The article you referenced explores the occurrence of axial spondyloarthritis (axSpA) in patients who begin experiencing chronic low back pain after the age of 45, a group that is often less studied compared to younger patients. The researchers aimed to understand the prevalence of axSpA in this age group and compare their characteristics with those who develop the disease earlier in life.
Background
Axial spondyloarthritis is a type of inflammatory arthritis primarily affecting the spine and sacroiliac joints. It often manifests as chronic back pain, stiffness, and limited mobility. Typically, axSpA is diagnosed in younger adults, but this study focuses on those over 45. The goal was to see how common axSpA is among older patients with late-onset chronic back pain and to understand whether these patients differ from younger individuals in terms of clinical symptoms, test results, and response to treatment.
Methods
The study included 116 patients diagnosed with axSpA between 2017 and 2021. It was an observational, cross-sectional study, meaning the researchers collected data from the patients at a single point in time rather than following them over a period. The researchers gathered detailed information on:
• Blood tests (including the HLA-B27 genetic marker, which is often associated with axSpA)
• Imaging studies like X-rays and MRIs of the sacroiliac joints to look for acute or chronic damage
• Ultrasounds of areas where tendons and ligaments attach to bone (enthesis) to check for inflammation
• Clinical symptoms such as the characteristics of their back pain, morning stiffness, response to NSAIDs, and pain levels
• Various functional scores (such as BASDAI and BASFI) that measure disease activity, functional ability, and impact on daily life
Results
The study found that 31% of the patients first experienced low back pain after the age of 45. Among these older patients, several characteristics stood out when compared to patients who developed axSpA earlier in life:
• Gender: Women were more likely to experience late-onset back pain. 51% of the older group were female, compared to 29% in the younger group.
• Psoriasis: There was a higher prevalence of psoriasis (42% vs. 17%) in patients who developed back pain later, suggesting that for many older patients, their spinal problems might be part of psoriatic arthritis rather than traditional axSpA.
• Smoking: A higher proportion of younger patients smoked (57% vs. 38%), though this difference was not statistically significant.
• Response to NSAIDs: Older patients had a lower response rate to NSAIDs (52% vs. 73%), a common treatment for axSpA.
• HLA-B27 positivity: Fewer older patients tested positive for HLA-B27 (32% vs. 54%), which could explain some of the differences in disease characteristics.
• Delayed Diagnosis: Older patients had a shorter delay in diagnosis (40 months compared to 93 months in younger patients). This could be due to the fact that their symptoms were more distinct or that they were more proactive in seeking care.
In terms of disease activity and imaging findings, there were no significant differences between older and younger patients. Both groups had similar levels of inflammation and damage seen on MRIs or X-rays, meaning the disease progresses similarly in both age groups.
Logistic Regression Analysis
The researchers performed a logistic regression to identify which factors were independently associated with late-onset axSpA. They found that:
• Male sex was associated with a lower likelihood of late-onset axSpA (OR 0.2), meaning women were more likely to be in this group.
• Psoriasis was strongly associated with late-onset axSpA (OR 4.8), emphasizing that older patients often had spinal involvement related to psoriatic arthritis.
• Shorter delay to diagnosis was another key factor for older patients.
Conclusion
The study concluded that about 28-31% of patients with axSpA developed their symptoms after the age of 45. These older patients were more likely to be women, to have psoriasis, and to experience a shorter delay in diagnosis. The findings suggest that some patients with late-onset chronic back pain may actually have axial involvement due to psoriatic arthritis rather than traditional axSpA.
Implications
This study highlights the importance of considering axSpA in older patients, especially those with psoriasis, who present with chronic back pain. It also suggests that the disease may look slightly different in older patients, with less of a response to NSAIDs and a lower likelihood of testing positive for HLA-B27. The results encourage physicians to be more vigilant in diagnosing axSpA in this population, as early recognition and treatment can improve long-term outcomes.
In essence, while axSpA is often thought of as a disease of younger adults, this study shows that it can also affect older individuals, particularly in the context of psoriatic arthritis, and underscores the need for tailored approaches to diagnosis and management in this age group.