Prognostic performance of the maximal systolic acceleration at the hallux in healing of foot ulcers: a retrospective cohort study

Abstract

The accurate prediction of foot ulcer healing remains a major challenge in clinical practice. To date, no reliable bedside tests are available. The primary aim of this study was to determine the prognostic performance of the maximal systolic acceleration (ACCmax) to predict ulcer healing. Secondary objectives comprised the investigation of the prognostic accuracy in patients prone to medial arterial calcification, and to assess the potential risk of amputation. A single-centre retrospective cohort study was conducted. Patients ≥ 18 years-old who presented with a new-onset ulcer (i.e. Fontaine IV and neuropathic ulcers) on the foot and underwent an ACCmax measurement at the hallux were included. Ulcer healing was defined as an intact skin with epithelialization after three or 12 months of follow-up. Prognostic performance was calculated by using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR) and negative likelihood ratio (NLR). In total, 136 patients with 143 wounds were included. Almost half of the patients were diagnosed with diabetes mellitus (47%) and wound infection was present in 42% of cases. After three months of follow-up, a NPV of 97.9%, PLR of 3.25 and NLR of 0.19 was found when applying an ACCmax threshold of 0.5 m/s2. When looking at 12 months, these numbers were 85.6%, 2.72 and 0.50, respectively. Subgroup analysis for patients with diabetes mellitus and chronic kidney disease showed comparable results. The risk of amputation increased significantly when a measurement below 1.0 m/s2 was present (odd ratio 5.3, p = 0.010). ACCmax measurements at the hallux can have additional prognostic value in patients with foot ulcers. An ACCmax below 1.0 m/s2 is associated with non-healing of an ulcer and a higher risk of amputation, while higher ACCmax values are associated with limb salvage. Therefore, ACCmax could be used for grading ischemia in a wound classification system.