Testing Elevated Protease Activity: Prospective Analysis of 160 Wounds

OBJECTIVE: Given that local elevated protease activity (EPA) has been implicated in impaired wound healing, a prospective single-center study was conducted to assess protease activity in various wound types. METHODS: Protease activity was determined using an easy-to-use test system (Woundchek Protease Status Test Kit; Systagenix, Gatwick, United Kingdom) in 160 wounds in 143 patients. The assay detects the combined activity of inflammatory proteases, mainly matrix metalloproteinases 8 and 9 and human neutrophil elastase. RESULTS: Local EPA was detected in 29 of 153 validly tested wounds (18.95%). No difference was detected between acute and chronic wounds, regardless of associated or causative conditions, with the sole exception of surgical wounds. Surgical wounds showed EPA significantly less frequently than nonsurgical wounds. Among nonsurgical wounds, EPA was detected more frequently in acute compared with chronic wounds. Wounds with signs of unimpeded healing (granulation or epithelialization) showed EPA less often than wounds covered with necrotic tissue or a fibrin layer. However, 14% of wounds with epithelialization or granulation exhibited EPA potentially impeding wound healing. Wounds treated with moisture-retentive wound dressings showed EPA significantly less frequently compared with wounds bandaged with dressings with less moisture-retentive properties. Remarkably, none of the wounds treated with collagen/oxidized regenerated cellulose/silver, which is a protease-modulating dressing, showed EPA. CONCLUSIONS: To the study authors' knowledge, this is the largest study assessing EPA in various wound types. The convenient applicability of the test system provides a basis for future studies assessing the pathophysiologic relevance of EPA. In some unsuspicious wounds, early detection of EPA might precede impaired healing and prompt protease-modulating treatment before failure to heal becomes apparent.