Assessing the reliability of the Modified Wash Test

The aim of this paper was to find a simple method to evaluate reliably diagnosis and severity of androgenetic alopecia (AGA) and telogen effluvium (TE).

We adopted the modified wash test (MWT), which accomplishes such task through assessing the number of shed hair and the vellus percentage. To evaluate its reliability, 25 subjects were submitted to MWT once a week for 4 consecutive weeks according to the procedure published elsewhere. The data were analysed by the intraclass correlation coefficient and ROC curves.

The subjects were diagnosed as having TE (7 subjects), AGA (6 subjects), AGA+TE (4 subjects) and normal subjects (8 patients). An almost perfect reliability was found in AGA group for both total hair and vellus hair percentage, and in normal and TE groups for vellus hair count. Good reliability were found in all other cases, but in the total hair count in normal subjects in which it was only moderate. The areas under the ROC curve showed a sensitivity and specificity ranging from 50% to 100%.

MWT can be employed with confidence in the office. It is simple, non-invasive and non-expensive and helps to distinguish TE from AGA, to identify cases of association TE+AGA, to assess the severity of the three conditions and, in TE+AGA association, to select which one is the most important and should be treated first. Possible biases and drawbacks are discussed.