P144 Extended examination of post-challenge rewarming in patients with systemic sclerosis, as assessed by thermography

Abstract Background/Aims Clinical trials of systemic sclerosis (SSc)-related Raynaud’s phenomenon require better objective outcome measures. Thermography-monitored cold-challenge is a validated imaging technique. Cold-challenge is monitored for 15-minutes during rewarming, however, patients often do not fully rewarm. Knowing rewarming time enables better planning of daily trial protocols (e.g. challenges before and after treatment). The aim of this study was to test the hypotheses that 15-minute rewarming measurements are predictive of two-hour rewarming and that patients rewarm within a two-hour period. Methods Baseline thermography of the hands and cold-challenge was performed (1 minute, 15oC water, gloved hands submerged). Post-cold challenge, images were taken every 15s (to 15 minutes), every 5 minutes (to 30 minutes), every 10 minutes (to 60 minutes) and every 15 minutes (to 120 minutes). Baseline finger temperature (average, eight fingers, Tbase) and distal dorsal difference (DDD, temperature difference between dorsum ofthe hand and distal finger) were calculated from baseline images. Mean finger temperature difference (post-cold challenge-baseline, Tdiff), time to 25% (t25%), 50% (t50%), 100% (t100%) rewarming, maximum temperature achieved (Tmax), time to Tmax (tmax), area under the rewarming curve (AUC), and final temperature (Tf) were calculated. Cox regression assessed associations between Tbase, Tmax, Tf, DDD and AUC. Results Twenty patients with SSc were recruited; median (interquartile range) age 62 (53-69), duration of RP 16 (7-26) years. Fourteen patients (70%) rewarmed within two hours. Data, Table 1. Cox regression showed positive relationship between AUC and t25%, t50% and t100% and a negative relationship between Tbase, t50% and t100%. In the non-rewarming subset, 3/6 and 1/6 achieved t25%, t50% in 15 minutes. 13/14 patients that rewarmed achieved t25% and 11/14 achieved t50% within 15 minutes. Results suggest that the likelihood of longer-term rewarming is predicted the initial 15-minute rewarming. Conclusion Tbase was reached by the majority of patients with SSc in a two-hour window, therefore, a second or third cold challenge could be incorporated into early Phase II study protocols within a study day. Patients reaching t50% within 15 minutes were highly likely to rewarm fully over two hours; thus 15-minute rewarming may aid screening to identify patients who will fully rewarm. Disclosure A. Ndosi: None. G. Dinsdale: None. J. Manning: None. M. Mandzuk: None. S. Wilkinson: None. A. Herrick: None. A. Murray: None.