Evaluation of Cohen's Cross-Section Trichometer for Measuring Hair Quantity

BACKGROUND Until now, there has been no reliable, simple method available for measuring hair quantity that is suitable in clinical practice. Recently, the cross-section trichometer by Cohen has been introduced. This study was designed to test its clinical utility. METHODS The hair mass index (HMI) is ratio of the cross-sectional area of an isolated bundle of hair and the premeasured area of skin from which it was taken using the trichometer device. The intra-and interobserver reproducibility of measurements at the same location and after relocation were evaluated. RESULTS For intraobserver reproducibility, the HMI ranged from 3 to 120 (mean difference .2, 95% confidence interval [CI] = -4.7-5.1, correlation coefficient [r] = .99. For interobserver reproducibility, the HMI ranged from 18 to 119 (mean difference -. 4, 95% CI = -8,0-7,2, r = .98). With relocation, the HMI ranged from 2 to 113 (mean difference -1.0, 95% CI = -10.1-8.1, r = .97). Measurements took 5-10 minutes per area. CONCLUSION Measurements were simple to perform, and the data showed high reproducibility. The trichometer is a promising technology for hair quantity measurements and has multiple clinical and research applications.