Children prescribed courses of antibiotics were found to have twice the risk of developing juvenile arthritis than children who did not receive antibiotics, according to the findings of a new study.

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Researchers estimate that around a quarter of antibiotics prescribed to children are unnecessary. The estimate is higher for antibiotics prescribed for acute respiratory infections.

The study, published in Pediatrics, also found that the more antibiotics the children were prescribed, the greater their risk of juvenile arthritis developing.

It is believed that around half of antibiotics courses prescribed to children for acute respiratory infections are unnecessary, giving more significance to the researchers’ findings.

“Our research suggests another possible reason to avoid antibiotic overuse for infections that would otherwise get better on their own,” says lead author Daniel Horton, a postdoctoral research fellow in the Department of Pediatrics at Rutgers Robert Wood Johnson Medical School in New Brunswick, NJ.

Arthritis is typically associated with older adults, but around 294,000 American children under the age of 18 are believed to have arthritis or other rheumatic conditions.

The condition is typically an autoimmune disorder that causes inflammation in the joints leading to pain, stiffness, mobility problems and, in some cases, loss of vision.

Scientists have been able to explain the cause of around a quarter of juvenile arthritis cases through genetics, indicating that environmental factors may contribute to the risk of developing the disease. In particular, recent studies have shed light on a link between childhood antibiotic use, microbiome disturbance and the onset of autoimmune diseases.

According to Dr. Horton, “antibiotics are one of the better-known disruptors of human microbial communities.” Disruption of the microbiota in the intestines is believed to contribute toward the development of inflammatory bowel disease and rheumatoid arthritis in adults.

For the study, the researchers analyzed data obtained from The Health Improvement Network (THIN), a population-representative medical records database from the United Kingdom. They compared the use of antibiotics in children diagnosed with juvenile arthritis and age- and gender-matched control subjects.

Data from around 450,000 children were assessed and of these, 152 were diagnosed with juvenile arthritis. After taking into account the development of other autoimmune conditions and previous cases of infection, the researchers found that antibiotic prescription was associated with an increased risk of juvenile arthritis.

In particular, children who had upper respiratory tract infections treated with antibiotics were at a higher risk of arthritis than children with untreated upper respiratory tract infections. As no link was found between arthritis and antiviral and antifungal drugs, the researchers were able to link the increase in risk specifically to antibiotics.

“This is an extremely important clue about the etiology of this serious and potentially crippling disease,” states senior author Brian Strom. “If confirmed, it also provides a means for preventing it.”

Dr. Horton explains that patients with juvenile arthritis are more susceptible to serious infections than others as their immune system is less able to defend the body against them. He suggests that the study’s findings could be explained by the hypothesis that an abnormal immune system makes children more vulnerable to serious infection even before they are diagnosed with arthritis.

“Under this hypothesis, antibiotics would be a marker for abnormal immunity rather than a direct cause of arthritis,” he explains. “A majority of children get antibiotics, but only about 1 in 1,000 get arthritis. So even if antibiotics do contribute to the development of arthritis, it’s clearly not the only factor.”

As an observational study, the researchers still do not understand the mechanism behind the increase in arthritis risk and, therefore, further research into this area is warranted.

Last year, Medical News Today reported on a mouse study investigating a new targeted treatment for rheumatoid arthritis that showed promise while minimizing side effects.