[Limitations of cold tests in Raynaud's disease]

Vascular reactivity is an hemodynamic parameter, hard to quantify because its reproducibility is usually unpredictable. Cold is the most common stress used to trigger vasoconstriction in human clinical practice. Cold tests are urgently needed to fulfill the following purposes: A physiological tool to investigate cold reactivity in vascular diseases and secondly an objective means of judging and comparing the action of drugs thought to be effective in treating Raynaud's phenomenon. At present, cold tests exhibit poor reliability: The large number of tests proposed reflects the lack of agreement in this respect. Sensitivity, specificity and reproducibility fluctuate from one lab to another. It seems illusory to compare the diagnostic value of any cold test with that of clinical examination, for mathematical reasons, ie, the low prevalence of Raynaud's phenomenon in the general population (4%). At present, most of the positive results obtained in clinical trials of drugs which are effective in Raynaud's phenomenon are not correlated with the results of the cold tests.