Eye inflammation, lower economic status may delay axSpA diagnosis

But older age at symptom onset linked to shorter delays

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by Patricia Inacio PhD |

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Uveitis, a form of eye inflammation, and lower socioeconomic status are both linked to a longer time to diagnosis in people with axial spondyloarthritis, known as axSpA, a study reports.

In contrast, older age at symptom onset is associated with shorter delays, the researchers noted.

“These results suggest that enhanced screening and education strategies targeting ophthalmology clinics as well as patients and communities with increased socioeconomic vulnerability may help reduce diagnostic delay in axSpA,” the team wrote.

The study, “Factors associated with diagnostic delay in axial spondyloarthritis: impact of clinical factors and social vulnerability,” was published in the journal Arthritis Care & Research.

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axSpA diagnosis often takes up to 8 years after symptoms start

axSpA is a type of chronic arthritis that mainly affects joints in the spine, pelvis, and chest. It’s known as ankylosing spondylitis (AS) when these changes can be seen on an X-ray, and as nonradiographic axSpA when no such damage is detected with this approach.

People with axSpA often wait up to eight years after symptom onset for a diagnosis. The fact that back pain, a typical axSpA symptom, is more commonly caused by other issues is thought to be one of the reasons for this delay.

While “longer diagnostic delay has been associated with disability and unemployment,” the researchers wrote, it’s unclear whether other factors also play a role.

The scientists reasoned that complications affecting other body parts — namely uveitis and peripheral arthritis, which usually affects the large joints of the arms and legs — could shorten the time to diagnosis. Conversely, a lower socioeconomic status would be linked with longer delays.

To test these theories, the team led by researchers at the Brigham and Women’s Hospital, in Boston, analyzed electronic health data from patients diagnosed with axSpA or AS. The patients were followed between December 1990 and October 2021, with their data recorded for a median of 11.5 years.

The researchers assessed the length of diagnostic delay, which was determined from the first time patients reported back pain symptoms, as well as disease manifestations and specialty care prior to diagnosis. Patients’ social vulnerability index, known as SVI, also was determined. This is a composite measure of poverty, lack of access to transportation, crowded housing, and household income.

The final analysis involved 554 axSpA patients, with men comprising nearly two-thirds of the group. About 77% were white, and the median age at symptom onset was 29.5. Three-quarters of the participants had private insurance, and 67% fulfilled the criteria for AS at the time of diagnosis.

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Nearly 2 times greater risk of delayed axSpA diagnosis for those with AS

The participants’ axSpA diagnoses were delayed by a mean of 6.8 years, the researchers found. A total of 128 patients were diagnosed within a year of symptom onset, with this short delay group accounting for about 23% of all participants. More than 30% — 169 patients — were diagnosed one to four years after symptom onset, making up the medium delay group. The remaining 257 participants, or about 46% of the total, experienced a long delay, of more than four years.

Compared with the short and medium delay groups, those with the longest diagnostic delay had a higher prevalence of AS at diagnosis (76% vs. 58% and 62%).

Moreover, 26% of the long delay group had uveitis prior to diagnosis, while 12% of the short delay group and 11% of the medium delay group experienced this symptom. Those with a long diagnostic delay also sought ophthalmology care more often than the other participants.

Among those with uveitis prior to their axSpA diagnosis, 18% were referred by an ophthalmologist to a rheumatologist. These patients were diagnosed a median of 2.6 years following uveitis onset.

Using a statistical analysis, the researchers found that older age at symptom onset was associated with shorter diagnostic delays, after adjusting for the participants’ sex and self-reported race. Peripheral arthritis at or prior to diagnosis was associated with lower risks of being in the longer delay groups.

In contrast, uveitis before an axSpA diagnosis was linked to a 2.8 times higher risk for diagnostic delays, while AS at diagnosis increased such risk by 1.9 times.

These findings may help identify education and screening strategies to facilitate timely axSpA diagnosis.

Also, a higher social vulnerability — specifically defined as an SVI at or above the 80th percentile nationally — meant a 91% greater risk of delayed diagnosis, after adjusting for age, sex, and race.

The link between SVI and longer delay was maintained after adjusting for clinical factors, such as having AS at diagnosis or having peripheral arthritis or uveitis at or prior to diagnosis. After adjusting for AS, peripheral arthritis, and uveitis, the risk increased by about twofold.

Finally, a different analysis was conducted in 316 patients who had received primary care at the Mass General Brigham system prior to being diagnosed with axSpA.

Again, the results showed that a history of uveitis and AS prior to diagnosis was associated with a longer diagnostic delay, whereas older age at symptom onset correlated with a shorter delay.

Overall, “we identified several clinical and socioeconomic factors that may influence diagnostic delay in axSpA,” the researchers wrote.

“These findings may help identify education and screening strategies to facilitate timely axSpA diagnosis,” they concluded.