People who had their tonsils removed as a child increase their risk of suffering a severe form of arthritis in later life by a third, according to a new study.
Having older brothers or sisters also heightens the risk of ankylosing spondylitis – a type of chronic inflammatory arthritis, say scientists.
They say their findings, published in the journal RMD Open. lend weight to the theory that childhood infections have a role in the development of the condition, which is characterised by inflammation of the spine, joints, and tendon – resulting in pain, stiffness, and fatigue.
While genetic predisposition is the leading cause of the disease, scientists believed that early life factors also play a role.
To explore the theory further, Swedish researchers drew on health and family information contained in national Swedish population registries to compare exposure to various early life risk factors in adults with and without the condition.
Cases had to have had at least one inpatient or outpatient specialist clinic visit with a recorded diagnosis of ankylosing spondylitis between January 2001 and December 2022.
Each case was matched for sex, year of birth, and region of residence with an average of four members of the general public who didn’t have the disease.
Early life risk factors included: mother’s age at delivery, her weight in early pregnancy, and whether she smoked; length of pregnancy; baby’s birthweight; multiple birth; Caesarean section delivery; maternal infections during pregnancy; and season of birth.
Other factors considered were number of siblings; serious childhood infections from birth up to the age of 15; and tonsil or appendix removal before the age of 16.
In all, 6,771 people born from 1973 onwards were diagnosed with ankylosing spondylitis between 2001 and 2022. Of these, 5,612 were born in Sweden and were selected as the cases.
The findings suggest that several factors were associated with a heightened risk of an ankylosing spondylitis diagnosis, among them having just one or more older siblings – a 12 to 15 per cent heightened risk, but not siblings in general.
Study author Dr Matilda Morin, of the Karolinska Institutet (corr), said: “Serious childhood infections were associated with a 13 per cent heightened risk after accounting for potentially influential factors, while tonsil removal before the age of 16 was associated with a 30 per cent heightened risk.
“Multiple birth, as opposed to singleton birth, was associated with a 23 per cent heightened risk, while being born in the summer or autumn months was associated with a significantly lower risk than being born in the winter.”
The researchers then carried out a sibling comparison analysis which indicated an 18 per cent heightened risk for one older sibling compared with none, rising to 34 per cent for two or more older siblings, after adjustment for sex, mother’s age, and year of birth.
Dr Morin said: “The mechanism behind this risk increase cannot be determined from our data but it has been shown that infants with older siblings are more exposed to infections early in life than infants without siblings.”
While the association with serious childhood infections observed in the case–control analysis fell to a four per cent heightened risk, she said the association with tonsil removal rose to a 36 per cent increased risk after adjusting for potentially influential factors.
Dr Morin added: “Having older siblings and a history of tonsillectomy in childhood were independently associated with development of ankylosing spondylitis, even after adjustment for family shared factors in a sibling comparison analysis.
“This strengthens the hypothesis that childhood infections play a role in the aetiology of the condition.”
Produced in association with SWNS Talker
