THU0087 UTILITY OF INFRARED THERMOGRAPHY FOR THE EVALUATION OF RHEUMATOID ARTHRITIS

Abstract

Background: Rheumatoid Arthritis (RA) is a chronic inflammatory disease, which predominantly affects the hands. Currently in clinical practice, we explore the number of swollen and painful joints in order to evaluate the activity of the disease. Infrared thermography (IT) is a non-invasive, lacking ionizing radiation, operator-independent and low-cost technique that allows to measure the temperature of the cutaneous surface through the taking of a photograph. Objectives: To determine the utility of IT in the evaluation of hands arthritis in patients with RA. Methods: A cross-sectional study was performed, including patients with RA according to 2010 ACR/EULAR criteria attended in our Hospital between February and March 2018. Demographic, clinical and analytical characteristics of patients were registered. Number of painful and swollen joints were assessed for each patient, including wrist, metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints. Subsequently, a standardised photograph of the dorsal aspect of both hands was taken with a thermal camera (FLIR T250 model) ([Figure 1][1]). With this technique mean temperature (MeanT) and maximum temperature (MaxT) were assessed at each joint. Also, differential temperature (DifT) was assessed (mean temperature at joint - temperature at forearm skin). Results: We included a total of 42 patients. 76% were women, mean age at diagnosis was 56.7 years old. 29 patients were positive for rheumatoid factor and 31 for anti-citrullinated peptide antibody. At the time of the assessment, medium CRP was 9.19 mg/L and ESR was 14.77 mm/h. MeanT for the 65 swollen joints was 1.5°C higher than the 847 non-swollen joints (p=0.000). Independent analysis for each joint level (wrist, MCP and PIP) revealed higher temperature in swollen joints ([Table 1][2]). Similar results were obtained for painful joints. ROC curves and areas under the curve (AUC) were calculated for wrist, MCP and PIP joints, obtaining the most favorable results for DifT in wrist and MCP joints, and for MaxT in PIP joints, allowing to calculate a cut-off point at each joint level ([Table2][3]). ![Figure 1][4] Figure 1 Selective temperature increase over third PIP of the left hand. View this table: Table 1 Correlation between swollen joints and MeanT, MaxT and DifT. View this table: Tabla 2. AUC, sensibility and specifity. Conclusion: In patients with RA, there is a statistically significant relationship between joint temperature measured by thermal imaging and the presence of swollen and painful joints in the assessment by the rheumatologist. The ROC curves indicate an acceptable sensitivity and specificity and allow to determine cut-off temperatures for clinical use. Infrared thermography could be a useful tool in the assessment and monitoring of arthritis in RA patients. Reference: [1] Jones B, Hassan I, Tsuyuki RT, Dos Santos MF, Russell AS, Yacyshyn E. Hot joints: myth or reality? A thermographic joint assessment of inflammatory arthritis patients. Clin Rheumatol. 2018 Sep 20;37(9):2567–71 Disclosure of Interests: None declared [1]: #F1 [2]: #T1 [3]: #T2 [4]: pending:yes