An advanced computer assisted digital x-ray radiogrammetry technique that measures bone thickness has the potential to be a surrogate marker of radiographic progression in psoriatic arthritis, according to a report in Arthritis Research & Therapy.
The method uses software called BoneXpert to sensitively differentiate between the different stages of disease manifestation affecting bone integrity. Digital x-ray radiogrammetry (DXR) with BoneXpert has a clinical advantage over standard techniques such as radiographs through its ability to be integrated into a picture archiving and communication system that allows direct image analysis and quantification of bone loss, according to the study authors, led by Alexander Pfeil, MD, of Jena (Germany) University Hospital – Friedrich Schiller University.
The researchers used the computer-assisted diagnosis software to measure the metacarpal index (MCI) and its cortical thickness score (MCI T-score) in the metacarpal bones of 104 psoriatic arthritis (PsA) patients who fulfilled the CASPAR criteria. All patients were treated either with nonsteroidal anti-inflammatory drugs or disease-modifying antirheumatic drugs (Arthritis Res Ther. 2016;18:248. doi: 10.1186/s13075-016-1145-4).
In the total PsA cohort, the MCI T-score showed a significantly reduced negative value of –1.289. “The reduced MCI T-score was clearly associated with a reduced bone mineral density of the metacarpal bones in PsA,” the investigators wrote.
For all scores, the researchers found a severity-dependent reduction for the BoneXpert parameters of MCI, MCI T-score, T, and Bone Health Index.
The strongest reductions were seen for MCI and T using the Proliferation Score (MCI: –28.3%; T: –31.9%) and the Destruction Score (MCI: –30.8%; T: –30.9%) of the Psoriatic Arthritis Ratingen Score.
A reduced MCI and T-score was directly associated with cortical thinning and the periarticular demineralization of the metacarpal bones, and highlighted a direct association with bone destruction and bone proliferation in PsA, the investigators said.
“The measurement of periarticular bone loss can be considered a complementary approach to verify PsA-related bony changes and a surrogate marker for PsA progression,” the researchers suggested.
The technique’s high reproducibility can also be used to optimize an appropriate individual therapeutic strategy, they added.
The study had no specific funding source, and the authors declared no conflicts of interest.