Compared with the general population, patients with rheumatoid arthritis (RA) have higher optical spectral transmission (OST), which is indicative of greater joint inflammation, according to study results published in the Journal of Rheumatology.

Researchers from an inpatient rheumatology clinic in Germany enrolled 168 consecutive patients with RA and 114 hospital coworkers who volunteered to participate (control group) to examine differences in OST between the 2 groups. The investigators measured OST in the metacarpophalangeal, proximal intraphalangeal, and wrist joints of all participants

In addition to comparing OST values between patients and control individuals, the researchers also examined associations of OST with clinical and serologic activity markers and well as joint ultrasound in patients. Several different anthropometric and epidemiologic parameters were also examined in their relationship to OST in both patients and control participants.

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In an adjusted analysis, values for OST were higher in the patients with RA vs control individuals (1.89; 95% CI, 0.709-3.070; P =.002). In patients with RA, there were significant associations between OST and Disease Activity Score in 28 joints (ρ=0.313; P <.001), swollen joint count (ρ=0.361; P <.001), and C-reactive protein level (ρ=0.389; P <.001). Additional associations were found for age (ρ=0.276; P <.001) and osteoarthritis (P =.022). In both groups, men had significantly higher values for OST compared with women (P <.001), and there was also an association between OST and body mass index (P <.001).

The researchers concluded “…that OST could be influenced by anthropometric and epidemiological patient characteristics” in patients with RA and emphasized the need for further confirmation studies in this population.


Triantafyllias K, Heller C, de Blasi M, Galle PR, Schwarting A. Diagnostic value of optical spectral transmission in rheumatoid arthritis: associations with clinical characteristics and comparison with joint ultrasonography. J Rheumatol. 2020;47(6):190650.