A standardized finger cooling test for Raynaud's phenomenon: diagnostic value and sex differences

In 99 patients with primary Raynaud's phenomenon (RP), in 97 with secondary RP and in 101 healthy subjects, finger skin temperature and laser Doppler flux were measured before, during and after immersion of the hand in a 16°C water bath. We determined the baseline value, the values at the end of the cooling period and after 12 and 20 min of recovery, the percentual decrease during cooling and the mean values during cooling, during recovery and during the whole test. Most of the finger skin temperature and laser Doppler flux parameters were significantly lower in females than in males in all three groups. There were no significant differences between patients with either primary or secondary RP. In both sexes, all test parameters (with the exception of the percentual decrease during cooling) were significantly lower in the patients with RP than in healthy subjects. With a diagnostic specificity of 70%, the sensitivity varied between 55% and 81 %for the different test parameters. Although, in both sexes, finger skin temperature and laser Doppler flux values before, during and after cooling were significantly lower in patients with RP than in healthy subjects, the considerable overlap between both groups limits the diagnostic value in individual cases.