Abstract
Diagnostic testing to differentiate between primary (idiopathic) Raynaud’s phenomenon (RP) and RP secondary to systemic sclerosis-spectrum disorders includes the use of thermal imaging (thermography) before and after a hand cold challenge (15ºC for 1 minute with 15-minute recovery monitoring period). Such a protocol is currently restricted to tertiary centres, requiring specialist equipment and environmental temperature control. Our aim was to determine whether relationships exist between baseline and post-cold challenge recovery data. If so, this could simplify testing and increase the feasibility of thermography in general rheumatology clinics.
Analysis was performed on retrospective data from patients attending for assessment of RP at a tertiary centre over a two-year period. Baseline temperature data was recorded for distal finger and hand dorsum, enabling distal-dorsal difference (finger-dorsum temperature) to be calculated. Recovery data included distal finger temperatures (immediately after cold-challenge, maximum temperature reached), time taken to reach the maximum temperature, the maximum rate of recovery and the area under the recovery curve. Data were averaged (4 fingers) for each hand. Baseline data were correlated with recovery data by Spearman rank analysis.
Data from 700 patients were analysed (median [interquartile] age, 50 [37-60] years, 518 [74%] female). Strong correlations (Table), in both left and right hands were found between baseline finger temperature and (1) temperature immediately post challenge (ρ = 0.885-0.894, p < 0.01), (2) maximum temperature reached in 15 minutes of recovery (ρ = 0.855-0.856, p < 0.01), and (3) area under the recovery curve (ρ = 0.893-0.896, p < 0.01). Correlation between baseline temperature and rates of recovery at 2 and 15 mins were moderate (ρ = 0.472-0.624, p < 0.01). Inverse relationships were identified between baseline temperature and times taken to reach maximum temperature and maximum rate of recovery, indicating that those with lower baseline finger temperature take longer to reach their maximum recovery. Results for distal-dorsal difference were similar (Table 1)
The strong correlations observed between baseline and recovery data suggest it may be possible to predict cold challenge outcomes from baseline imaging; offering an opportunity for non-specialist centres to assess RP using only ‘baseline’ thermography testing.
T.J. Gibberd: None. J. Manning: None. M. Mandzuk: None. M. Samaranayaka: None. J. Wilkinson: None. M. Hughes: None. A. Herrick: None. G. Dinsdale: None. A. Murray: None.
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