A blinded clinical study using a subepidermal moisture biocapacitance measurement device for early detection of pressure injuries

Abstract

This study aimed to evaluate the sensitivity and specificity of subepidermal moisture (SEM), a biomarker employed for early detection of pressure injuries (PI), compared to the "Gold Standard" of clinical skin and tissue assessment (STA), and to characterize the timing of SEM changes relative to the diagnosis of a PI. This blinded, longitudinal, prospective clinical study enrolled 189 patients (n = 182 in intent-totreat [ITT]) at acute and post-acute sites (9 USA, 3 UK). Data were collected from patients' heels and sacrums using a biocapacitance measurement device beginning at admission and continuing for a minimum of 6 days to: (a) the patient developing a PI,from care, or (c) a maximum of 21 days. Standard of care clinical interventions prevailed, uninterrupted. Principal investigators oversaw the study at each site. Blinded Generalists gathered SEM data, and blinded Specialists diagnosed the presence or absence of PIs. Of the ITT population, 26.4% developed a PI during the study; 66.7% classified as Stage 1 injuries, 23% deep tissue injuries, the remaining being Stage 2 or Unstageable. Sensitivity was 87.5% (95% CI: 74.8%-95.3%) and specificity was 32.9% (95% CI: 28.3%-37.8%). Area under the receiver operating characteristic curve (AUC) was 0.6713 (95% CI 0.5969-0.7457, P < .001). SEM changes were observed 4.7 (± 2.4 days) earlier than diagnosis of a PI via STA alone. Latency between the SEM biomarker and later onset of a PI, in combination with standard of care interventions administered to at-risk patients, may have confounded specificity. Aggregate SEM sensitivity and specificity and 67.13% AUC exceeded that of clinical judgment alone. While acknowledging specificity limitations, these data Funding information Bruin Biometrics, LLC suggest that SEM biocapacitance measures can complement STAs, facilitate earlier identification of the risk of specific anatomies developing PIs, and inform earlier anatomy-specific intervention decisions than STAs alone. Future work should include cost-consequence analyses of SEM informed interventions.

Evaluating the sensitivity, specificity and clinical utility of algorithms of spatial variation in sub-epidermal moisture (SEM) for the diagnosis of deep and early-stage pressure-induced tissue damage

“…The difference between the highest and lowest readings, the delta (Δ), is used to assess tissue health; a delta <0.6 indicates low SEM variance (healthy tissue), whereas delta ≥0.6 is a high variance and indicates developing pressure damage. 14,17,18 This study describes the derivation of the SEM delta calculation in detail.…”

The cost-effectiveness of sub-epidermal moisture scanning to assess pressure injury risk in U.S. health systems

“…Model parameters on pressure injury outcomes related to SEM technology were extracted from published data about subepidermal moisture biocapacitance measurement device efficacy studied in a blinded clinical trial, a validated instrument to detect tissue damage on the sacrum and heels ("The SEM Scanner", BBI LLC, Los Angeles, CA). 6,15 Our model was adapted to analyze patients in acute care hospitals (ACH) and inpatient rehabilitation facilities (IRF), as well as residents of skilled nursing facilities (SNF). These models adjusted for variations in HAPI treatment duration and patterns, as well as general patient characteristics.…”

“…clinically meaningful differences between the highest and lowest absolute SEM values at a scanned anatomy, which indicates that the anatomy is at risk of developing a PI and that pressure injury risk mitigation should be provided to prevent further advancement to any stage of prevention injuries). 6 Pressure injury stages 2, 3, 4, and unstageable were each modeled as "tunneling states". That is, patients remained in these stages continuously for a set number of cycles (days) based on common treatment durations before they transitioned to other states.…”

“…The latter is determined by factors such as intrinsic integrity of the skin, and degree to which the skin is exposed to moisture, friction, and shear. 6 Damage from pressure injuries can develop in less than 24 h, but can take as long as five days to appear visually. 6 By the time the injury is detected, the damage to the underlying tissue is often more extensive than it appears.…”

“…6 Damage from pressure injuries can develop in less than 24 h, but can take as long as five days to appear visually. 6 By the time the injury is detected, the damage to the underlying tissue is often more extensive than it appears. 6 Thus, the success of the risk mitigation strategies for pressure injuries greatly depends upon the timely detection of progressive tissue damage in patients' anatomies.…”