Background There is great debate regarding which patients to treat with expensive effective therapies for rheumatoid arthritis (RA).
Objectives To identify RA patients rapidly and easily who are destined to have progressive destructive disease in the next year.
Methods A digital dermal thermometer was used to record vital signs, on the skin of the forehead for a core temperature and then placed over the most painful peripheral joint (according to the patient) to record the temperature over the painful joint. This process adds less than a minute to the vital signs. Patients were sequentially entered into the program who were sero-positive and treated over the next year with methotrexate 20-25 mg/week. Corticosteroid therapy and Nsaids were allowed over the year but no other biologic or DMARD. Hand/wrist xrays were obtained initially and repeated 1 year later. A modified van der Heijde total Sharp score (mTSS) was read in December 2013 without sequence order or identifiers by a single reader (MG). The minimum meaningful change in mTSS was 5. Laboratory tests WESR and CRP were done on the day of the first xray and labs evaluated for prognostic value compared to the xray results. Medical history was reviewed for sex and years since diagnosis. A small group of subjects without RA (n=25) were used as controls to evaluate the usual range of joint temperature.
Results 208 patients were evaluated. One group had hot joints (n=104) with the joint temperature exceeding the core temperature by an average of +1.06 degrees. The other group (n=104) had joints with a lower temperature than the core temperature by an average of -4.4 degrees. The control group of normal individuals (n=25) documented a – 6.3 temperature at the wrist and -12.0 temperature at the 2nd MCP, compared to the core temperature.
There was a strong statistically significant difference in mTSS in 12 months change in mTSS between the hot joint group (8.7±6.2, CI 2.1) and the cool joint group (2.5±1.4, CI 0.5). In the hot joint group, 27 patients did not have meaningful progressive erosive destructive disease, and 77 had a change in mTSS ≥5, clear xray evidence of new damage (false positive identification for one year 26%). In the cool joint group, 97 did not have new xray damage and 7 did have bone or cartilage damage (false negative 7%). Therefore, 74% of the hot joint group had new xray damage in the next one year. If the 208 patients were combined, 40% had new xray damage in one year.
There was a lower age and more recent onset of RA disease in the hot joint group (p<0.05) and a higher WESR. However, the sed rates between the hot and cool joint groups had a large overlap and sed rate does not work well on an individual case basis to determine who will have new destructive disease. There was no difference between groups in sex (83% female in each group) nor a difference in CRP between groups.
Conclusions Joint temperature can be ascertained along with vital signs in less than a minute. This information can enrich the pool of active RA patients likely to have progressive destructive disease in the next year. This may identify patients who would most benefit from expensive effective RA therapies and add concrete data to the great debate.
Disclosure of Interest None declared