Osteoarthritis risk factor everyone should know – but probably doesn’t

Despite being the most prevalent form of arthritis, there is currently no known cure for osteoarthritis, and treatment options focus primarily on managing symptoms. Recent studies have linked the development of osteoarthritis with the activation of mast cells, a type of white blood cell, and cytokines – inflammatory chemicals responsible for allergic reactions.

However, it remains unclear whether individuals with allergic asthma or eczema may be more susceptible to developing osteoarthritis.

To investigate this, researchers conducted a comprehensive analysis of medical claims submitted to the nationwide US insurance database, Optum CDM, from January 2003 to June 2019, as well as electronic health records from the Stanford Research Repository (STARR) spanning from 2010 to 2020.

The study examined a group of 117,346 individuals with allergic asthma or eczema (average age 52, with 60% women) and a control group of 1,247,196 people without atopic disease (average age 50, with 48% women) from the insurance claims database. The researchers also selected 109,899 individuals with atopic disease matched for age, sex, race/ethnicity, education level, underlying conditions, length of the monitoring period, and outpatient visits and compared them with 109,899 individuals without allergic asthma or eczema.

The findings revealed that those with allergic asthma or eczema had a 58% higher risk of developing osteoarthritis over an average monitoring period of 8 years than those without atopic disease. This translates to an estimated 27 new cases of osteoarthritis for every 100 individuals with atopic disease, compared to 19 new cases for every 100 individuals without the condition if monitored for 10 years each.

Interestingly, the study found that the trend was even more pronounced among the 4325 individuals with both allergic asthma and eczema, who were twice as likely to develop osteoarthritis than those without atopic disease. Furthermore, individuals with allergic asthma alone were 83% more likely to develop osteoarthritis over an 8-year period than those with chronic obstructive pulmonary disease (COPD), a non-allergic lung disease.

To verify their results, the researchers compared the osteoarthritis risk among individuals with and without allergic asthma or eczema using the STARR health records.

The STARR cohort comprised 114,427 participants, with 43,728 individuals having a history of allergic asthma or eczema and 70,699 without atopic disease. This dataset provided additional information on weight in the form of BMI, a significant risk factor for osteoarthritis.

After adjusting for BMI, the study found that the likelihood of developing osteoarthritis was 42% higher among individuals with either allergic asthma or eczema and 19% higher among individuals with both conditions.

While the study provides valuable insights into the association between atopic diseases and osteoarthritis, the researchers acknowledge several limitations, such as their reliance on insurance claims data, which did not include certain factors that may influence the findings, including BMI, previous joint injuries, or physical activity levels.

The weaker observed associations among STARR participants, who had BMI information available, suggest that other factors may play a role, according to the researchers. Additionally, the study did not collect information on the severity of atopic disease or osteoarthritis, as well as the use of common over-the-counter remedies, all of which may have had an impact on the results.

Despite these limitations, the researchers conclude that patients with atopic diseases have a higher risk of developing osteoarthritis compared to the general population. This association is further supported by recent research indicating that mast cells and type II cytokines play crucial roles in the pathogenesis of osteoarthritis, not just in individuals with atopic disease.

The findings suggest that allergic pathways may contribute to the development of osteoarthritis, and that treatments that inhibit mast cells and allergic cytokines may be beneficial in preventing or treating the condition, not just for individuals with atopic disease but also for non-atopic patients.

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