Knowing ‘fluid’ nature of axial spondyloarthritis critical to preventing serious outcomes

ORLANDO, Fla. — Understanding the nuances of spondyloarthropathy diagnostic criteria can help prevent “debilitating” consequences, according to a presenter at the 2024 Rheumatology Nurses Society annual conference.

“Chronic back pain is huge — we all deal with it,” J. Nicholas Manwaring, MSN, APRN, FNP-C, a nurse practitioner in the division of rheumatology at the Alaska Native Tribal Health Consortium, in Anchorage, and a commander in the U.S. Public Health Service Commissioned Corps at the Indian Health Service, told attendees. “We are going to see these patients come through our clinic, so it is important for us to differentiate between inflammatory and mechanical back pain.”

However, despite this prevalence, the available research has struggled to keep pace.

“The studies, unfortunately, are not really good, especially for non-radiographic axial spondyloarthritis,” said Manwaring, who is also on the RNS board of directors. “It is really underdiagnosed.”

In fact, both radiographic and non-radiographic axial SpA are under-diagnosed, according to Manwaring. Between 10% and 40% of patients with non-radiographic disease will develop radiographic manifestations, he said.

“It is important that we continue to follow up with them because these diagnoses are fluid, they are not static,” Manwaring said.

Importantly, axial SpA, peripheral spondyloarthritis, undifferentiated peripheral spondyloarthritis and non-radiographic axial SpA may all have overlapping symptomatology, he added.

Manwaring encouraged ongoing vigilance in managing all these complex patient populations, suggesting that even if axial SpA was undiagnosed or misdiagnosed previously, it does not mean that the previous clinician was wrong.

“Maybe the patient progressed,” he said.

According to Manwaring, the various manifestations of axial SpA can develop in the cervical spine or include peripheral involvement.

“A lot of times they will have enthesitis, syndesmophytosis and sacroiliitis,” he said. “There is often concurrent uveitis.”

Despite these hallmark complications, many non-rheumatology providers may not recognize the significance of these signs.

“No one has made the tie between their back pain and their eye,” Manwaring said.

Stressing the “fluid nature” of these disease states, he added that patients may have a genetic predisposition that evolves into inflammatory back pain.

“Sometimes it goes into remission, sometimes it develops into non-radiographic axial SpA,” Manwaring said.

Some patients will never develop radiographic disease, while others will “fall outside” of any criteria altogether, he added.

“It is important not to put people into a box,” Manwaring said. “There are patients who will benefit from treatment who are not in any of these easy categories.”

Regarding genetic factors, it is commonly assumed that a mutation in the HLA-B27 gene is present in all patients with spondyloarthritis, according to Manwaring. However, presence of this mutation can vary based on the patient’s background and ethnicity.

“Do not put all your money on HLA-B27, unfortunately,” Manwaring said. “Clinical diagnosis is more helpful.”

Rheumatoid factor and antinuclear antibodies will be negative, while erythrocyte sedimentation rate and C-reactive protein will be elevated in most patients, he added.

“It is likely genetic with some environmental factors, as we noted,” Manwaring said.

He additionally noted that clinicians should also be aware of the presence of enthesitis and dactylitis.

Another tip is to optimize imaging strategies.

“The best X-ray for the initial view is the AP pelvis,” Manwaring said. “Bilateral view of sacroiliac joint is also helpful.”

The goal of this deep, nuanced understanding of various axial SpA presentations and manifestations is to prevent the disease from progressing before treatment initiation.

“[Following progression,] then you get complete effusion of the spine, which is terribly debilitating for patients,” Manwaring said. “We want to prevent that.”