medwireNews: Measuring erythrocyte sedimentation rate (ESR), angiopoietin-2/-1 ratio, and matrix metalloprotease (MMP)-3 levels may help discriminate patients with isolated polymyalgia rheumatica (PMR) from those with concomitant giant cell arteritis (GCA), research suggests.
The study, by Yannick van Sleen (University Medical Center Groningen, the Netherlands) and colleagues, also found that platelet counts could be used to distinguish patients with GCA from those with look-alike conditions and infections.
“Screening for these markers could aid the decision to start further diagnostic workup including imaging,” they say.
The research involved 262 treatment-naïve participants, including 52 with GCA and 25 with isolated PMR from the Aarhus AGP cohort plus 48 with GCA and 39 with isolated PMR from the Groningen GPS cohort. In addition, there were 64 healthy controls, 18 individuals with GCA look-alike conditions (infections, atherosclerosis, chronic kidney disease, central vein occlusion, or polyarthritis), and 16 controls with infection.
Overall, the investigators found that levels of C-reactive protein (CRP), angiopoietin-2, YKL-40, calprotectin, soluble CD206, proteinase 3 (PR3), and alpha-1 anti-trypsin, along with ESR and platelet and leukocyte counts, were significantly higher in all patient groups relative to healthy controls.
In addition, MMP-3 levels were significantly elevated in PMR patients versus healthy controls but were not significantly raised in participants with GCA.
Further analysis revealed that CRP, ESR, MMP-3, and soluble CD206 levels plus angiopoietin-2/-1 ratio consistently discriminated between patients with concomitant GCA and PMR and those with isolated PMR.
The strongest discriminators were ESR, angiopoietin-2/-1 ratio, and MMP-3 with areas under the receiver operating characteristic curves (AUC) ranging from 0.77 to 0.88, indicating that elevated ESR levels and angiopoietin‐2/‐1 ratios along with lower MMP‐3 levels “identify concomitant GCA in PMR patients,” van Sleen et al remark.
By comparison, the AUC for CRP was 0.63–0.68 depending on the cohort.
In addition, the researchers observed that the presence of weight loss at diagnosis was significantly more common in people with GCA plus PMR relative to those with PMR alone.
The team also compared biomarker levels in the GCA group with those in the GCA look-alike group and infection controls and found that platelet counts were elevated in the people with GCA but not in those with look-alike conditions. The AUC for discriminating between these two groups was 0.72–0.75.
Serum MMP-3 and PR3 levels were also lower, and weight loss more common, in the GCA group versus the look-alike and infection control groups.
Writing in Arthritis Research & Therapy, van Sleen and co-authors conclude that their study “provides robust evidence for more disease-specific biomarkers that may substantially improve diagnostic procedures for GCA patients.”
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