medwireNews: A panel of four soluble biomarkers comprising markers of cartilage metabolism, metabolic syndrome, and inflammation could distinguish psoriatic arthritis (PsA) from osteoarthritis (OA), researchers report.
“These two conditions can be confused since they both affect distal joints, although OA is generally not an inflammatory condition,” lead author Dafna Gladman (University of Toronto, Ontario, Canada) told medwireNews.
“Occasionally patients with OA also present with what looks like erosive arthritis,” she added.
In their discovery analysis, Gladman and co-researchers compared levels of 15 serum markers in 77 individuals with PsA, 201 OA patients undergoing surgery, and 76 healthy controls using samples from a Toronto biobank.
Median serum levels of cartilage oligomeric matrix protein (COMP) were significantly higher in patients with PsA than those with OA (193.8 vs 148.2 ng/mL), as were levels of the metabolic syndrome marker resistin (37.5 vs 26.9 ng/mL) and the inflammatory marker monocyte chemoattractant protein-1 (MCP-1; 301.7 vs 157.8 pg/mL). Conversely, levels of nerve growth factor (NGF), another marker of inflammation, were significantly lower among patients with PsA compared with the OA group (6.1 vs 8.3 pg/mL).
Median levels of these markers were also significantly different among healthy controls compared with PsA or OA patients, with controls having intermediate COMP and MCP-1, higher resistin, and lower NGF levels relative to the PsA and OA groups.
In a multivariate logistic regression analysis, levels of the four markers were significantly different in patients with PsA and those with OA after adjustment for age and sex.
The panel of biomarkers “distinguished PsA from OA with very high sensitivity and specificity, and its addition to a model including age and sex only improved the area under the curve significantly,” said Gladman.
Indeed, area under the receiver operating characteristic curve analysis demonstrated that a model combining the four biomarkers with age and sex correctly distinguished between people with PsA and those with OA on 99.8% of occasions. By comparison, a model including age and sex alone had a significantly lower predictive ability, at 87.3%.
The team then validated their model in samples from a further 73 PsA and 75 OA patients included in the same biobank as the discovery set, finding similar results to those obtained in their initial analysis.
“Although we already validated these results in an additional group of patients locally, [the panel] still [needs] to be validated in a prospective study before it can be put into clinic setting,” noted Gladman.
The researchers write in the Annals of the Rheumatic Diseases that OA patients included in the study were limited to “those undergoing joint replacement surgeries and may not be representative of the general population of patients with OA,” and therefore “it is necessary to replicate these results using patients with OA seen in family practice or rheumatology clinics.”
And they conclude: “After further verification and validation, these markers could provide a valuable tool for the improved diagnosis and management of both OA and PsA thus resulting in improved patient outcomes.”
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