Objectives: To perform a systematic review evaluating the use of infrared thermography (IRT) as an endpoint in clinical trials of Raynaud's phenomenon (RP).
Methods: Articles reporting the use of IRT and Raynaud's phenomenon were identified following systematic searches of PubMed, EMBase, MEDLINE and AMED databases. Articles incorporating IRT as an endpoint in a therapeutic trial were selected for full text analysis. Data extracted from articles included study design, study size, intervention, clinical and thermographic endpoints, and outcomes. Studies were scored on their methodological quality. Data analysis involved a descriptive analysis of the studies, along with a secondary analysis focusing on agreement between clinical and thermographic outcomes in the larger, better-described studies.
Results: Thirty-two studies evaluating 654 patients with RP were assessed. Significant heterogeneity between studies precluded any attempt at formal meta-analysis. Most studies were small (median 15.5 patients) and open-label design (19/32, 59.4%). The majority of studies (18/32, 56.3%) reported improvements in both clinical and thermographic endpoints. Thermographic parameters showing agreement with clinical endpoints in therapeutic trials included baseline hand/finger absolute temperature and parameters derived following local cold challenge, including longitudinal thermal gradients and percent re-warming.
Conclusions: No single thermographic parameter has emerged as the preferred endpoint for clinical trials of RP. Objective microvascular imaging tools such as IRT have the potential to overcome the limitations of self-report assessment of RP. Future studies should continue to evaluate IRT, alongside recommended self-reports, in an attempt to validate objective microvascular assessment tools in therapeutic trials of RP.