Removing tonsils and adenoids in childhood increases the risk of diseases like asthma, influenza and pneumonia, say scientists who have examined the long-term effects of these common paediatric surgeries for the first time.
The researchers suggest renewed evaluation of alternatives to these surgeries that include removal of tonsils (tonsillectomy) to treat chronic tonsillitis or adenoids (adenoidectomy) to treat recurrent middle ear infections.
The adenoids and tonsils are strategically positioned in the nose and throat respectively to act as a first line of defense, helping to recognise airborne pathogens like bacteria and viruses, and begin the immune response to clear them from the body.
Researchers from University of Melbourne in Australia and University of Copenhagen in Denmark analysed a dataset from Denmark of 1,189,061 children born between 1979 and 1999, covering at least the first 10 years and up to 30 years of their life.
Of the almost 1.2 million children, 17,460 had adenoidectomies, 11,830 tonsillectomy and 31,377 had adenotonsillectomies, where both tonsils and adenoids removed. The children were otherwise healthy.
"We calculated disease risks depending on whether adenoids, tonsils or both were removed in the first 9 years of life because this is when these tissues are most active in the developing immune system," said Sean Byars from University of Melbourne.
The analysis showed that tonsillectomy was associated with an almost tripled relative risk for diseases of the upper respiratory tract.
The absolute risk was also almost doubled for upper respiratory diseases but corresponded to a small increase for COPD, as this is a rarer condition in the community generally.
The team delved deeper into the statistics to reveal how many operations needed to be performed for a disease to occur at a greater rate than normal, known as the number needed to treat or NNT.
The study suggests that shorter-term benefits of these surgeries may not continue up to the age of 30 apart from the reduced risk for tonsillitis (for all surgeries) and sleep disorders (for adenoidectomy).
The researchers note that there will always be a need to remove tonsils and adenoids when those conditions are severe.