Previously, it has been shown that the SSWL dynamics over time resemble an asymptotic distribution, with a high value immediately after panty removal that gradually declines over time (16). Of the 58 participants enrolled in the study, 54 (93%) expressed a declining SSWL slope (Fig. 1). Their initial mean SSWL value of 46.2 g m_2/hr + 2.6 (SE) declined gradually and significantly to 24.7 g m"2/hr + 1.6 (SE) at 30 minutes (p < 0.001). Thirty of the 54 participants enrolled in the study used some form of contraceptive medication. This subgroup displayed the same overall SSWL pattern and was not significantly different from the remaining participants not using contraceptive medication [area under the curve (AUC), p = 0.25].
Time after Panty Removal (min)
Figure 1 Comparison of vulvar and thigh skin surface water loss. Abbreviation: SSWL, skin surface water loss.
Despite being considered a semioccluded region (by virtue of garment and skin-on-skin interactions), the mean values for the inner thigh were generally constant (6 to 7 g m"2/hr) and significantly less than vulvar SSWL (Fig. 1). These data were more consistent with previously published data for the back, another semioccluded region of the body (5,7). Factors such as garment fit and mechanical abrasion, presence of an insular hair cushion, proximity to the vaginal orifice, abundance of sweat and eccrine glands, and stratum corneum thickness likely contribute to these differences (5,14,15).
The enrolled participant population had a mean age of 26.9 + 6.4 years standard deviation (SD), a mean BMI of 23.5 kg m"2 + 4.1 (SD), and a mean atopic score of 3.5 + 3.4 (SD). Within the observed range of age and BMI, both age and BMI had minimal effect on SSWL, with age having the least impact. Thus, among age, BMI, and atopic score, there was a trend for atopic score to have an impact on SSWL.
There have been numerous studies showing an increase in TEWL with noneczematous atopy (18). The limited spread of values for atopy, which may have reduced the statistical power of the model calculations, combined with the novel structural and anatomic disposition of vulvar skin, may have limited our ability to detect a stronger atopic effect on vulvar SSWL. Additional analysis of a larger population of atopic individuals is warranted.
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