# Concurrent validity and agreement of the HerniaCare Lab device for abdominal wall strength assessment

## TL;DR

The HerniaCare Lab device shows strong agreement with a standard tool for measuring abdominal strength in hernia patients, offering a portable and low-cost alternative.

## Contribution

The study validates the HerniaCare Lab as a reliable, low-cost device for assessing abdominal wall strength in hernia patients.

## Key findings

- HerniaCare Lab showed a mean strength overestimation of +22.3 N compared to the Activforce 2.
- The devices demonstrated a very strong correlation (ρ = 0.95) and good concordance (CCC = 0.89).
- Bland–Altman analysis revealed a mean bias of +24.9 N with wide 95% limits of agreement.

## Abstract

Currently, no standardized, low-cost, and portable method is available for assessing abdominal wall strength in patients with incisional hernias, addressing the limitations of traditional dynamometry.

This cross-sectional validation study compared the HerniaCare Lab device performance with the Activforce 2 hand-held dynamometer in92 adults diagnosed with abdominal wall hernias. Isometric trunk flexion strength was measured under identical conditions, and agreement between devices was analyzed using non-parametric tests, correlation, and concordance statistics.

The HerniaCare Lab showed systematically higher strength values than the Activforce 2 (mean difference = + 22.3 N, p < 0.001) but demonstrated a very strong positive correlation (ρ = 0.95, p < 0.001) and good concordance (CCC = 0.89). Bland–Altman analysis revealed a mean bias of + 24.9 N with 95% limits of agreement from − 17.7 to+ 67.5 N, and a slight proportional bias at higher force levels.

Despite predictable overestimation, the HerniaCare Lab exhibits strong concurrent validity and good agreement with an established reference device, supporting its potential clinical utility for objective, reproducible, and accessible assessment of abdominal wall strength in surgical populations.