Validation of a novel smartphone application‐enabled, patient‐operated skin barrier device

Abstract

Background Transepidermal water loss (TEWL) and surface capacitance measure skin barrier permeability and stratum corneum (SC) hydration, respectively, and are frequently utilized in atopic dermatitis clinical trials. Many barrier devices are costly and often used only in the academic setting. GPSkin is a low‐cost, patient‐operated device that measures both TEWL and SC hydration. This study aimed to test the reliability of GPSkin and assess its correlation with current industry standards. Materials and Methods GPSkin was compared to the Biox AquaFlux (TEWL) and Courage‐Khazaka Corneometer (SC hydration). Participants with healthy skin (n = 50) collected measurements with GPSkin in Trial 1 without any device education and in Trial 2 with additional instruction. In Trial 2, the investigator also performed measurements with GPSkin. Spearman's coefficients (rs) were performed to assess device correlation. Intraclass correlation coefficients (ICC) were calculated to determine reliability. Results Overall, GPSkin was moderately correlated with current industry device measurements for TEWL (Trial 1 rs:0.48; Trial 2 rs:0.40 participant, 0.34 investigator) and SC hydration (Trial 1 rs:0.63; Trial 2 rs:0.45). GPSkin demonstrated “good” test‐retest reliability for both TEWL (ICC: 0.89) and SC hydration (ICC: 0.85) measurements when participants were provided with some device education. There was no difference in reliability between participants provided with device education and investigators. Conclusion Based on these findings, we concluded that GPSkin provides reasonably precise and reliable measurements of SC hydration and TEWL as compared to current devices.

Can a handheld device accurately measure barrier function in ichthyoses?

“…These findings are consistent with the only previously published comparative reports of gpskin TEWL measurements, which compared gpskin vs AquaFlux 4 and gpskin Barrier Light ® vs Tewameter dTM300 ® , 7 both in healthy adult skin. Our Bland‐Altman data suggest that the agreement between AquaFlux AF200 ® and gpskin Barrier Light ® readings is less at higher TEWL values, which parallels the greater differences found by Grinich et al 4 in lesional vs nonlesional atopic dermatitis skin. However, at higher vs lower values of the overall cohort, the Spearman correlation was similar between the two instruments.…”

“…Demographic information was collected, and patients (or parent if under 8 years of age) were asked to rate the severity, based separately on erythema and scaling, each with a 5‐point Likert scale (0‐4). A single trained investigator (Dr Murphrey) with assistance (Dr Paller) serially obtained TEWL readings on two successive days using the AquaFlux and gpskin devices 4 . Three serial TEWL readings were taken at non‐overlapping locations on the volar arm to allow for calculation of means and to assess test‐retest reliability for each device.…”

Synchronized in vivo measurements of skin hydration and trans‐epidermal water loss. Exploring their mutual influences

“…The data provided by the GPSkin â were found highly correlated with those provided by the two other instruments. A very recent paper [23] confirmed the correlation of data provided by the GPSkin â instrument with those obtained by the Corneometer â and the Aquaflux AF200 â instrument (Biox systems TM , London, UK). As GPSkin â can record skin hydration and TEWL on a same skin site, at a same moment, such asset precludes the problem of precise replacements of probes onto the same skin site.…”

“…The slight changes observed by both vehicle and/or bare skin, at all timings, are non-significant (P > 0.2 and above). The objective of the present work differs with the recently published study [23]. The latter mostly aimed at correlating the data provided by the GPSkin barrier â with those provided by two other instruments (CM 825 Corneometer â , Aquaflux AF200 â ), under two conditions (self-used or operator driven).…”

“…As initially presented , this system integrates two electronic sensors (see Photo ). The circular part of the instrument, in close contact with the skin, comprises two electrodes that measures the skin impedance (its dielectric constant), similar to that of the Corneometer ® , (Courage and Khazaka™, Köln, Germany) with a different frequency (1 kHz).…”