A Multicenter Study of the Validity and Reliability of Responses to Hand Cold Challenge as Measured by Laser Speckle Contrast Imaging and Thermography

Abstract

ObjectiveReliable and objective outcome measures to facilitate clinical trials of novel treatments for systemic sclerosis (SSc)–related Raynaud's phenomenon (RP) are badly needed. Laser speckle contrast imaging (LSCI) and thermography are noninvasive measures of perfusion that have shown excellent potential. This multicenter study was undertaken to determine the reliability and validity of a hand cold challenge protocol using LSCI, standard thermography, and low‐cost cell phone/mobile phone thermography (henceforth referred to as mobile thermography) in patients with SSc‐related RP.MethodsPatients with RP secondary to SSc were recruited from 6 UK tertiary care centers. The patients underwent cold challenge on 2 consecutive days. Changes in cutaneous blood flow/skin temperature at each visit were imaged simultaneously using LSCI, standard thermography, and mobile thermography. Measurements included area under the curve (AUC) for reperfusion/rewarming and maximum blood flow rate/skin temperature after rewarming (MAX). Test–retest reliability was assessed using intraclass correlation coefficients (ICCs). Estimated latent correlations (estimated from multilevel models, taking values between −1 and 1; denoted as rho values) were used to assess the convergent validity of LSCI and thermography.ResultsIn total, 159 patients (77% with limited cutaneous SSc) were recruited (84% female, median age 63.3 years). LSCI and standard thermography both had substantial reliability, with ICCs for the reperfusion/rewarming AUC of 0.67 (95% confidence interval [95% CI] 0.54, 0.76) and 0.68 (95% CI 0.58, 0.80), respectively, and ICCs for the MAX of 0.64 (95% CI 0.52, 0.75) and 0.72 (95% CI 0.64, 0.81), respectively. Very high latent correlations were present for the AUCs of LSCI and thermography (ρ = 0.94; 95% CI 0.87, 1.00) and for the AUCs of standard and mobile thermography (ρ = 0.98; 95% CI 0.94, 1.00).ConclusionThis is the first multicenter study to examine the reliability and validity of cold challenge using LSCI and thermography in patients with SSc‐related RP. LSCI and thermography both demonstrated good potential as outcome measures. LSCI, standard thermography, and mobile thermography had very high convergent validity.

Raynaud phenomenon and digital ulcers in systemic sclerosis

“…66 Recent evidence suggests that laser speckle contrast imaging is a highly reliable method to assess peripheral blood perfusion in patients with SSc and healthy controls. 66,67 Laser speckle flowmetry measures perfusion at a single point and requires further research including to examine the discriminatory capacity (e.g. between primary and secondary RP) of the technique.…”

“…However, the availability of relatively low-cost mobile phone-based thermographic imaging devices may facilitate wider access to infrared thermography used under ambient conditions. 67 In addition, there are significant differences in thermography imaging protocols between centres and internationally agreed protocols/consensus would help facilitate larger multi-centre studies of SSc-vasculopathy and potential future incorporation into routine clinical practice.…”

Recent advances in the workup and management of Raynaud’s phenomenon

“…43 As baseline images were more helpful, a mobile phone thermography seems to be a feasible additional tool in the assessment of patients with RP. 44 The first multicenter study that was undertaken to determine the reliability and validity of a hand cold challenge protocol using mobile phone thermography in patients with SScrelated RP confirmed that small variations in room temperature are acceptable during the imaging. 44 Further research is needed to establish ranges of normality and abnormality and to validate the use of this method.…”

“…44 The first multicenter study that was undertaken to determine the reliability and validity of a hand cold challenge protocol using mobile phone thermography in patients with SScrelated RP confirmed that small variations in room temperature are acceptable during the imaging. 44 Further research is needed to establish ranges of normality and abnormality and to validate the use of this method. 44 Laser Doppler and other techniques Laser Doppler techniques are tools for microcirculatory research evaluating peripheral blood flow.…”

“…44 Further research is needed to establish ranges of normality and abnormality and to validate the use of this method. 44 Laser Doppler and other techniques Laser Doppler techniques are tools for microcirculatory research evaluating peripheral blood flow. They were used to monitor vasoactive therapy effects in trials on SSc.…”