smaller elevated risks for a broad range of other diseases translated into detectable increases in absolute disease risks with high prevalence in the population (infectious/parasitic, skin, musculoskeletal,andeye/adnexadiseases).”

An accompanying commentary notes the possible influence of confounding variables, such as a predisposition to infections or smoking in the home or  made infections and therefore surgery more likely, and also caused subsequent health problems. However, the probability that surgical removal of tonsils and adenoids cause later problems is high, and the documented benefits are low. Like many medical treatments, tonsillectomy is implemented when a problem peaks, ensuring that simple regression to the mean will create the illusion the treatment is effective.