An increased incidence of osteoarthritis in people with atopic diseases such as asthma may support future treatment targets
Introduction
Osteoarthritis is a common condition that makes a person’s joints stiff and painful, particularly in the morning. It is caused by thinning of the cartilage within the joints, which allows the bones to rub against each other. Joint swelling and pain are frequent symptoms. It is the most common of all the different types of arthritis, and typically becomes more common as people get older. Despite the high burden and impact of osteoarthritis, available treatment options are limited and tend to focus on managing symptoms. There are not currently any disease-modifying drugs that halt, slow, or reverse the progression of osteoarthritis.
Mounting evidence suggests that chronic, low-grade inflammation could be involved in the development of osteoarthritis. Previous research has shown that mast cells (a type of allergic cell) are increased in numbers in the joints of people with osteoarthritis, and their activity contributes to the disease developing.1 If this is true, people with atopic or allergic diseases such as asthma or atopic dermatitis (a type of eczema) might be more likely to develop osteoarthritis. This link has not been studied before.
What did the authors hope to find?
The authors wanted to see if the risk of developing osteoarthritis was higher in people with atopic disease. This would be an important finding, as it would support the idea of using treatments that inhibit allergic pathways for the prevention or treatment of osteoarthritis.
Who was studied?
The study looked at over 117,000 adults who had asthma or atopic dermatitis, but without pre-existing osteoarthritis or inflammatory arthritis. As a comparison, the authors also looked at data from over 1 million people who did not have asthma or atopic dermatitis.
How was the study conducted?
This was a retrospective cohort study. This means the authors used existing databases of patient records to look back and find people for each group. There was no specific study treatment given.
The authors used data from insurance claims database and people’s electronic health records. They then looked to see who went on to develop osteoarthritis – and in which joints – and drew comparisons between the groups. As well as comparing people with atopic disease versus those without, they also compared people with asthma compared to people with another lung disease called chronic obstructive pulmonary disease (often shortened to COPD), which is not a disease associated with allergies.
The results were replicated in an independent dataset called STARR. This provided additional information about people’s body mass index (BMI).
What was the main finding?
The main finding was an association between having allergic diseases such as asthma and/or atopic dermatitis and having an increased risk of developing osteoarthritis. More people with asthma or atopic dermatitis had osteoarthritis compared to those without. Overall, the risk of developing osteoarthritis in people with either asthma or atopic dermatitis was about 58% higher in the first analysis, and 42% higher in the STARR dataset. This effect was even stronger in people who had both asthma and atopic dermatitis , with more than twice the risk compared with people without allergic diseases. It was also stronger in people with asthma compared to COPD, with an 83% higher risk.
This study provides support for the observation that mast cells are increased in the joints of people with osteoarthritis, and that these cells may contribute to the development of the disease .
Are these findings new?
Yes, in part. A previous study showed increased rates of osteoarthritis in people with asthma compared to those with COPD, and control patients,2 but the findings were in a small sample, and the way the study was designed meant it was hard to draw conclusions about whether atopic diseases contribute directly to osteoarthritis. The current findings are supported by the previous work, but this new study includes independent data from two much larger groups of people, and included people with atopic dermatitis in addition to asthma. Furthermore, the design of the new study makes it possible to identify people who had an atopic disease diagnosis before the onset of osteoarthritis.
What are the limitations of the study?
One limitation is that this was a retrospective study using insurance claims data. This means there is the potential for residual or unmeasured variables that could affect the results. For example, in some of the databases there was no information available about important variables such as people’s body mass index, BMI, history of trauma to the joints, and level of physical activity.
Another possible limitation is in the way osteoarthritis is diagnosed and recorded in people’s health records. It is possible that use of the wrong codes might have resulted in misclassification; however, the authors note that this risk is the same in both groups.
Finally, the authors did not have access to information on people’s disease severity, or any information about commonly used over-the-counter treatments, such as antihistamines for atopic disease, or non-steroidal anti-inflammatory drugs (NSAIDs) for osteoarthritis.
What do the authors plan on doing with this information?
The current study did not look at ways to modify disease risk for people with osteoarthritis, or the impact of medicines that people might take. But the same research group has looked at this question in another dataset and found that the use of antihistamines was associated with reduced progression of joint damage in osteoarthritis of the knee.3 The authors are hopeful that these new findings might support studies to investigate whether medicines that inhibit mast cells or allergic pathways may help to prevent or treat osteoarthritis.
What does this mean for me?
If you have an atopic disease, it may lead you to develop osteoarthritis. Future research could look into this association, and may develop new treatments that can prevent it.
If you have osteoarthritis, there could be new treatments in the future that might work to modify the disease and prevent damage.
If you have any questions about your disease or its treatment, speak to your healthcare team.
References
- Wang Q, et al. IgE-mediated mast cell activation promotes inflammation and cartilage destruction in osteoarthritis. Elife 2019;8:e39905. doi:10.7554/eLife.39905.
- Koo H-K, et al. Novel association between asthma and osteoarthritis: a nationwide health and nutrition examination survey. BMC Pulm Med 2021;21(1):59. doi:10.1186/s12890-021-01425-6.
- Bihlet AR, et al. OP0230 Antihistamine use and structural progression of knee OA: A post-hoc analysis of two phase III clinical trials. Ann Rheum Dis 2022;81:152.
Date prepared: November 2023
Summary based on research article published on: February 2023
From:Summary from Baker MC, et al. Increased risk of osteoarthritis in patients with atopic disease. Ann Rheum Dis 2023;82(6):866–72. doi:10.1136/ard-2022-223640
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